TY - BOOK
A1 - Abedjan, Ziawasch
A1 - Golab, Lukasz
A1 - Naumann, Felix
A1 - Papenbrock, Thorsten
T1 - Data Profiling
T3 - Synthesis lectures on data management, 52
Y1 - 2019
SN - 978-1-68173-446-0
PB - Morgan & Claypool Publishers
CY - San Rafael
ER -
TY - JOUR
A1 - Adnan, Hassan Sami
A1 - Matthews, Sam
A1 - Hackl, M.
A1 - Das, P. P.
A1 - Manaswini, Manisha
A1 - Gadamsetti, S.
A1 - Filali, Maroua
A1 - Owoyele, Babajide
A1 - Santuber, Joaquín
A1 - Edelman, Jonathan
T1 - Human centered AI design for clinical monitoring and data management
JF - European journal of public health : official journal of the European Health Association
N2 - In clinical settings, significant resources are spent on data collection and monitoring patients' health parameters to improve decision-making and provide better care. With increased digitization, the healthcare sector is shifting towards implementing digital technologies for data management and in administration. New technologies offer better treatment opportunities and streamline clinical workflow, but the complexity can cause ineffectiveness, frustration, and errors. To address this, we believe digital solutions alone are not sufficient. Therefore, we take a human-centred design approach for AI development, and apply systems engineering methods to identify system leverage points. We demonstrate how automation enables monitoring clinical parameters, using existing non-intrusive sensor technology, resulting in more resources toward patient care. Furthermore, we provide a framework on digitization of clinical data for integration with data management.
Y1 - 2020
U6 - https://doi.org/10.1093/eurpub/ckaa165.225
SN - 1101-1262
SN - 1464-360X
VL - 30
IS - 5
SP - V86
EP - V86
PB - Oxford Univ. Press
CY - Oxford
ER -
TY - JOUR
A1 - Adnan, Hassan Sami
A1 - Srsic, Amanda
A1 - Venticich, Pete Milos
A1 - Townend, David M.R.
T1 - Using AI for mental health analysis and prediction in school surveys
JF - European journal of public health
N2 - Background:
Childhood and adolescence are critical stages of life for mental health and well-being. Schools are a key setting for mental health promotion and illness prevention. One in five children and adolescents have a mental disorder, about half of mental disorders beginning before the age of 14. Beneficial and explainable artificial intelligence can replace current paper- based and online approaches to school mental health surveys. This can enhance data acquisition, interoperability, data driven analysis, trust and compliance. This paper presents a model for using chatbots for non-obtrusive data collection and supervised machine learning models for data analysis; and discusses ethical considerations pertaining to the use of these models.
Methods:
For data acquisition, the proposed model uses chatbots which interact with students. The conversation log acts as the source of raw data for the machine learning. Pre-processing of the data is automated by filtering for keywords and phrases.
Existing survey results, obtained through current paper-based data collection methods, are evaluated by domain experts (health professionals). These can be used to create a test dataset to validate the machine learning models. Supervised learning
can then be deployed to classify specific behaviour and mental health patterns.
Results:
We present a model that can be used to improve upon current paper-based data collection and manual data analysis methods. An open-source GitHub repository contains necessary tools and components of this model. Privacy is respected through
rigorous observance of confidentiality and data protection requirements. Critical reflection on these ethics and law aspects is included in the project.
Conclusions:
This model strengthens mental health surveillance in schools. The same tools and components could be applied to other public health data. Future extensions of this model could also incorporate unsupervised learning to find clusters and patterns
of unknown effects.
KW - ethics
KW - artificial intelligence
KW - adolescent
KW - child
KW - confidentiality
KW - health personnel
KW - mental disorders
KW - mental health
KW - personal satisfaction
KW - privacy
KW - school (environment)
KW - statutes and laws
KW - public health medicine
KW - surveillance
KW - medical
KW - prevention
KW - datasets
KW - machine learning
KW - supervised machine learning
KW - data analysis
Y1 - 2020
U6 - https://doi.org/10.1093/eurpub/ckaa165.336
SN - 1101-1262
SN - 1464-360X
VL - 30
SP - V125
EP - V125
PB - Oxford Univ. Press
CY - Oxford [u.a.]
ER -
TY - GEN
A1 - Alibabaie, Najmeh
A1 - Ghasemzadeh, Mohammad
A1 - Meinel, Christoph
T1 - A variant of genetic algorithm for non-homogeneous population
T2 - International Conference Applied Mathematics, Computational Science and Systems Engineering 2016
N2 - Selection of initial points, the number of clusters and finding proper clusters centers are still the main challenge in clustering processes. In this paper, we suggest genetic algorithm based method which searches several solution spaces simultaneously. The solution spaces are population groups consisting of elements with similar structure. Elements in a group have the same size, while elements in different groups are of different sizes. The proposed algorithm processes the population in groups of chromosomes with one gene, two genes to k genes. These genes hold corresponding information about the cluster centers. In the proposed method, the crossover and mutation operators can accept parents with different sizes; this can lead to versatility in population and information transfer among sub-populations. We implemented the proposed method and evaluated its performance against some random datasets and the Ruspini dataset as well. The experimental results show that the proposed method could effectively determine the appropriate number of clusters and recognize their centers. Overall this research implies that using heterogeneous population in the genetic algorithm can lead to better results.
Y1 - 2017
U6 - https://doi.org/10.1051/itmconf/20170902001
SN - 2271-2097
VL - 9
PB - EDP Sciences
CY - Les Ulis
ER -
TY - JOUR
A1 - AlSa'deh, Ahmad
A1 - Meinel, Christoph
T1 - Secure neighbor discovery Review, challenges, perspectives, and recommendations
JF - IEEE security & privacy : building confidence in a networked world
N2 - Secure Neighbor Discovery is designed as a countermeasure to Neighbor Discovery Protocol threats. The authors discuss Secure Neighbor Discovery implementation and deployment challenges and review proposals to optimize it.
Y1 - 2012
SN - 1540-7993
VL - 10
IS - 4
SP - 26
EP - 34
PB - Inst. of Electr. and Electronics Engineers
CY - Los Alamitos
ER -
TY - JOUR
A1 - Altenburg, Tom
A1 - Giese, Sven Hans-Joachim
A1 - Wang, Shengbo
A1 - Muth, Thilo
A1 - Renard, Bernhard Y.
T1 - Ad hoc learning of peptide fragmentation from mass spectra enables an interpretable detection of phosphorylated and cross-linked peptides
JF - Nature machine intelligence
N2 - Fragmentation of peptides leaves characteristic patterns in mass spectrometry data, which can be used to identify protein sequences, but this method is challenging for mutated or modified sequences for which limited information exist. Altenburg et al. use an ad hoc learning approach to learn relevant patterns directly from unannotated fragmentation spectra.
Mass spectrometry-based proteomics provides a holistic snapshot of the entire protein set of living cells on a molecular level. Currently, only a few deep learning approaches exist that involve peptide fragmentation spectra, which represent partial sequence information of proteins.
Commonly, these approaches lack the ability to characterize less studied or even unknown patterns in spectra because of their use of explicit domain knowledge.
Here, to elevate unrestricted learning from spectra, we introduce 'ad hoc learning of fragmentation' (AHLF), a deep learning model that is end-to-end trained on 19.2 million spectra from several phosphoproteomic datasets. AHLF is interpretable, and we show that peak-level feature importance values and pairwise interactions between peaks are in line with corresponding peptide fragments.
We demonstrate our approach by detecting post-translational modifications, specifically protein phosphorylation based on only the fragmentation spectrum without a database search. AHLF increases the area under the receiver operating characteristic curve (AUC) by an average of 9.4% on recent phosphoproteomic data compared with the current state of the art on this task.
Furthermore, use of AHLF in rescoring search results increases the number of phosphopeptide identifications by a margin of up to 15.1% at a constant false discovery rate. To show the broad applicability of AHLF, we use transfer learning to also detect cross-linked peptides, as used in protein structure analysis, with an AUC of up to 94%.
Y1 - 2022
U6 - https://doi.org/10.1038/s42256-022-00467-7
SN - 2522-5839
VL - 4
IS - 4
SP - 378
EP - 388
PB - Springer Nature Publishing
CY - London
ER -
TY - JOUR
A1 - Andree, Kerstin
A1 - Ihde, Sven
A1 - Weske, Mathias
A1 - Pufahl, Luise
T1 - An exception handling framework for case management
JF - Software and Systems Modeling
N2 - In order to achieve their business goals, organizations heavily rely on the operational excellence of their business processes. In traditional scenarios, business processes are usually well-structured, clearly specifying when and how certain tasks have to be executed. Flexible and knowledge-intensive processes are gathering momentum, where a knowledge worker drives the execution of a process case and determines the exact process path at runtime. In the case of an exception, the knowledge worker decides on an appropriate handling. While there is initial work on exception handling in well-structured business processes, exceptions in case management have not been sufficiently researched. This paper proposes an exception handling framework for stage-oriented case management languages, namely Guard Stage Milestone Model, Case Management Model and Notation, and Fragment-based Case Management. The effectiveness of the framework is evaluated with two real-world use cases showing that it covers all relevant exceptions and proposed handling strategies.
KW - Exception handling
KW - Knowledge-intensive processes
KW - Flexible processes;
KW - Case management
Y1 - 2022
U6 - https://doi.org/10.1007/s10270-022-00993-3
SN - 1619-1366
SN - 1619-1374
VL - 21
IS - 3
SP - 939
EP - 962
PB - Springer
CY - Heidelberg
ER -
TY - JOUR
A1 - Awad, Ahmed Mahmoud Hany Aly
A1 - Weidlich, Matthias
A1 - Weske, Mathias
T1 - Visually specifying compliance rules and explaining their violations for business processes
JF - Journal of visual languages and computing
N2 - A business process is a set of steps designed to be executed in a certain order to achieve a business value. Such processes are often driven by and documented using process models. Nowadays, process models are also applied to drive process execution. Thus, correctness of business process models is a must. Much of the work has been devoted to check general, domain-independent correctness criteria, such as soundness. However, business processes must also adhere to and show compliance with various regulations and constraints, the so-called compliance requirements. These are domain-dependent requirements.
In many situations, verifying compliance on a model level is of great value, since violations can be resolved in an early stage prior to execution. However, this calls for using formal verification techniques, e.g., model checking, that are too complex for business experts to apply. In this paper, we utilize a visual language. BPMN-Q to express compliance requirements visually in a way similar to that used by business experts to build process models. Still, using a pattern based approach, each BPMN-Qgraph has a formal temporal logic expression in computational tree logic (CTL). Moreover, the user is able to express constraints, i.e., compliance rules, regarding control flow and data flow aspects. In order to provide valuable feedback to a user in case of violations, we depend on temporal logic querying approaches as well as BPMN-Q to visually highlight paths in a process model whose execution causes violations.
KW - Business process modeling
KW - Compliance checking
KW - Visual modeling
KW - Anti-patterns
Y1 - 2011
U6 - https://doi.org/10.1016/j.jvlc.2010.11.002
SN - 1045-926X
VL - 22
IS - 1
SP - 30
EP - 55
PB - Elsevier
CY - London
ER -
TY - JOUR
A1 - Azodi, Amir
A1 - Cheng, Feng
A1 - Meinel, Christoph
T1 - Event Driven Network Topology Discovery and Inventory Listing Using REAMS
JF - Wireless personal communications : an international journal
N2 - Network Topology Discovery and Inventory Listing are two of the primary features of modern network monitoring systems (NMS). Current NMSs rely heavily on active scanning techniques for discovering and mapping network information. Although this approach works, it introduces some major drawbacks such as the performance impact it can exact, specially in larger network environments. As a consequence, scans are often run less frequently which can result in stale information being presented and used by the network monitoring system. Alternatively, some NMSs rely on their agents being deployed on the hosts they monitor. In this article, we present a new approach to Network Topology Discovery and Network Inventory Listing using only passive monitoring and scanning techniques. The proposed techniques rely solely on the event logs produced by the hosts and network devices present within a network. Finally, we discuss some of the advantages and disadvantages of our approach.
KW - Network topology
KW - Inventory systems
KW - Network monitoring
KW - Network graph
KW - Service detection
KW - Event processing
KW - Event normalization
Y1 - 2015
U6 - https://doi.org/10.1007/s11277-015-3061-3
SN - 0929-6212
SN - 1572-834X
VL - 94
SP - 415
EP - 430
PB - Springer
CY - New York
ER -
TY - JOUR
A1 - Bano, Dorina
A1 - Michael, Judith
A1 - Rumpe, Bernhard
A1 - Varga, Simon
A1 - Weske, Mathias
T1 - Process-aware digital twin cockpit synthesis from event logs
JF - Journal of computer languages
N2 - The engineering of digital twins and their user interaction parts with explicated processes, namely processaware digital twin cockpits (PADTCs), is challenging due to the complexity of the systems and the need for information from different disciplines within the engineering process. Therefore, it is interesting to investigate how to facilitate their engineering by using already existing data, namely event logs, and reducing the number of manual steps for their engineering. Current research lacks systematic, automated approaches to derive process-aware digital twin cockpits even though some helpful techniques already exist in the areas of process mining and software engineering. Within this paper, we present a low-code development approach that reduces the amount of hand-written code needed and uses process mining techniques to derive PADTCs. We describe what models could be derived from event log data, which generative steps are needed for the engineering of PADTCs, and how process mining could be incorporated into the resulting application. This process is evaluated using the MIMIC III dataset for the creation of a PADTC prototype for an automated hospital transportation system. This approach can be used for early prototyping of PADTCs as it needs no hand-written code in the first place, but it still allows for the iterative evolvement of the application. This empowers domain experts to create their PADTC prototypes.
KW - process-aware digital twin cockpit
KW - low-code development approaches
KW - sensor data
KW - event log
KW - process mining
KW - process-awareness
Y1 - 2022
U6 - https://doi.org/10.1016/j.cola.2022.101121
SN - 2590-1184
SN - 2665-9182
VL - 70
PB - Elsevier
CY - Amsterdam [u.a.]
ER -
TY - JOUR
A1 - Barkowsky, Matthias
A1 - Giese, Holger
T1 - Hybrid search plan generation for generalized graph pattern matching
JF - Journal of logical and algebraic methods in programming
N2 - In recent years, the increased interest in application areas such as social networks has resulted in a rising popularity of graph-based approaches for storing and processing large amounts of interconnected data. To extract useful information from the growing network structures, efficient querying techniques are required.
In this paper, we propose an approach for graph pattern matching that allows a uniform handling of arbitrary constraints over the query vertices. Our technique builds on a previously introduced matching algorithm, which takes concrete host graph information into account to dynamically adapt the employed search plan during query execution. The dynamic algorithm is combined with an existing static approach for search plan generation, resulting in a hybrid technique which we further extend by a more sophisticated handling of filtering effects caused by constraint checks. We evaluate the presented concepts empirically based on an implementation for our graph pattern matching tool, the Story Diagram Interpreter, with queries and data provided by the LDBC Social Network Benchmark. Our results suggest that the hybrid technique may improve search efficiency in several cases, and rarely reduces efficiency.
KW - graph pattern matching
KW - search plan generation
Y1 - 2020
U6 - https://doi.org/10.1016/j.jlamp.2020.100563
SN - 2352-2208
VL - 114
PB - Elsevier
CY - New York
ER -
TY - GEN
A1 - Bartz, Christian
A1 - Yang, Haojin
A1 - Bethge, Joseph
A1 - Meinel, Christoph
T1 - LoANs
BT - Weakly Supervised Object Detection with Localizer Assessor Networks
T2 - Computer Vision – ACCV 2018 Workshops
N2 - Recently, deep neural networks have achieved remarkable performance on the task of object detection and recognition. The reason for this success is mainly grounded in the availability of large scale, fully annotated datasets, but the creation of such a dataset is a complicated and costly task. In this paper, we propose a novel method for weakly supervised object detection that simplifies the process of gathering data for training an object detector. We train an ensemble of two models that work together in a student-teacher fashion. Our student (localizer) is a model that learns to localize an object, the teacher (assessor) assesses the quality of the localization and provides feedback to the student. The student uses this feedback to learn how to localize objects and is thus entirely supervised by the teacher, as we are using no labels for training the localizer. In our experiments, we show that our model is very robust to noise and reaches competitive performance compared to a state-of-the-art fully supervised approach. We also show the simplicity of creating a new dataset, based on a few videos (e.g. downloaded from YouTube) and artificially generated data.
Y1 - 2019
SN - 978-3-030-21074-8
SN - 978-3-030-21073-1
U6 - https://doi.org/10.1007/978-3-030-21074-8_29
SN - 0302-9743
SN - 1611-3349
VL - 11367
SP - 341
EP - 356
PB - Springer
CY - Cham
ER -
TY - JOUR
A1 - Baudisch, Patrick Markus
A1 - Silber, Arthur
A1 - Kommana, Yannis
A1 - Gruner, Milan
A1 - Wall, Ludwig
A1 - Reuss, Kevin
A1 - Heilman, Lukas
A1 - Kovacs, Robert
A1 - Rechlitz, Daniel
A1 - Roumen, Thijs
T1 - Kyub
BT - A 3D Editor for Modeling Sturdy Laser-Cut Objects
JF - Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems
N2 - We present an interactive editing system for laser cutting called kyub. Kyub allows users to create models efficiently in 3D, which it then unfolds into the 2D plates laser cutters expect. Unlike earlier systems, such as FlatFitFab, kyub affords construction based on closed box structures, which allows users to turn very thin material, such as 4mm plywood, into objects capable of withstanding large forces, such as chairs users can actually sit on. To afford such sturdy construction, every kyub project begins with a simple finger-joint "boxel"-a structure we found to be capable of withstanding over 500kg of load. Users then extend their model by attaching additional boxels. Boxels merge automatically, resulting in larger, yet equally strong structures. While the concept of stacking boxels allows kyub to offer the strong affordance and ease of use of a voxel-based editor, boxels are not confined to a grid and readily combine with kuyb's various geometry deformation tools. In our technical evaluation, objects built with kyub withstood hundreds of kilograms of loads. In our user study, non-engineers rated the learnability of kyub 6.1/7.
KW - Personal fabrication
KW - laser cutting
KW - interactive editing
Y1 - 2019
SN - 978-1-4503-5970-2
U6 - https://doi.org/10.1145/3290605.3300796
SP - 1
EP - 12
PB - Association for Computing Machinery
CY - New York
ER -
TY - CHAP
A1 - Bauer, Matthias
A1 - Malchow, Martin
A1 - Meinel, Christoph
T1 - Full Lecture Recording Watching Behavior, or Why Students Watch 90-Min Lectures in 5 Min
T2 - IMCL 2018: Mobile Technologies and Applications for the Internet of Things
N2 - Many universities record the lectures being held in their facilities to preserve knowledge and to make it available to their students and, at least for some universities and classes, to the broad public. The way with the least effort is to record the whole lecture, which in our case usually is 90 min long. This saves the labor and time of cutting and rearranging lectures scenes to provide short learning videos as known from Massive Open Online Courses (MOOCs), etc. Many lecturers fear that recording their lectures and providing them via an online platform might lead to less participation in the actual lecture. Also, many teachers fear that the lecture recordings are not used with the same focus and dedication as lectures in a lecture hall. In this work, we show that in our experience, full lectures have an average watching duration of just a few minutes and explain the reasons for that and why, in most cases, teachers do not have to worry about that.
KW - e-Learning
KW - Lecture video recording
KW - e-lecture
KW - Attention span
KW - Learning behavior
Y1 - 2019
SN - 978-3-030-11434-3
SN - 978-3-030-11433-6
U6 - https://doi.org/10.1007/978-3-030-11434-3_38
SN - 2194-5357
SN - 2194-5365
VL - 909
SP - 347
EP - 358
PB - Springer
CY - Cham
ER -
TY - JOUR
A1 - Bauman, Spenser
A1 - Bolz, Carl Friedrich
A1 - Hirschfeld, Robert
A1 - Kirilichev, Vasily
A1 - Pape, Tobias
A1 - Siek, Jeremy G.
A1 - Tobin-Hochstadt, Sam
T1 - Pycket: A Tracing JIT for a Functional Language
JF - ACM SIGPLAN notices
N2 - We present Pycket, a high-performance tracing JIT compiler for Racket. Pycket supports a wide variety of the sophisticated features in Racket such as contracts, continuations, classes, structures, dynamic binding, and more. On average, over a standard suite of benchmarks, Pycket outperforms existing compilers, both Racket's JIT and other highly-optimizing Scheme compilers. Further, Pycket provides much better performance for Racket proxies than existing systems, dramatically reducing the overhead of contracts and gradual typing. We validate this claim with performance evaluation on multiple existing benchmark suites.
The Pycket implementation is of independent interest as an application of the RPython meta-tracing framework (originally created for PyPy), which automatically generates tracing JIT compilers from interpreters. Prior work on meta-tracing focuses on bytecode interpreters, whereas Pycket is a high-level interpreter based on the CEK abstract machine and operates directly on abstract syntax trees. Pycket supports proper tail calls and first-class continuations. In the setting of a functional language, where recursion and higher-order functions are more prevalent than explicit loops, the most significant performance challenge for a tracing JIT is identifying which control flows constitute a loop-we discuss two strategies for identifying loops and measure their impact.
KW - Experimentation
KW - Languages
KW - Measurement
KW - Performance
KW - JIT compilers
KW - contracts
KW - tracing
KW - functional languages
KW - Racket
Y1 - 2015
U6 - https://doi.org/10.1145/2784731.2784740
SN - 0362-1340
SN - 1558-1160
VL - 50
IS - 9
SP - 22
EP - 34
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Bilò, Davide
A1 - Lenzner, Pascal
T1 - On the tree conjecture for the network creation game
JF - Theory of computing systems
N2 - Selfish Network Creation focuses on modeling real world networks from a game-theoretic point of view. One of the classic models by Fabrikant et al. (2003) is the network creation game, where agents correspond to nodes in a network which buy incident edges for the price of alpha per edge to minimize their total distance to all other nodes. The model is well-studied but still has intriguing open problems. The most famous conjectures state that the price of anarchy is constant for all alpha and that for alpha >= n all equilibrium networks are trees. We introduce a novel technique for analyzing stable networks for high edge-price alpha and employ it to improve on the best known bound for the latter conjecture. In particular we show that for alpha > 4n - 13 all equilibrium networks must be trees, which implies a constant price of anarchy for this range of alpha. Moreover, we also improve the constant upper bound on the price of anarchy for equilibrium trees.
KW - network creation games
KW - price of anarchy
KW - tree conjecture
KW - algorithmic
KW - game theory
Y1 - 2019
U6 - https://doi.org/10.1007/s00224-019-09945-9
SN - 1432-4350
SN - 1433-0490
VL - 64
IS - 3
SP - 422
EP - 443
PB - Springer
CY - New York
ER -
TY - JOUR
A1 - Birnick, Johann
A1 - Bläsius, Thomas
A1 - Friedrich, Tobias
A1 - Naumann, Felix
A1 - Papenbrock, Thorsten
A1 - Schirneck, Friedrich Martin
T1 - Hitting set enumeration with partial information for unique column combination discovery
JF - Proceedings of the VLDB Endowment
N2 - Unique column combinations (UCCs) are a fundamental concept in relational databases. They identify entities in the data and support various data management activities. Still, UCCs are usually not explicitly defined and need to be discovered. State-of-the-art data profiling algorithms are able to efficiently discover UCCs in moderately sized datasets, but they tend to fail on large and, in particular, on wide datasets due to run time and memory limitations.
In this paper, we introduce HPIValid, a novel UCC discovery algorithm that implements a faster and more resource-saving search strategy. HPIValid models the metadata discovery as a hitting set enumeration problem in hypergraphs. In this way, it combines efficient discovery techniques from data profiling research with the most recent theoretical insights into enumeration algorithms. Our evaluation shows that HPIValid is not only orders of magnitude faster than related work, it also has a much smaller memory footprint.
Y1 - 2020
U6 - https://doi.org/10.14778/3407790.3407824
SN - 2150-8097
VL - 13
IS - 11
SP - 2270
EP - 2283
PB - Association for Computing Machinery
CY - [New York, NY]
ER -
TY - GEN
A1 - Björk, Jennie
A1 - Hölze, Katharina
T1 - Editorial
T2 - Creativity and innovation management
Y1 - 2019
U6 - https://doi.org/10.1111/caim.12336
SN - 0963-1690
SN - 1467-8691
VL - 28
IS - 3
SP - 289
EP - 290
PB - Wiley
CY - Hoboken
ER -
TY - JOUR
A1 - Björk, Jennie
A1 - Hölzle, Katharina
A1 - Boer, Harry
T1 - ‘What will we learn from the current crisis?’
JF - Creativity and innovation management
Y1 - 2021
U6 - https://doi.org/10.1111/caim.12442
SN - 0963-1690
SN - 1467-8691
VL - 30
IS - 2
SP - 231
EP - 232
PB - Wiley-Blackwell
CY - Oxford [u.a.]
ER -
TY - JOUR
A1 - Blaesius, Thomas
A1 - Friedrich, Tobias
A1 - Schirneck, Friedrich Martin
T1 - The complexity of dependency detection and discovery in relational databases
JF - Theoretical computer science
N2 - Multi-column dependencies in relational databases come associated with two different computational tasks. The detection problem is to decide whether a dependency of a certain type and size holds in a given database, the discovery problem asks to enumerate all valid dependencies of that type. We settle the complexity of both of these problems for unique column combinations (UCCs), functional dependencies (FDs), and inclusion dependencies (INDs). We show that the detection of UCCs and FDs is W[2]-complete when parameterized by the solution size. The discovery of inclusion-wise minimal UCCs is proven to be equivalent under parsimonious reductions to the transversal hypergraph problem of enumerating the minimal hitting sets of a hypergraph. The discovery of FDs is equivalent to the simultaneous enumeration of the hitting sets of multiple input hypergraphs. We further identify the detection of INDs as one of the first natural W[3]-complete problems. The discovery of maximal INDs is shown to be equivalent to enumerating the maximal satisfying assignments of antimonotone, 3-normalized Boolean formulas.
KW - data profiling
KW - enumeration complexity
KW - functional dependency
KW - inclusion
KW - dependency
KW - parameterized complexity
KW - parsimonious reduction
KW - transversal hypergraph
KW - Unique column combination
KW - W[3]-completeness
Y1 - 2021
U6 - https://doi.org/10.1016/j.tcs.2021.11.020
SN - 0304-3975
SN - 1879-2294
VL - 900
SP - 79
EP - 96
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Bläsius, Thomas
A1 - Freiberger, Cedric
A1 - Friedrich, Tobias
A1 - Katzmann, Maximilian
A1 - Montenegro-Retana, Felix
A1 - Thieffry, Marianne
T1 - Efficient Shortest Paths in Scale-Free Networks with Underlying Hyperbolic Geometry
JF - ACM Transactions on Algorithms
N2 - A standard approach to accelerating shortest path algorithms on networks is the bidirectional search, which explores the graph from the start and the destination, simultaneously. In practice this strategy performs particularly well on scale-free real-world networks. Such networks typically have a heterogeneous degree distribution (e.g., a power-law distribution) and high clustering (i.e., vertices with a common neighbor are likely to be connected themselves). These two properties can be obtained by assuming an underlying hyperbolic geometry.
To explain the observed behavior of the bidirectional search, we analyze its running time on hyperbolic random graphs and prove that it is (O) over tilde (n(2-1/alpha) + n(1/(2 alpha)) + delta(max)) with high probability, where alpha is an element of (1/2, 1) controls the power-law exponent of the degree distribution, and dmax is the maximum degree. This bound is sublinear, improving the obvious worst-case linear bound. Although our analysis depends on the underlying geometry, the algorithm itself is oblivious to it.
KW - Random graphs
KW - hyperbolic geometry
KW - scale-free networks
KW - bidirectional shortest path
Y1 - 2022
U6 - https://doi.org/10.1145/3516483
SN - 1549-6325
SN - 1549-6333
VL - 18
IS - 2
SP - 1
EP - 32
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Bog, Anja
A1 - Plattner, Hasso
A1 - Zeier, Alexander
T1 - A mixed transaction processing and operational reporting benchmark
JF - Information systems frontiers
N2 - The importance of reporting is ever increasing in today's fast-paced market environments and the availability of up-to-date information for reporting has become indispensable. Current reporting systems are separated from the online transaction processing systems (OLTP) with periodic updates pushed in. A pre-defined and aggregated subset of the OLTP data, however, does not provide the flexibility, detail, and timeliness needed for today's operational reporting. As technology advances, this separation has to be re-evaluated and means to study and evaluate new trends in data storage management have to be provided. This article proposes a benchmark for combined OLTP and operational reporting, providing means to evaluate the performance of enterprise data management systems for mixed workloads of OLTP and operational reporting queries. Such systems offer up-to-date information and the flexibility of the entire data set for reporting. We describe how the benchmark provokes the conflicts that are the reason for separating the two workloads on different systems. In this article, we introduce the concepts, logical data schema, transactions and queries of the benchmark, which are entirely based on the original data sets and real workloads of existing, globally operating enterprises.
KW - Benchmarking
KW - Mixed workload
KW - OLTP
KW - Operational reporting
Y1 - 2011
U6 - https://doi.org/10.1007/s10796-010-9283-8
SN - 1387-3326
VL - 13
IS - 3
SP - 321
EP - 335
PB - Springer
CY - Dordrecht
ER -
TY - JOUR
A1 - Bohn, Nicolai
A1 - Kundisch, Dennis
T1 - What are we talking about when we talk about technology pivots?
BT - a Delphi study
JF - Information & management
N2 - Technology pivots were designed to help digital startups make adjustments to the technology underpinning their products and services. While academia and the media make liberal use of the term "technology pivot," they rarely align themselves to Ries' foundational conceptualization. Recent research suggests that a more granulated conceptualization of technology pivots is required. To scientifically derive a comprehensive conceptualization, we conduct a Delphi study with a panel of 38 experts drawn from academia and practice to explore their understanding of "technology pivots." Our study thus makes an important contribution to advance the seminal work by Ries on technology pivots.
KW - digital startup
KW - lean startup approach
KW - technology pivot
KW - conceptualization
KW - Delphi study
Y1 - 2020
U6 - https://doi.org/10.1016/j.im.2020.103319
SN - 0378-7206
SN - 1872-7530
VL - 57
IS - 6
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Boissier, Martin
T1 - Robust and budget-constrained encoding configurations for in-memory database systems
JF - Proceedings of the VLDB Endowment
N2 - Data encoding has been applied to database systems for decades as it mitigates bandwidth bottlenecks and reduces storage requirements. But even in the presence of these advantages, most in-memory database systems use data encoding only conservatively as the negative impact on runtime performance can be severe. Real-world systems with large parts being infrequently accessed and cost efficiency constraints in cloud environments require solutions that automatically and efficiently select encoding techniques, including heavy-weight compression. In this paper, we introduce workload-driven approaches to automaticaly determine memory budget-constrained encoding configurations using greedy heuristics and linear programming. We show for TPC-H, TPC-DS, and the Join Order Benchmark that optimized encoding configurations can reduce the main memory footprint significantly without a loss in runtime performance over state-of-the-art dictionary encoding. To yield robust selections, we extend the linear programming-based approach to incorporate query runtime constraints and mitigate unexpected performance regressions.
KW - General Earth and Planetary Sciences
KW - Water Science and Technology
KW - Geography, Planning and Development
Y1 - 2021
U6 - https://doi.org/10.14778/3503585.3503588
SN - 2150-8097
VL - 15
IS - 4
SP - 780
EP - 793
PB - Association for Computing Machinery (ACM)
CY - [New York]
ER -
TY - JOUR
A1 - Bonifati, Angela
A1 - Mior, Michael J.
A1 - Naumann, Felix
A1 - Noack, Nele Sina
T1 - How inclusive are we?
BT - an analysis of gender diversity in database venues
JF - SIGMOD record / Association for Computing Machinery, Special Interest Group on Management of Data
N2 - ACM SIGMOD, VLDB and other database organizations have committed to fostering an inclusive and diverse community, as do many other scientific organizations. Recently, different measures have been taken to advance these goals, especially for underrepresented groups. One possible measure is double-blind reviewing, which aims to hide gender, ethnicity, and other properties of the authors.
We report the preliminary results of a gender diversity analysis of publications of the database community across several peer-reviewed venues, and also compare women's authorship percentages in both single-blind and double-blind venues along the years. We also obtained a cross comparison of the obtained results in data management with other relevant areas in Computer Science.
Y1 - 2022
U6 - https://doi.org/10.1145/3516431.3516438
SN - 0163-5808
SN - 1943-5835
VL - 50
IS - 4
SP - 30
EP - 35
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Borchert, Florian
A1 - Mock, Andreas
A1 - Tomczak, Aurelie
A1 - Hügel, Jonas
A1 - Alkarkoukly, Samer
A1 - Knurr, Alexander
A1 - Volckmar, Anna-Lena
A1 - Stenzinger, Albrecht
A1 - Schirmacher, Peter
A1 - Debus, Jürgen
A1 - Jäger, Dirk
A1 - Longerich, Thomas
A1 - Fröhling, Stefan
A1 - Eils, Roland
A1 - Bougatf, Nina
A1 - Sax, Ulrich
A1 - Schapranow, Matthieu-Patrick
T1 - Knowledge bases and software support for variant interpretation in precision oncology
JF - Briefings in bioinformatics
N2 - Precision oncology is a rapidly evolving interdisciplinary medical specialty. Comprehensive cancer panels are becoming increasingly available at pathology departments worldwide, creating the urgent need for scalable cancer variant annotation and molecularly informed treatment recommendations. A wealth of mainly academia-driven knowledge bases calls for software tools supporting the multi-step diagnostic process. We derive a comprehensive list of knowledge bases relevant for variant interpretation by a review of existing literature followed by a survey among medical experts from university hospitals in Germany. In addition, we review cancer variant interpretation tools, which integrate multiple knowledge bases. We categorize the knowledge bases along the diagnostic process in precision oncology and analyze programmatic access options as well as the integration of knowledge bases into software tools. The most commonly used knowledge bases provide good programmatic access options and have been integrated into a range of software tools. For the wider set of knowledge bases, access options vary across different parts of the diagnostic process. Programmatic access is limited for information regarding clinical classifications of variants and for therapy recommendations. The main issue for databases used for biological classification of pathogenic variants and pathway context information is the lack of standardized interfaces. There is no single cancer variant interpretation tool that integrates all identified knowledge bases. Specialized tools are available and need to be further developed for different steps in the diagnostic process.
KW - HiGHmed
KW - personalized medicine
KW - molecular tumor board
KW - data integration
KW - cancer therapy
Y1 - 2021
U6 - https://doi.org/10.1093/bib/bbab134
SN - 1467-5463
SN - 1477-4054
VL - 22
IS - 6
PB - Oxford Univ. Press
CY - Oxford
ER -
TY - JOUR
A1 - Borchert, Florian
A1 - Mock, Andreas
A1 - Tomczak, Aurelie
A1 - Hügel, Jonas
A1 - Alkarkoukly, Samer
A1 - Knurr, Alexander
A1 - Volckmar, Anna-Lena
A1 - Stenzinger, Albrecht
A1 - Schirmacher, Peter
A1 - Debus, Jürgen
A1 - Jäger, Dirk
A1 - Longerich, Thomas
A1 - Fröhling, Stefan
A1 - Eils, Roland
A1 - Bougatf, Nina
A1 - Sax, Ulrich
A1 - Schapranow, Matthieu-Patrick
T1 - Correction to: Knowledge bases and software support for variant interpretation in precision oncology
JF - Briefings in bioinformatics
Y1 - 2021
U6 - https://doi.org/10.1093/bib/bbab246
SN - 1467-5463
SN - 1477-4054
VL - 22
IS - 6
PB - Oxford Univ. Press
CY - Oxford
ER -
TY - JOUR
A1 - Buchwald, Sebastian
A1 - Wagelaar, Dennis
A1 - Dan, Li
A1 - Hegedues, Abel
A1 - Herrmannsdoerfer, Markus
A1 - Horn, Tassilo
A1 - Kalnina, Elina
A1 - Krause, Christian
A1 - Lano, Kevin
A1 - Lepper, Markus
A1 - Rensink, Arend
A1 - Rose, Louis
A1 - Waetzoldt, Sebastian
A1 - Mazanek, Steffen
T1 - A survey and comparison of transformation tools based on the transformation tool contest
JF - Science of computer programming
N2 - Model transformation is one of the key tasks in model-driven engineering and relies on the efficient matching and modification of graph-based data structures; its sibling graph rewriting has been used to successfully model problems in a variety of domains. Over the last years, a wide range of graph and model transformation tools have been developed all of them with their own particular strengths and typical application domains. In this paper, we give a survey and a comparison of the model and graph transformation tools that participated at the Transformation Tool Contest 2011. The reader gains an overview of the field and its tools, based on the illustrative solutions submitted to a Hello World task, and a comparison alongside a detailed taxonomy. The article is of interest to researchers in the field of model and graph transformation, as well as to software engineers with a transformation task at hand who have to choose a tool fitting to their needs. All solutions referenced in this article provide a SHARE demo. It supported the peer-review process for the contest, and now allows the reader to test the tools online.
KW - Graph rewriting
KW - Model transformation
KW - Tool survey
KW - Transformation tool contest
Y1 - 2014
U6 - https://doi.org/10.1016/j.scico.2013.10.009
SN - 0167-6423
SN - 1872-7964
VL - 85
SP - 41
EP - 99
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Cabalar, Pedro
A1 - Kaminski, Roland
A1 - Schaub, Torsten H.
A1 - Schuhmann, Anna
T1 - Temporal answer set programming on finite traces
JF - Theory and practice of logic programming
N2 - In this paper, we introduce an alternative approach to Temporal Answer Set Programming that relies on a variation of Temporal Equilibrium Logic (TEL) for finite traces. This approach allows us to even out the expressiveness of TEL over infinite traces with the computational capacity of (incremental) Answer Set Programming (ASP). Also, we argue that finite traces are more natural when reasoning about action and change. As a result, our approach is readily implementable via multi-shot ASP systems and benefits from an extension of ASP's full-fledged input language with temporal operators. This includes future as well as past operators whose combination offers a rich temporal modeling language. For computation, we identify the class of temporal logic programs and prove that it constitutes a normal form for our approach. Finally, we outline two implementations, a generic one and an extension of the ASP system clingo.
Under consideration for publication in Theory and Practice of Logic Programming (TPLP)
Y1 - 2018
U6 - https://doi.org/10.1017/S1471068418000297
SN - 1471-0684
SN - 1475-3081
VL - 18
IS - 3-4
SP - 406
EP - 420
PB - Cambridge Univ. Press
CY - New York
ER -
TY - JOUR
A1 - Caruccio, Loredana
A1 - Deufemia, Vincenzo
A1 - Naumann, Felix
A1 - Polese, Giuseppe
T1 - Discovering relaxed functional dependencies based on multi-attribute dominance
JF - IEEE transactions on knowledge and data engineering
N2 - With the advent of big data and data lakes, data are often integrated from multiple sources. Such integrated data are often of poor quality, due to inconsistencies, errors, and so forth. One way to check the quality of data is to infer functional dependencies (fds). However, in many modern applications it might be necessary to extract properties and relationships that are not captured through fds, due to the necessity to admit exceptions, or to consider similarity rather than equality of data values. Relaxed fds (rfds) have been introduced to meet these needs, but their discovery from data adds further complexity to an already complex problem, also due to the necessity of specifying similarity and validity thresholds. We propose Domino, a new discovery algorithm for rfds that exploits the concept of dominance in order to derive similarity thresholds of attribute values while inferring rfds. An experimental evaluation on real datasets demonstrates the discovery performance and the effectiveness of the proposed algorithm.
KW - Complexity theory
KW - Approximation algorithms
KW - Big Data
KW - Distributed
KW - databases
KW - Semantics
KW - Lakes
KW - Functional dependencies
KW - data profiling
KW - data cleansing
Y1 - 2020
U6 - https://doi.org/10.1109/TKDE.2020.2967722
SN - 1041-4347
SN - 1558-2191
VL - 33
IS - 9
SP - 3212
EP - 3228
PB - Institute of Electrical and Electronics Engineers
CY - New York, NY
ER -
TY - JOUR
A1 - Casel, Katrin
A1 - Fernau, Henning
A1 - Gaspers, Serge
A1 - Gras, Benjamin
A1 - Schmid, Markus L.
T1 - On the complexity of the smallest grammar problem over fixed alphabets
JF - Theory of computing systems
N2 - In the smallest grammar problem, we are given a word w and we want to compute a preferably small context-free grammar G for the singleton language {w} (where the size of a grammar is the sum of the sizes of its rules, and the size of a rule is measured by the length of its right side). It is known that, for unbounded alphabets, the decision variant of this problem is NP-hard and the optimisation variant does not allow a polynomial-time approximation scheme, unless P = NP. We settle the long-standing open problem whether these hardness results also hold for the more realistic case of a constant-size alphabet. More precisely, it is shown that the smallest grammar problem remains NP-complete (and its optimisation version is APX-hard), even if the alphabet is fixed and has size of at least 17. The corresponding reduction is robust in the sense that it also works for an alternative size-measure of grammars that is commonly used in the literature (i. e., a size measure also taking the number of rules into account), and it also allows to conclude that even computing the number of rules required by a smallest grammar is a hard problem. On the other hand, if the number of nonterminals (or, equivalently, the number of rules) is bounded by a constant, then the smallest grammar problem can be solved in polynomial time, which is shown by encoding it as a problem on graphs with interval structure. However, treating the number of rules as a parameter (in terms of parameterised complexity) yields W[1]-hardness. Furthermore, we present an O(3(vertical bar w vertical bar)) exact exponential-time algorithm, based on dynamic programming. These three main questions are also investigated for 1-level grammars, i. e., grammars for which only the start rule contains nonterminals on the right side; thus, investigating the impact of the "hierarchical depth" of grammars on the complexity of the smallest grammar problem. In this regard, we obtain for 1-level grammars similar, but slightly stronger results.
KW - grammar-based compression
KW - smallest grammar problem
KW - straight-line
KW - programs
KW - NP-completeness
KW - exact exponential-time algorithms
Y1 - 2020
U6 - https://doi.org/10.1007/s00224-020-10013-w
SN - 1432-4350
SN - 1433-0490
VL - 65
IS - 2
SP - 344
EP - 409
PB - Springer
CY - New York
ER -
TY - JOUR
A1 - Chan, Lili
A1 - Chaudhary, Kumardeep
A1 - Saha, Aparna
A1 - Chauhan, Kinsuk
A1 - Vaid, Akhil
A1 - Zhao, Shan
A1 - Paranjpe, Ishan
A1 - Somani, Sulaiman
A1 - Richter, Felix
A1 - Miotto, Riccardo
A1 - Lala, Anuradha
A1 - Kia, Arash
A1 - Timsina, Prem
A1 - Li, Li
A1 - Freeman, Robert
A1 - Chen, Rong
A1 - Narula, Jagat
A1 - Just, Allan C.
A1 - Horowitz, Carol
A1 - Fayad, Zahi
A1 - Cordon-Cardo, Carlos
A1 - Schadt, Eric
A1 - Levin, Matthew A.
A1 - Reich, David L.
A1 - Fuster, Valentin
A1 - Murphy, Barbara
A1 - He, John C.
A1 - Charney, Alexander W.
A1 - Böttinger, Erwin
A1 - Glicksberg, Benjamin
A1 - Coca, Steven G.
A1 - Nadkarni, Girish N.
T1 - AKI in hospitalized patients with COVID-19
JF - Journal of the American Society of Nephrology : JASN
N2 - Background:
Early reports indicate that AKI is common among patients with coronavirus disease 2019 (COVID-19) and associatedwith worse outcomes. However, AKI among hospitalized patients with COVID19 in the United States is not well described.
Methods:
This retrospective, observational study involved a review of data from electronic health records of patients aged >= 18 years with laboratory-confirmed COVID-19 admitted to the Mount Sinai Health System from February 27 to May 30, 2020. We describe the frequency of AKI and dialysis requirement, AKI recovery, and adjusted odds ratios (aORs) with mortality.
Results:
Of 3993 hospitalized patients with COVID-19, AKI occurred in 1835 (46%) patients; 347 (19%) of the patientswith AKI required dialysis. The proportionswith stages 1, 2, or 3 AKIwere 39%, 19%, and 42%, respectively. A total of 976 (24%) patients were admitted to intensive care, and 745 (76%) experienced AKI. Of the 435 patients with AKI and urine studies, 84% had proteinuria, 81% had hematuria, and 60% had leukocyturia. Independent predictors of severe AKI were CKD, men, and higher serum potassium at admission. In-hospital mortality was 50% among patients with AKI versus 8% among those without AKI (aOR, 9.2; 95% confidence interval, 7.5 to 11.3). Of survivors with AKI who were discharged, 35% had not recovered to baseline kidney function by the time of discharge. An additional 28 of 77 (36%) patients who had not recovered kidney function at discharge did so on posthospital follow-up.
Conclusions:
AKI is common among patients hospitalized with COVID-19 and is associated with high mortality. Of all patients with AKI, only 30% survived with recovery of kidney function by the time of discharge.
KW - acute renal failure
KW - clinical nephrology
KW - dialysis
KW - COVID-19
Y1 - 2021
U6 - https://doi.org/10.1681/ASN.2020050615
SN - 1046-6673
SN - 1533-3450
VL - 32
IS - 1
SP - 151
EP - 160
PB - American Society of Nephrology
CY - Washington
ER -
TY - JOUR
A1 - Chan, Lili
A1 - Jaladanki, Suraj K.
A1 - Somani, Sulaiman
A1 - Paranjpe, Ishan
A1 - Kumar, Arvind
A1 - Zhao, Shan
A1 - Kaufman, Lewis
A1 - Leisman, Staci
A1 - Sharma, Shuchita
A1 - He, John Cijiang
A1 - Murphy, Barbara
A1 - Fayad, Zahi A.
A1 - Levin, Matthew A.
A1 - Böttinger, Erwin
A1 - Charney, Alexander W.
A1 - Glicksberg, Benjamin
A1 - Coca, Steven G.
A1 - Nadkarni, Girish N.
T1 - Outcomes of patients on maintenance dialysis hospitalized with COVID-19
JF - Clinical journal of the American Society of Nephrology : CJASN
KW - chronic dialysis
KW - COVID-19
KW - end-stage kidney disease
Y1 - 2021
U6 - https://doi.org/10.2215/CJN.12360720
SN - 1555-9041
SN - 1555-905X
VL - 16
IS - 3
SP - 452
EP - 455
PB - American Society of Nephrology
CY - Washington
ER -
TY - JOUR
A1 - Chauhan, Ankit
A1 - Friedrich, Tobias
A1 - Rothenberger, Ralf
T1 - Greed is good for deterministic scale-free networks
JF - Algorithmica : an international journal in computer science
N2 - Large real-world networks typically follow a power-law degree distribution. To study such networks, numerous random graph models have been proposed. However, real-world networks are not drawn at random. Therefore, Brach et al. (27th symposium on discrete algorithms (SODA), pp 1306-1325, 2016) introduced two natural deterministic conditions: (1) a power-law upper bound on the degree distribution (PLB-U) and (2) power-law neighborhoods, that is, the degree distribution of neighbors of each vertex is also upper bounded by a power law (PLB-N). They showed that many real-world networks satisfy both properties and exploit them to design faster algorithms for a number of classical graph problems. We complement their work by showing that some well-studied random graph models exhibit both of the mentioned PLB properties. PLB-U and PLB-N hold with high probability for Chung-Lu Random Graphs and Geometric Inhomogeneous Random Graphs and almost surely for Hyperbolic Random Graphs. As a consequence, all results of Brach et al. also hold with high probability or almost surely for those random graph classes. In the second part we study three classical NP-hard optimization problems on PLB networks. It is known that on general graphs with maximum degree Delta, a greedy algorithm, which chooses nodes in the order of their degree, only achieves a Omega (ln Delta)-approximation forMinimum Vertex Cover and Minimum Dominating Set, and a Omega(Delta)-approximation forMaximum Independent Set. We prove that the PLB-U property with beta>2 suffices for the greedy approach to achieve a constant-factor approximation for all three problems. We also show that these problems are APX-hard even if PLB-U, PLB-N, and an additional power-law lower bound on the degree distribution hold. Hence, a PTAS cannot be expected unless P = NP. Furthermore, we prove that all three problems are in MAX SNP if the PLB-U property holds.
KW - random graphs
KW - deterministic properties
KW - power-law
KW - approximation
KW - APX-hardness
Y1 - 2020
U6 - https://doi.org/10.1007/s00453-020-00729-z
SN - 0178-4617
SN - 1432-0541
VL - 82
IS - 11
SP - 3338
EP - 3389
PB - Springer
CY - New York
ER -
TY - JOUR
A1 - Chromik, Jonas
A1 - Kirsten, Kristina
A1 - Herdick, Arne
A1 - Kappattanavar, Arpita Mallikarjuna
A1 - Arnrich, Bert
T1 - SensorHub
BT - Multimodal sensing in real-life enables home-based studies
JF - Sensors
N2 - Observational studies are an important tool for determining whether the findings from controlled experiments can be transferred into scenarios that are closer to subjects' real-life circumstances. A rigorous approach to observational studies involves collecting data from different sensors to comprehensively capture the situation of the subject. However, this leads to technical difficulties especially if the sensors are from different manufacturers, as multiple data collection tools have to run simultaneously. We present SensorHub, a system that can collect data from various wearable devices from different manufacturers, such as inertial measurement units, portable electrocardiographs, portable electroencephalographs, portable photoplethysmographs, and sensors for electrodermal activity. Additionally, our tool offers the possibility to include ecological momentary assessments (EMAs) in studies. Hence, SensorHub enables multimodal sensor data collection under real-world conditions and allows direct user feedback to be collected through questionnaires, enabling studies at home. In a first study with 11 participants, we successfully used SensorHub to record multiple signals with different devices and collected additional information with the help of EMAs. In addition, we evaluated SensorHub's technical capabilities in several trials with up to 21 participants recording simultaneously using multiple sensors with sampling frequencies as high as 1000 Hz. We could show that although there is a theoretical limitation to the transmissible data rate, in practice this limitation is not an issue and data loss is rare. We conclude that with modern communication protocols and with the increasingly powerful smartphones and wearables, a system like our SensorHub establishes an interoperability framework to adequately combine consumer-grade sensing hardware which enables observational studies in real life.
KW - multimodal sensing
KW - home-based studies
KW - activity recognition
KW - sensor
KW - systems
KW - ecological momentary assessment
KW - digital health
Y1 - 2022
U6 - https://doi.org/10.3390/s22010408
SN - 1424-8220
VL - 22
IS - 1
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Chromik, Jonas
A1 - Pirl, Lukas
A1 - Beilharz, Jossekin Jakob
A1 - Arnrich, Bert
A1 - Polze, Andreas
T1 - Certainty in QRS detection with artificial neural networks
JF - Biomedical signal processing and control
N2 - Detection of the QRS complex is a long-standing topic in the context of electrocardiography and many algorithms build upon the knowledge of the QRS positions. Although the first solutions to this problem were proposed in the 1970s and 1980s, there is still potential for improvements. Advancements in neural network technology made in recent years also lead to the emergence of enhanced QRS detectors based on artificial neural networks. In this work, we propose a method for assessing the certainty that is in each of the detected QRS complexes, i.e. how confident the QRS detector is that there is, in fact, a QRS complex in the position where it was detected. We further show how this metric can be utilised to distinguish correctly detected QRS complexes from false detections.
KW - QRS detection
KW - Electrocardiography
KW - Artificial neural networks
KW - Machine
KW - learning
KW - Signal-to-noise ratio
Y1 - 2021
U6 - https://doi.org/10.1016/j.bspc.2021.102628
SN - 1746-8094
SN - 1746-8108
VL - 68
PB - Elsevier
CY - Oxford
ER -
TY - JOUR
A1 - Chujfi-La-Roche, Salim
A1 - Meinel, Christoph
T1 - Matching cognitively sympathetic individual styles to develop collective intelligence in digital communities
JF - AI & society : the journal of human-centred systems and machine intelligence
N2 - Creation, collection and retention of knowledge in digital communities is an activity that currently requires being explicitly targeted as a secure method of keeping intellectual capital growing in the digital era. In particular, we consider it relevant to analyze and evaluate the empathetic cognitive personalities and behaviors that individuals now have with the change from face-to-face communication (F2F) to computer-mediated communication (CMC) online. This document proposes a cyber-humanistic approach to enhance the traditional SECI knowledge management model. A cognitive perception is added to its cyclical process following design thinking interaction, exemplary for improvement of the method in which knowledge is continuously created, converted and shared. In building a cognitive-centered model, we specifically focus on the effective identification and response to cognitive stimulation of individuals, as they are the intellectual generators and multiplicators of knowledge in the online environment. Our target is to identify how geographically distributed-digital-organizations should align the individual's cognitive abilities to promote iteration and improve interaction as a reliable stimulant of collective intelligence. The new model focuses on analyzing the four different stages of knowledge processing, where individuals with sympathetic cognitive personalities can significantly boost knowledge creation in a virtual social system. For organizations, this means that multidisciplinary individuals can maximize their extensive potential, by externalizing their knowledge in the correct stage of the knowledge creation process, and by collaborating with their appropriate sympathetically cognitive remote peers.
KW - argumentation research
KW - cyber humanistic
KW - cognition
KW - collaboration
KW - knowledge building
KW - knowledge management
KW - teamwork
KW - virtual groups
Y1 - 2017
U6 - https://doi.org/10.1007/s00146-017-0780-x
SN - 0951-5666
SN - 1435-5655
VL - 35
IS - 1
SP - 5
EP - 15
PB - Springer
CY - New York
ER -
TY - JOUR
A1 - Cope, Justin L.
A1 - Baukmann, Hannes A.
A1 - Klinger, Jörn E.
A1 - Ravarani, Charles N. J.
A1 - Böttinger, Erwin
A1 - Konigorski, Stefan
A1 - Schmidt, Marco F.
T1 - Interaction-based feature selection algorithm outperforms polygenic risk score in predicting Parkinson’s Disease status
JF - Frontiers in genetics
N2 - Polygenic risk scores (PRS) aggregating results from genome-wide association studies are the state of the art in the prediction of susceptibility to complex traits or diseases, yet their predictive performance is limited for various reasons, not least of which is their failure to incorporate the effects of gene-gene interactions. Novel machine learning algorithms that use large amounts of data promise to find gene-gene interactions in order to build models with better predictive performance than PRS. Here, we present a data preprocessing step by using data-mining of contextual information to reduce the number of features, enabling machine learning algorithms to identify gene-gene interactions. We applied our approach to the Parkinson's Progression Markers Initiative (PPMI) dataset, an observational clinical study of 471 genotyped subjects (368 cases and 152 controls). With an AUC of 0.85 (95% CI = [0.72; 0.96]), the interaction-based prediction model outperforms the PRS (AUC of 0.58 (95% CI = [0.42; 0.81])). Furthermore, feature importance analysis of the model provided insights into the mechanism of Parkinson's disease. For instance, the model revealed an interaction of previously described drug target candidate genes TMEM175 and GAPDHP25. These results demonstrate that interaction-based machine learning models can improve genetic prediction models and might provide an answer to the missing heritability problem.
KW - epistasis
KW - machine learning
KW - feature selection
KW - parkinson's disease
KW - PPMI (parkinson's progression markers initiative)
Y1 - 2021
U6 - https://doi.org/10.3389/fgene.2021.744557
SN - 1664-8021
VL - 12
PB - Frontiers Media
CY - Lausanne
ER -
TY - JOUR
A1 - Cseh, Agnes
A1 - Heeger, Klaus
T1 - The stable marriage problem with ties and restricted edges
JF - Discrete optimization
N2 - In the stable marriage problem, a set of men and a set of women are given, each of whom has a strictly ordered preference list over the acceptable agents in the opposite class. A matching is called stable if it is not blocked by any pair of agents, who mutually prefer each other to their respective partner. Ties in the preferences allow for three different definitions for a stable matching: weak, strong and super-stability. Besides this, acceptable pairs in the instance can be restricted in their ability of blocking a matching or being part of it, which again generates three categories of restrictions on acceptable pairs. Forced pairs must be in a stable matching, forbidden pairs must not appear in it, and lastly, free pairs cannot block any matching.
Our computational complexity study targets the existence of a stable solution for each of the three stability definitions, in the presence of each of the three types of restricted pairs. We solve all cases that were still open. As a byproduct, we also derive that the maximum size weakly stable matching problem is hard even in very dense graphs, which may be of independent interest.
KW - stable matchings
KW - restricted edges
KW - complexity
Y1 - 2020
U6 - https://doi.org/10.1016/j.disopt.2020.100571
SN - 1572-5286
SN - 1873-636X
VL - 36
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Cseh, Ágnes
A1 - Fleiner, Tamas
T1 - The complexity of cake cutting with unequal shares
JF - ACM transactions on algorithms : TALG
N2 - An unceasing problem of our prevailing society is the fair division of goods. The problem of proportional cake cutting focuses on dividing a heterogeneous and divisible resource, the cake, among n players who value pieces according to their own measure function. The goal is to assign each player a not necessarily connected part of the cake that the player evaluates at least as much as her proportional share.
In this article, we investigate the problem of proportional division with unequal shares, where each player is entitled to receive a predetermined portion of the cake. Our main contribution is threefold. First we present a protocol for integer demands, which delivers a proportional solution in fewer queries than all known protocols. By giving a matching lower bound, we then show that our protocol is asymptotically the fastest possible. Finally, we turn to irrational demands and solve the proportional cake cutting problem by reducing it to the same problem with integer demands only. All results remain valid in a highly general cake cutting model, which can be of independent interest.
KW - Cake cutting
KW - fair division
KW - unequal shares
KW - proportional division
Y1 - 2020
U6 - https://doi.org/10.1145/3380742
SN - 1549-6325
SN - 1549-6333
VL - 16
IS - 3
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Datta, Suparno
A1 - Sachs, Jan Philipp
A1 - Freitas da Cruz, Harry
A1 - Martensen, Tom
A1 - Bode, Philipp
A1 - Morassi Sasso, Ariane
A1 - Glicksberg, Benjamin S.
A1 - Böttinger, Erwin
T1 - FIBER
BT - enabling flexible retrieval of electronic health records data for clinical predictive modeling
JF - JAMIA open
N2 - Objectives:
The development of clinical predictive models hinges upon the availability of comprehensive clinical data. Tapping into such resources requires considerable effort from clinicians, data scientists, and engineers. Specifically, these efforts are focused on data extraction and preprocessing steps required prior to modeling, including complex database queries. A handful of software libraries exist that can reduce this complexity by building upon data standards. However, a gap remains concerning electronic health records (EHRs) stored in star schema clinical data warehouses, an approach often adopted in practice. In this article, we introduce the FlexIBle EHR Retrieval (FIBER) tool: a Python library built on top of a star schema (i2b2) clinical data warehouse that enables flexible generation of modeling-ready cohorts as data frames.
Materials and Methods:
FIBER was developed on top of a large-scale star schema EHR database which contains data from 8 million patients and over 120 million encounters. To illustrate FIBER's capabilities, we present its application by building a heart surgery patient cohort with subsequent prediction of acute kidney injury (AKI) with various machine learning models.
Results:
Using FIBER, we were able to build the heart surgery cohort (n = 12 061), identify the patients that developed AKI (n = 1005), and automatically extract relevant features (n = 774). Finally, we trained machine learning models that achieved area under the curve values of up to 0.77 for this exemplary use case.
Conclusion:
FIBER is an open-source Python library developed for extracting information from star schema clinical data warehouses and reduces time-to-modeling, helping to streamline the clinical modeling process.
KW - databases
KW - factual
KW - electronic health records
KW - information storage and
KW - retrieval
KW - workflow
KW - software/instrumentation
Y1 - 2021
U6 - https://doi.org/10.1093/jamiaopen/ooab048
SN - 2574-2531
VL - 4
IS - 3
PB - Oxford Univ. Press
CY - Oxford
ER -
TY - JOUR
A1 - De Freitas, Jessica K.
A1 - Johnson, Kipp W.
A1 - Golden, Eddye
A1 - Nadkarni, Girish N.
A1 - Dudley, Joel T.
A1 - Böttinger, Erwin
A1 - Glicksberg, Benjamin S.
A1 - Miotto, Riccardo
T1 - Phe2vec
BT - Automated disease phenotyping based on unsupervised embeddings from electronic health records
JF - Patterns
N2 - Robust phenotyping of patients from electronic health records (EHRs) at scale is a challenge in clinical informatics. Here, we introduce Phe2vec, an automated framework for disease phenotyping from EHRs based on unsupervised learning and assess its effectiveness against standard rule-based algorithms from Phenotype KnowledgeBase (PheKB). Phe2vec is based on pre-computing embeddings of medical concepts and patients' clinical history. Disease phenotypes are then derived from a seed concept and its neighbors in the embedding space. Patients are linked to a disease if their embedded representation is close to the disease phenotype. Comparing Phe2vec and PheKB cohorts head-to-head using chart review, Phe2vec performed on par or better in nine out of ten diseases. Differently from other approaches, it can scale to any condition and was validated against widely adopted expert-based standards. Phe2vec aims to optimize clinical informatics research by augmenting current frameworks to characterize patients by condition and derive reliable disease cohorts.
Y1 - 2021
U6 - https://doi.org/10.1016/j.patter.2021.100337
SN - 2666-3899
VL - 2
IS - 9
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Decker, Gero
A1 - Kopp, Oliver
A1 - Leymann, Frank
A1 - Weske, Mathias
T1 - Interacting services : from specification to execution
N2 - Interacting services play a key role to realize business process integration among different business partners by means of electronic message exchange. In order to provide seamless integration of these services, the messages exchanged as well as their dependencies must be well-defined. Service choreographies are a means to describe the allowed conversations. This article presents a requirements framework for service choreography languages, along which existing choreography languages are assessed. The requirements framework provides the basis for introducing the language BPEL4Chor, which extends the industry standard WS-BPEL with choreography-specific concepts. A validation is provided and integration with executable service orchestrations is discussed.
Y1 - 2009
UR - http://www.sciencedirect.com/science/journal/0169023X
U6 - https://doi.org/10.1016/j.datak.2009.04.003
SN - 0169-023X
ER -
TY - JOUR
A1 - Decker, Gero
A1 - Mendling, Jan
T1 - Process instantiation
N2 - Although several process modeling languages allow one to specify processes with multiple start elements, the precise semantics of such models are often unclear, both from a pragmatic and from a theoretical point of view. This paper addresses the lack of research on this problem and introduces the CASU framework (from Creation, Activation, subscription, Unsubscription). The contribution of this framework is a systematic description of design alternatives for the specification of instantiation semantics of process modeling languages. We classify six prominent languages by the help of this framework. We validate the relevance of the CASU framework through empirical investigations involving a large set of process models from practice. Our work provides the basis for the design of new correctness criteria as well as for the formalization of Event-driven Process Chains (EPCs) and extension of the Business Process Modeling Notation (BPMN). It complements research such as the workflow patterns.
Y1 - 2009
UR - http://www.sciencedirect.com/science/journal/0169023X
U6 - https://doi.org/10.1016/j.datak.2009.02.013
SN - 0169-023X
ER -
TY - JOUR
A1 - Decker, Gero
A1 - Weske, Mathias
T1 - Interaction-centric modeling of process choreographies
JF - Information systems
N2 - With the rise of electronic integration between organizations, the need for a precise specification of interaction behavior increases. Information systems, replacing interaction previously carried out by humans via phone, faxes and emails, require a precise specification for handling all possible situations. Such interaction behavior is described in process choreographies. While many proposals for choreography languages have already been made, most of them fall into the category of interconnection models, where the observable behavior of the different partners is described and then related via message flow. As this article will show, this modeling approach fails to support fundamental design principles of choreographies and typically leads to modeling errors. This motivates an alternative modeling style, namely interaction modeling, for overcoming these limitations. While the main concepts are independent of a concrete modeling language, iBPMN is introduced as novel interaction modeling language. Formal execution semantics are provided and a comprehensive toolset implementing the approach is presented.
KW - Choreographies
KW - B2B process integration
KW - Interaction modeling
KW - Business Process Modeling Notation
Y1 - 2011
U6 - https://doi.org/10.1016/j.is.2010.06.005
SN - 0306-4379
VL - 36
IS - 2
SP - 292
EP - 312
PB - Elsevier
CY - Oxford
ER -
TY - JOUR
A1 - Dellepiane, Sergio
A1 - Vaid, Akhil
A1 - Jaladanki, Suraj K.
A1 - Coca, Steven
A1 - Fayad, Zahi A.
A1 - Charney, Alexander W.
A1 - Böttinger, Erwin
A1 - He, John Cijiang
A1 - Glicksberg, Benjamin S.
A1 - Chan, Lili
A1 - Nadkarni, Girish
T1 - Acute kidney injury in patients hospitalized with COVID-19 in New York City
BT - Temporal Trends From March 2020 to April 2021
JF - Kidney medicine
Y1 - 2021
U6 - https://doi.org/10.1016/j.xkme.2021.06.008
SN - 2590-0595
VL - 3
IS - 5
SP - 877
EP - 879
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Discher, Sören
A1 - Richter, Rico
A1 - Döllner, Jürgen Roland Friedrich
T1 - Concepts and techniques for web-based visualization and processing of massive 3D point clouds with semantics
JF - Graphical Models
N2 - 3D point cloud technology facilitates the automated and highly detailed acquisition of real-world environments such as assets, sites, and countries. We present a web-based system for the interactive exploration and inspection of arbitrary large 3D point clouds. Our approach is able to render 3D point clouds with billions of points using spatial data structures and level-of-detail representations. Point-based rendering techniques and post-processing effects are provided to enable task-specific and data-specific filtering, e.g., based on semantics. A set of interaction techniques allows users to collaboratively work with the data (e.g., measuring distances and annotating). Additional value is provided by the system’s ability to display additional, context-providing geodata alongside 3D point clouds and to integrate processing and analysis operations. We have evaluated the presented techniques and in case studies and with different data sets from aerial, mobile, and terrestrial acquisition with up to 120 billion points to show their practicality and feasibility.
KW - 3D Point clouds
KW - Web-based rendering
KW - Point-based rendering
KW - Processing strategies
Y1 - 2019
U6 - https://doi.org/10.1016/j.gmod.2019.101036
SN - 1524-0703
SN - 1524-0711
VL - 104
PB - Elsevier
CY - San Diego
ER -
TY - JOUR
A1 - Discher, Sören
A1 - Richter, Rico
A1 - Döllner, Jürgen Roland Friedrich
T1 - Interactive and View-Dependent See-Through Lenses for Massive 3D Point Clouds
JF - Advances in 3D Geoinformation
N2 - 3D point clouds are a digital representation of our world and used in a variety of applications. They are captured with LiDAR or derived by image-matching approaches to get surface information of objects, e.g., indoor scenes, buildings, infrastructures, cities, and landscapes. We present novel interaction and visualization techniques for heterogeneous, time variant, and semantically rich 3D point clouds. Interactive and view-dependent see-through lenses are introduced as exploration tools to enhance recognition of objects, semantics, and temporal changes within 3D point cloud depictions. We also develop filtering and highlighting techniques that are used to dissolve occlusion to give context-specific insights. All techniques can be combined with an out-of-core real-time rendering system for massive 3D point clouds. We have evaluated the presented approach with 3D point clouds from different application domains. The results show the usability and how different visualization and exploration tasks can be improved for a variety of domain-specific applications.
KW - 3D point clouds
KW - LIDAR
KW - Visualization
KW - Point-based rendering
Y1 - 2016
SN - 978-3-319-25691-7
SN - 978-3-319-25689-4
U6 - https://doi.org/10.1007/978-3-319-25691-7_3
SN - 1863-2246
SP - 49
EP - 62
PB - Springer
CY - Cham
ER -
TY - JOUR
A1 - Doerr, Benjamin
A1 - Krejca, Martin S.
T1 - Significance-based estimation-of-distribution algorithms
JF - IEEE transactions on evolutionary computation
N2 - Estimation-of-distribution algorithms (EDAs) are randomized search heuristics that create a probabilistic model of the solution space, which is updated iteratively, based on the quality of the solutions sampled according to the model. As previous works show, this iteration-based perspective can lead to erratic updates of the model, in particular, to bit-frequencies approaching a random boundary value. In order to overcome this problem, we propose a new EDA based on the classic compact genetic algorithm (cGA) that takes into account a longer history of samples and updates its model only with respect to information which it classifies as statistically significant. We prove that this significance-based cGA (sig-cGA) optimizes the commonly regarded benchmark functions OneMax (OM), LeadingOnes, and BinVal all in quasilinear time, a result shown for no other EDA or evolutionary algorithm so far. For the recently proposed stable compact genetic algorithm-an EDA that tries to prevent erratic model updates by imposing a bias to the uniformly distributed model-we prove that it optimizes OM only in a time exponential in its hypothetical population size. Similarly, we show that the convex search algorithm cannot optimize OM in polynomial time.
KW - heuristic algorithms
KW - sociology
KW - statistics
KW - history
KW - probabilistic
KW - logic
KW - benchmark testing
KW - genetic algorithms
KW - estimation-of-distribution
KW - algorithm (EDA)
KW - run time analysis
KW - theory
Y1 - 2020
U6 - https://doi.org/10.1109/TEVC.2019.2956633
SN - 1089-778X
SN - 1941-0026
VL - 24
IS - 6
SP - 1025
EP - 1034
PB - Institute of Electrical and Electronics Engineers
CY - New York, NY
ER -
TY - JOUR
A1 - Doerr, Benjamin
A1 - Krejca, Martin Stefan
T1 - A simplified run time analysis of the univariate marginal distribution algorithm on LeadingOnes
JF - Theoretical computer science
N2 - With elementary means, we prove a stronger run time guarantee for the univariate marginal distribution algorithm (UMDA) optimizing the LEADINGONES benchmark function in the desirable regime with low genetic drift. If the population size is at least quasilinear, then, with high probability, the UMDA samples the optimum in a number of iterations that is linear in the problem size divided by the logarithm of the UMDA's selection rate. This improves over the previous guarantee, obtained by Dang and Lehre (2015) via the deep level-based population method, both in terms of the run time and by demonstrating further run time gains from small selection rates. Under similar assumptions, we prove a lower bound that matches our upper bound up to constant factors.
KW - Theory
KW - Estimation-of-distribution algorithm
KW - Run time analysis
Y1 - 2021
U6 - https://doi.org/10.1016/j.tcs.2020.11.028
SN - 0304-3975
SN - 1879-2294
VL - 851
SP - 121
EP - 128
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Doerr, Benjamin
A1 - Kötzing, Timo
T1 - Lower bounds from fitness levels made easy
JF - Algorithmica
N2 - One of the first and easy to use techniques for proving run time bounds for evolutionary algorithms is the so-called method of fitness levels by Wegener. It uses a partition of the search space into a sequence of levels which are traversed by the algorithm in increasing order, possibly skipping levels. An easy, but often strong upper bound for the run time can then be derived by adding the reciprocals of the probabilities to leave the levels (or upper bounds for these). Unfortunately, a similarly effective method for proving lower bounds has not yet been established. The strongest such method, proposed by Sudholt (2013), requires a careful choice of the viscosity parameters gamma(i), j, 0 <= i < j <= n. In this paper we present two new variants of the method, one for upper and one for lower bounds. Besides the level leaving probabilities, they only rely on the probabilities that levels are visited at all. We show that these can be computed or estimated without greater difficulties and apply our method to reprove the following known results in an easy and natural way. (i) The precise run time of the (1+1) EA on LEADINGONES. (ii) A lower bound for the run time of the (1+1) EA on ONEMAX, tight apart from an O(n) term. (iii) A lower bound for the run time of the (1+1) EA on long k-paths (which differs slightly from the previous result due to a small error in the latter). We also prove a tighter lower bound for the run time of the (1+1) EA on jump functions by showing that, regardless of the jump size, only with probability O(2(-n)) the algorithm can avoid to jump over the valley of low fitness.
KW - First hitting time
KW - Fitness level method
KW - Evolutionary computation
Y1 - 2022
U6 - https://doi.org/10.1007/s00453-022-00952-w
SN - 0178-4617
SN - 1432-0541
PB - Springer
CY - New York
ER -
TY - JOUR
A1 - Doerr, Benjamin
A1 - Kötzing, Timo
A1 - Lagodzinski, Gregor J. A.
A1 - Lengler, Johannes
T1 - The impact of lexicographic parsimony pressure for ORDER/MAJORITY on the run time
JF - Theoretical computer science : the journal of the EATCS
N2 - While many optimization problems work with a fixed number of decision variables and thus a fixed-length representation of possible solutions, genetic programming (GP) works on variable-length representations. A naturally occurring problem is that of bloat, that is, the unnecessary growth of solution lengths, which may slow down the optimization process. So far, the mathematical runtime analysis could not deal well with bloat and required explicit assumptions limiting bloat.
In this paper, we provide the first mathematical runtime analysis of a GP algorithm that does not require any assumptions on the bloat. Previous performance guarantees were only proven conditionally for runs in which no strong bloat occurs. Together with improved analyses for the case with bloat restrictions our results show that such assumptions on the bloat are not necessary and that the algorithm is efficient without explicit bloat control mechanism.
More specifically, we analyzed the performance of the (1 + 1) GP on the two benchmark functions ORDER and MAJORITY. When using lexicographic parsimony pressure as bloat control, we show a tight runtime estimate of O(T-init + nlogn) iterations both for ORDER and MAJORITY. For the case without bloat control, the bounds O(T-init logT(i)(nit) + n(logn)(3)) and Omega(T-init + nlogn) (and Omega(T-init log T-init) for n = 1) hold for MAJORITY(1).
KW - genetic programming
KW - bloat control
KW - theory
KW - runtime analysis
Y1 - 2020
U6 - https://doi.org/10.1016/j.tcs.2020.01.011
SN - 0304-3975
SN - 1879-2294
VL - 816
SP - 144
EP - 168
PB - Elsevier
CY - Amsterdam [u.a.]
ER -
TY - JOUR
A1 - Doerr, Benjamin
A1 - Neumann, Frank
A1 - Sutton, Andrew M.
T1 - Time Complexity Analysis of Evolutionary Algorithms on Random Satisfiable k-CNF Formulas
JF - Algorithmica : an international journal in computer science
N2 - We contribute to the theoretical understanding of randomized search heuristics by investigating their optimization behavior on satisfiable random k-satisfiability instances both in the planted solution model and the uniform model conditional on satisfiability. Denoting the number of variables by n, our main technical result is that the simple () evolutionary algorithm with high probability finds a satisfying assignment in time when the clause-variable density is at least logarithmic. For low density instances, evolutionary algorithms seem to be less effective, and all we can show is a subexponential upper bound on the runtime for densities below . We complement these mathematical results with numerical experiments on a broader density spectrum. They indicate that, indeed, the () EA is less efficient on lower densities. Our experiments also suggest that the implicit constants hidden in our main runtime guarantee are low. Our main result extends and considerably improves the result obtained by Sutton and Neumann (Lect Notes Comput Sci 8672:942-951, 2014) in terms of runtime, minimum density, and clause length. These improvements are made possible by establishing a close fitness-distance correlation in certain parts of the search space. This approach might be of independent interest and could be useful for other average-case analyses of randomized search heuristics. While the notion of a fitness-distance correlation has been around for a long time, to the best of our knowledge, this is the first time that fitness-distance correlation is explicitly used to rigorously prove a performance statement for an evolutionary algorithm.
KW - Runtime analysis
KW - Satisfiability
KW - Fitness-distance correlation
Y1 - 2016
U6 - https://doi.org/10.1007/s00453-016-0190-3
SN - 0178-4617
SN - 1432-0541
VL - 78
SP - 561
EP - 586
PB - Springer
CY - New York
ER -
TY - JOUR
A1 - Draisbach, Uwe
A1 - Christen, Peter
A1 - Naumann, Felix
T1 - Transforming pairwise duplicates to entity clusters for high-quality duplicate detection
JF - ACM Journal of Data and Information Quality
N2 - Duplicate detection algorithms produce clusters of database records, each cluster representing a single real-world entity. As most of these algorithms use pairwise comparisons, the resulting (transitive) clusters can be inconsistent: Not all records within a cluster are sufficiently similar to be classified as duplicate. Thus, one of many subsequent clustering algorithms can further improve the result.
We explain in detail, compare, and evaluate many of these algorithms and introduce three new clustering algorithms in the specific context of duplicate detection. Two of our three new algorithms use the structure of the input graph to create consistent clusters. Our third algorithm, and many other clustering algorithms, focus on the edge weights, instead. For evaluation, in contrast to related work, we experiment on true real-world datasets, and in addition examine in great detail various pair-selection strategies used in practice. While no overall winner emerges, we are able to identify best approaches for different situations. In scenarios with larger clusters, our proposed algorithm, Extended Maximum Clique Clustering (EMCC), and Markov Clustering show the best results. EMCC especially outperforms Markov Clustering regarding the precision of the results and additionally has the advantage that it can also be used in scenarios where edge weights are not available.
KW - Record linkage
KW - data matching
KW - entity resolution
KW - deduplication
KW - clustering
Y1 - 2019
U6 - https://doi.org/10.1145/3352591
SN - 1936-1955
SN - 1936-1963
VL - 12
IS - 1
SP - 1
EP - 30
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Dreseler, Markus
A1 - Boissier, Martin
A1 - Rabl, Tilmann
A1 - Uflacker, Matthias
T1 - Quantifying TPC-H choke points and their optimizations
JF - Proceedings of the VLDB Endowment
N2 - TPC-H continues to be the most widely used benchmark for relational OLAP systems. It poses a number of challenges, also known as "choke points", which database systems have to solve in order to achieve good benchmark results. Examples include joins across multiple tables, correlated subqueries, and correlations within the TPC-H data set. Knowing the impact of such optimizations helps in developing optimizers as well as in interpreting TPC-H results across database systems.
This paper provides a systematic analysis of choke points and their optimizations. It complements previous work on TPC-H choke points by providing a quantitative discussion of their relevance. It focuses on eleven choke points where the optimizations are beneficial independently of the database system. Of these, the flattening of subqueries and the placement of predicates have the biggest impact. Three queries (Q2, Q17, and Q21) are strongly ifluenced by the choice of an efficient query plan; three others (Q1, Q13, and Q18) are less influenced by plan optimizations and more dependent on an efficient execution engine.
Y1 - 2020
U6 - https://doi.org/10.14778/3389133.3389138
SN - 2150-8097
VL - 13
IS - 8
SP - 1206
EP - 1220
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Drimalla, Hanna
A1 - Landwehr, Niels
A1 - Hess, Ursula
A1 - Dziobek, Isabel
T1 - From face to face
BT - the contribution of facial mimicry to cognitive and emotional empathy
JF - Cognition and Emotion
N2 - Despite advances in the conceptualisation of facial mimicry, its role in the processing of social information is a matter of debate. In the present study, we investigated the relationship between mimicry and cognitive and emotional empathy. To assess mimicry, facial electromyography was recorded for 70 participants while they completed the Multifaceted Empathy Test, which presents complex context-embedded emotional expressions. As predicted, inter-individual differences in emotional and cognitive empathy were associated with the level of facial mimicry. For positive emotions, the intensity of the mimicry response scaled with the level of state emotional empathy. Mimicry was stronger for the emotional empathy task compared to the cognitive empathy task. The specific empathy condition could be successfully detected from facial muscle activity at the level of single individuals using machine learning techniques. These results support the view that mimicry occurs depending on the social context as a tool to affiliate and it is involved in cognitive as well as emotional empathy.
KW - Facial mimicry
KW - empathy
KW - emotional
KW - cognitive
KW - complex emotions
Y1 - 2019
U6 - https://doi.org/10.1080/02699931.2019.1596068
SN - 0269-9931
SN - 1464-0600
VL - 33
IS - 8
SP - 1672
EP - 1686
PB - Routledge, Taylor & Francis Group
CY - Abingdon
ER -
TY - JOUR
A1 - Döllner, Jürgen Roland Friedrich
T1 - Geospatial artificial intelligence
BT - potentials of machine learning for 3D point clouds and geospatial digital twins
JF - Journal of photogrammetry, remote sensing and geoinformation science : PFG : Photogrammetrie, Fernerkundung, Geoinformation
N2 - Artificial intelligence (AI) is changing fundamentally the way how IT solutions are implemented and operated across all application domains, including the geospatial domain. This contribution outlines AI-based techniques for 3D point clouds and geospatial digital twins as generic components of geospatial AI. First, we briefly reflect on the term "AI" and outline technology developments needed to apply AI to IT solutions, seen from a software engineering perspective. Next, we characterize 3D point clouds as key category of geodata and their role for creating the basis for geospatial digital twins; we explain the feasibility of machine learning (ML) and deep learning (DL) approaches for 3D point clouds. In particular, we argue that 3D point clouds can be seen as a corpus with similar properties as natural language corpora and formulate a "Naturalness Hypothesis" for 3D point clouds. In the main part, we introduce a workflow for interpreting 3D point clouds based on ML/DL approaches that derive domain-specific and application-specific semantics for 3D point clouds without having to create explicit spatial 3D models or explicit rule sets. Finally, examples are shown how ML/DL enables us to efficiently build and maintain base data for geospatial digital twins such as virtual 3D city models, indoor models, or building information models.
N2 - Georäumliche Künstliche Intelligenz: Potentiale des Maschinellen Lernens für 3D-Punktwolken und georäumliche digitale Zwillinge. Künstliche Intelligenz (KI) verändert grundlegend die Art und Weise, wie IT-Lösungen in allen Anwendungsbereichen, einschließlich dem Geoinformationsbereich, implementiert und betrieben werden. In diesem Beitrag stellen wir KI-basierte Techniken für 3D-Punktwolken als einen Baustein der georäumlichen KI vor. Zunächst werden kurz der Begriff "KI” und die technologischen Entwicklungen skizziert, die für die Anwendung von KI auf IT-Lösungen aus der Sicht der Softwaretechnik erforderlich sind. Als nächstes charakterisieren wir 3D-Punktwolken als Schlüsselkategorie von Geodaten und ihre Rolle für den Aufbau von räumlichen digitalen Zwillingen; wir erläutern die Machbarkeit der Ansätze für Maschinelles Lernen (ML) und Deep Learning (DL) in Bezug auf 3D-Punktwolken. Insbesondere argumentieren wir, dass 3D-Punktwolken als Korpus mit ähnlichen Eigenschaften wie natürlichsprachliche Korpusse gesehen werden können und
formulieren eine "Natürlichkeitshypothese” für 3D-Punktwolken. Im Hauptteil stellen wir einen Workflow zur Interpretation von 3D-Punktwolken auf der Grundlage von ML/DL-Ansätzen vor, die eine domänenspezifische und anwendungsspezifische Semantik für 3D-Punktwolken ableiten, ohne explizite räumliche 3D-Modelle oder explizite Regelsätze erstellen zu müssen. Abschließend wird an Beispielen gezeigt, wie ML/DL es ermöglichen, Basisdaten für räumliche digitale Zwillinge, wie z.B. für virtuelle 3D-Stadtmodelle, Innenraummodelle oder Gebäudeinformationsmodelle, effizient aufzubauen und zu pflegen.
KW - geospatial artificial intelligence
KW - machine learning
KW - deep learning
KW - 3D
KW - point clouds
KW - geospatial digital twins
KW - 3D city models
Y1 - 2020
U6 - https://doi.org/10.1007/s41064-020-00102-3
SN - 2512-2789
SN - 2512-2819
VL - 88
IS - 1
SP - 15
EP - 24
PB - Springer International Publishing
CY - Cham
ER -
TY - JOUR
A1 - Ehrig, Hartmut
A1 - Golas, Ulrike
A1 - Habel, Annegret
A1 - Lambers, Leen
A1 - Orejas, Fernando
T1 - M-Adhesive Transformation Systems with Nested Application Conditions Part 2: Embedding, Critical Pairs and Local Confluence
JF - Fundamenta informaticae
N2 - Graph transformation systems have been studied extensively and applied to several areas of computer science like formal language theory, the modeling of databases, concurrent or distributed systems, and visual, logical, and functional programming. In most kinds of applications it is necessary to have the possibility of restricting the applicability of rules. This is usually done by means of application conditions. In this paper, we continue the work of extending the fundamental theory of graph transformation to the case where rules may use arbitrary (nested) application conditions. More precisely, we generalize the Embedding theorem, and we study how local confluence can be checked in this context. In particular, we define a new notion of critical pair which allows us to formulate and prove a Local Confluence Theorem for the general case of rules with nested application conditions. All our results are presented, not for a specific class of graphs, but for any arbitrary M-adhesive category, which means that our results apply to most kinds of graphical structures. We demonstrate our theory on the modeling of an elevator control by a typed graph transformation system with positive and negative application conditions.
KW - M-adhesive transformation systems
KW - M-adhesive categories
KW - graph replacement categories
KW - nested application conditions
KW - embedding
KW - critical pairs
KW - local confluence
Y1 - 2012
U6 - https://doi.org/10.3233/FI-2012-705
SN - 0169-2968
VL - 118
IS - 1-2
SP - 35
EP - 63
PB - IOS Press
CY - Amsterdam
ER -
TY - JOUR
A1 - Ehrig, Hartmut
A1 - Golas, Ulrike
A1 - Habel, Annegret
A1 - Lambers, Leen
A1 - Orejas, Fernando
T1 - M-adhesive transformation systems with nested application conditions. Part 1: parallelism, concurrency and amalgamation
JF - Mathematical structures in computer science : a journal in the applications of categorical, algebraic and geometric methods in computer science
N2 - Nested application conditions generalise the well-known negative application conditions and are important for several application domains. In this paper, we present Local Church-Rosser, Parallelism, Concurrency and Amalgamation Theorems for rules with nested application conditions in the framework of M-adhesive categories, where M-adhesive categories are slightly more general than weak adhesive high-level replacement categories. Most of the proofs are based on the corresponding statements for rules without application conditions and two shift lemmas stating that nested application conditions can be shifted over morphisms and rules.
Y1 - 2014
U6 - https://doi.org/10.1017/S0960129512000357
SN - 0960-1295
SN - 1469-8072
VL - 24
IS - 4
PB - Cambridge Univ. Press
CY - New York
ER -
TY - JOUR
A1 - Felgentreff, Tim
A1 - Perscheid, Michael
A1 - Hirschfeld, Robert
T1 - Implementing record and refinement for debugging timing-dependent communication
JF - Science of computer programming
N2 - Distributed applications are hard to debug because timing-dependent network communication is a source of non-deterministic behavior. Current approaches to debug non deterministic failures include post-mortem debugging as well as record and replay. However, the first impairs system performance to gather data, whereas the latter requires developers to understand the timing-dependent communication at a lower level of abstraction than they develop at. Furthermore, both approaches require intrusive core library modifications to gather data from live systems. In this paper, we present the Peek-At-Talk debugger for investigating non-deterministic failures with low overhead in a systematic, top-down method, with a particular focus on tool-building issues in the following areas: First, we show how our debugging framework Path Tools guides developers from failures to their root causes and gathers run-time data with low overhead. Second, we present Peek-At-Talk, an extension to our Path Tools framework to record non-deterministic communication and refine behavioral data that connects source code with network events. Finally, we scope changes to the core library to record network communication without impacting other network applications.
KW - Distributed debugging
KW - Record and replay
KW - Dynamic analysis
KW - Record and refinement
Y1 - 2016
U6 - https://doi.org/10.1016/j.scico.2015.11.006
SN - 0167-6423
SN - 1872-7964
VL - 134
SP - 4
EP - 18
PB - Elsevier
CY - Amsterdam
ER -
TY - INPR
A1 - Fish, Andrew
A1 - Lambers, Leen
T1 - Special issue on graph transformation and visual modeling techniques - guest editors' introduction
T2 - Journal of visual languages and computing
Y1 - 2013
U6 - https://doi.org/10.1016/j.jvlc.2013.08.004
SN - 1045-926X
SN - 1095-8533
VL - 24
IS - 6
SP - 419
EP - 420
PB - Elsevier
CY - London
ER -
TY - GEN
A1 - Florio, Alessandro
A1 - Trapp, Matthias
A1 - Döllner, Jürgen Roland Friedrich
T1 - Semantic-driven Visualization Techniques for Interactive Exploration of 3D Indoor Models
T2 - 2019 23rd International Conference Information Visualisation (IV)
N2 - The availability of detailed virtual 3D building models including representations of indoor elements, allows for a wide number of applications requiring effective exploration and navigation functionality. Depending on the application context, users should be enabled to focus on specific Objects-of-Interests (OOIs) or important building elements. This requires approaches to filtering building parts as well as techniques to visualize important building objects and their relations. For it, this paper explores the application and combination of interactive rendering techniques as well as their semanticallydriven configuration in the context of 3D indoor models.
KW - Building Information Models
KW - BIM
KW - Industry Foundation Classes
KW - IFC
KW - Interactive Visualization
KW - Real-time Rendering
Y1 - 2019
SN - 978-1-7281-2838-2
SN - 978-1-7281-2839-9
U6 - https://doi.org/10.1109/IV.2019.00014
SN - 2375-0138
SN - 1550-6037
SP - 25
EP - 30
PB - Inst. of Electr. and Electronics Engineers
CY - Los Alamitos
ER -
TY - JOUR
A1 - Freudenberg, Bert
A1 - Ingalls, Dan
A1 - Felgentreff, Tim
A1 - Pape, Tobias
A1 - Hirschfeld, Robert
T1 - SqueakJS A Modern and Practical Smalltalk that Runs in Any Browser
JF - ACM SIGPLAN notices
N2 - We report our experience in implementing SqueakJS, a bitcompatible implementation of Squeak/Smalltalk written in pure JavaScript. SqueakJS runs entirely in theWeb browser with a virtual file system that can be directed to a server or client-side storage. Our implementation is notable for simplicity and performance gained through adaptation to the host object memory and deployment leverage gained through the Lively Web development environment. We present several novel techniques as well as performance measurements for the resulting virtual machine. Much of this experience is potentially relevant to preserving other dynamic language systems and making them available in a browser-based environment.
KW - Smalltalk
KW - Squeak
KW - Web browsers
KW - JavaScript
Y1 - 2015
U6 - https://doi.org/10.1145/10.1145/2661088.2661100
SN - 0362-1340
SN - 1558-1160
VL - 50
IS - 2
SP - 57
EP - 66
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Friedrich, Tobias
A1 - Katzmann, Maximilian
A1 - Krohmer, Anton
T1 - Unbounded Discrepancy of Deterministic Random Walks on Grids
JF - SIAM journal on discrete mathematics
N2 - Random walks are frequently used in randomized algorithms. We study a derandomized variant of a random walk on graphs called the rotor-router model. In this model, instead of distributing tokens randomly, each vertex serves its neighbors in a fixed deterministic order. For most setups, both processes behave in a remarkably similar way: Starting with the same initial configuration, the number of tokens in the rotor-router model deviates only slightly from the expected number of tokens on the corresponding vertex in the random walk model. The maximal difference over all vertices and all times is called single vertex discrepancy. Cooper and Spencer [Combin. Probab. Comput., 15 (2006), pp. 815-822] showed that on Z(d), the single vertex discrepancy is only a constant c(d). Other authors also determined the precise value of c(d) for d = 1, 2. All of these results, however, assume that initially all tokens are only placed on one partition of the bipartite graph Z(d). We show that this assumption is crucial by proving that, otherwise, the single vertex discrepancy can become arbitrarily large. For all dimensions d >= 1 and arbitrary discrepancies l >= 0, we construct configurations that reach a discrepancy of at least l.
KW - deterministic random walk
KW - rotor-router model
KW - single vertex discrepancy
Y1 - 2018
U6 - https://doi.org/10.1137/17M1131088
SN - 0895-4801
SN - 1095-7146
VL - 32
IS - 4
SP - 2441
EP - 2452
PB - Society for Industrial and Applied Mathematics
CY - Philadelphia
ER -
TY - GEN
A1 - Gawron, Marian
A1 - Cheng, Feng
A1 - Meinel, Christoph
T1 - PVD: Passive Vulnerability Detection
T2 - 8th International Conference on Information and Communication Systems (ICICS)
N2 - The identification of vulnerabilities relies on detailed information about the target infrastructure. The gathering of the necessary information is a crucial step that requires an intensive scanning or mature expertise and knowledge about the system even though the information was already available in a different context. In this paper we propose a new method to detect vulnerabilities that reuses the existing information and eliminates the necessity of a comprehensive scan of the target system. Since our approach is able to identify vulnerabilities without the additional effort of a scan, we are able to increase the overall performance of the detection. Because of the reuse and the removal of the active testing procedures, our approach could be classified as a passive vulnerability detection. We will explain the approach and illustrate the additional possibility to increase the security awareness of users. Therefore, we applied the approach on an experimental setup and extracted security relevant information from web logs.
Y1 - 2017
SN - 978-1-5090-4243-2
U6 - https://doi.org/10.1109/IACS.2017.7921992
SN - 2471-125X
SP - 322
EP - 327
PB - IEEE
CY - New York
ER -
TY - JOUR
A1 - Gebser, Martin
A1 - Obermeier, Philipp
A1 - Otto, Thomas
A1 - Schaub, Torsten H.
A1 - Sabuncu, Orkunt
A1 - Van Nguyen,
A1 - Tran Cao Son,
T1 - Experimenting with robotic intra-logistics domains
JF - Theory and practice of logic programming
N2 - We introduce the asprilo1 framework to facilitate experimental studies of approaches addressing complex dynamic applications. For this purpose, we have chosen the domain of robotic intra-logistics. This domain is not only highly relevant in the context of today's fourth industrial revolution but it moreover combines a multitude of challenging issues within a single uniform framework. This includes multi-agent planning, reasoning about action, change, resources, strategies, etc. In return, asprilo allows users to study alternative solutions as regards effectiveness and scalability. Although asprilo relies on Answer Set Programming and Python, it is readily usable by any system complying with its fact-oriented interface format. This makes it attractive for benchmarking and teaching well beyond logic programming. More precisely, asprilo consists of a versatile benchmark generator, solution checker and visualizer as well as a bunch of reference encodings featuring various ASP techniques. Importantly, the visualizer's animation capabilities are indispensable for complex scenarios like intra-logistics in order to inspect valid as well as invalid solution candidates. Also, it allows for graphically editing benchmark layouts that can be used as a basis for generating benchmark suites.
Y1 - 2018
U6 - https://doi.org/10.1017/S1471068418000200
SN - 1471-0684
SN - 1475-3081
VL - 18
IS - 3-4
SP - 502
EP - 519
PB - Cambridge Univ. Press
CY - New York
ER -
TY - JOUR
A1 - Gevay, Gabor E.
A1 - Rabl, Tilmann
A1 - Bress, Sebastian
A1 - Maclai-Tahy, Lorand
A1 - Quiane-Ruiz, Jorge-Arnulfo
A1 - Markl, Volker
T1 - Imperative or Functional Control Flow Handling: Why not the Best of Both Worlds?
JF - SIGMOD record
N2 - Modern data analysis tasks often involve control flow statements, such as the iterations in PageRank and K-means. To achieve scalability, developers usually implement these tasks in distributed dataflow systems, such as Spark and Flink. Designers of such systems have to choose between providing imperative or functional control flow constructs to users. Imperative constructs are easier to use, but functional constructs are easier to compile to an efficient dataflow job. We propose Mitos, a system where control flow is both easy to use and efficient. Mitos relies on an intermediate representation based on the static single assignment form. This allows us to abstract away from specific control flow constructs and treat any imperative control flow uniformly both when building the dataflow job and when coordinating the distributed execution.
Y1 - 2022
U6 - https://doi.org/10.1109/ICDE51399.2021.00127
SN - 0163-5808
SN - 1943-5835
VL - 51
IS - 1
SP - 60
EP - 67
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Ghahremani, Sona
A1 - Giese, Holger
T1 - Evaluation of self-healing systems
BT - An analysis of the state-of-the-art and required improvements
JF - Computers
N2 - Evaluating the performance of self-adaptive systems is challenging due to their interactions with often highly dynamic environments. In the specific case of self-healing systems, the performance evaluations of self-healing approaches and their parameter tuning rely on the considered characteristics of failure occurrences and the resulting interactions with the self-healing actions. In this paper, we first study the state-of-the-art for evaluating the performances of self-healing systems by means of a systematic literature review. We provide a classification of different input types for such systems and analyse the limitations of each input type. A main finding is that the employed inputs are often not sophisticated regarding the considered characteristics for failure occurrences. To further study the impact of the identified limitations, we present experiments demonstrating that wrong assumptions regarding the characteristics of the failure occurrences can result in large performance prediction errors, disadvantageous design-time decisions concerning the selection of alternative self-healing approaches, and disadvantageous deployment-time decisions concerning parameter tuning. Furthermore, the experiments indicate that employing multiple alternative input characteristics can help with reducing the risk of premature disadvantageous design-time decisions.
KW - self-healing
KW - failure model
KW - performance
KW - simulation
KW - evaluation
Y1 - 2020
U6 - https://doi.org/10.3390/computers9010016
SN - 2073-431X
VL - 9
IS - 1
PB - MDPI
CY - Basel
ER -
TY - GEN
A1 - Ghahremani, Sona
A1 - Giese, Holger
T1 - Performance evaluation for self-healing systems
BT - Current Practice & Open Issues
T2 - 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)
N2 - Evaluating the performance of self-adaptive systems (SAS) is challenging due to their complexity and interaction with the often highly dynamic environment. In the context of self-healing systems (SHS), employing simulators has been shown to be the most dominant means for performance evaluation. Simulating a SHS also requires realistic fault injection scenarios. We study the state of the practice for evaluating the performance of SHS by means of a systematic literature review. We present the current practice and point out that a more thorough and careful treatment in evaluating the performance of SHS is required.
KW - self-healing
KW - failure profile
KW - evaluation
KW - simulator
KW - performance
Y1 - 2019
SN - 978-1-7281-2406-3
U6 - https://doi.org/10.1109/FAS-W.2019.00039
SP - 116
EP - 119
PB - IEEE
CY - New York
ER -
TY - JOUR
A1 - Ghahremani, Sona
A1 - Giese, Holger
A1 - Vogel, Thomas
T1 - Improving scalability and reward of utility-driven self-healing for large dynamic architectures
JF - ACM transactions on autonomous and adaptive systems
N2 - Self-adaptation can be realized in various ways. Rule-based approaches prescribe the adaptation to be executed if the system or environment satisfies certain conditions. They result in scalable solutions but often with merely satisfying adaptation decisions. In contrast, utility-driven approaches determine optimal decisions by using an often costly optimization, which typically does not scale for large problems. We propose a rule-based and utility-driven adaptation scheme that achieves the benefits of both directions such that the adaptation decisions are optimal, whereas the computation scales by avoiding an expensive optimization. We use this adaptation scheme for architecture-based self-healing of large software systems. For this purpose, we define the utility for large dynamic architectures of such systems based on patterns that define issues the self-healing must address. Moreover, we use pattern-based adaptation rules to resolve these issues. Using a pattern-based scheme to define the utility and adaptation rules allows us to compute the impact of each rule application on the overall utility and to realize an incremental and efficient utility-driven self-healing. In addition to formally analyzing the computational effort and optimality of the proposed scheme, we thoroughly demonstrate its scalability and optimality in terms of reward in comparative experiments with a static rule-based approach as a baseline and a utility-driven approach using a constraint solver. These experiments are based on different failure profiles derived from real-world failure logs. We also investigate the impact of different failure profile characteristics on the scalability and reward to evaluate the robustness of the different approaches.
KW - self-healing
KW - adaptation rules
KW - architecture-based adaptation
KW - utility
KW - reward
KW - scalability
KW - performance
KW - failure profile model
Y1 - 2020
U6 - https://doi.org/10.1145/3380965
SN - 1556-4665
SN - 1556-4703
VL - 14
IS - 3
PB - Association for Computing Machinery
CY - New York
ER -
TY - GEN
A1 - Giese, Holger
ED - Kouchnarenko, Olga
ED - Khosravi, Ramtin
T1 - Formal models and analysis for self-adaptive cyber-physical systems
BT - (extended abstract)
T2 - Lecture notes in computer science
N2 - In this extended abstract, we will analyze the current challenges for the envisioned Self-Adaptive CPS. In addition, we will outline our results to approach these challenges with SMARTSOS [10] a generic approach based on extensions of graph transformation systems employing open and adaptive collaborations and models at runtime for trustworthy self-adaptation, self-organization, and evolution of the individual systems and the system-of-systems level taking the independent development, operation, management, and evolution of these systems into account.
Y1 - 2017
SN - 978-3-319-57666-4
SN - 978-3-319-57665-7
U6 - https://doi.org/10.1007/978-3-319-57666-4_1
SN - 0302-9743
SN - 1611-3349
VL - 10231
SP - 3
EP - 9
PB - Springer
CY - Cham
ER -
TY - GEN
A1 - Giese, Holger Burkhard
T1 - Software Engineering for Smart Cyber-Physical Systems
BT - Challenges and Opportunities
T2 - Proceedings of the 12th Innovations on Software Engineering Conference
N2 - Currently, a transformation of our technical world into a networked technical world where besides the embedded systems with their interaction with the physical world the interconnection of these nodes in the cyber world becomes a reality can be observed. In parallel nowadays there is a strong trend to employ artificial intelligence techniques and in particular machine learning to make software behave smart. Often cyber-physical systems must be self-adaptive at the level of the individual systems to operate as elements in open, dynamic, and deviating overall structures and to adapt to open and dynamic contexts while being developed, operated, evolved, and governed independently.
In this presentation, we will first discuss the envisioned future scenarios for cyber-physical systems with an emphasis on the synergies networking can offer and then characterize which challenges for the design, production, and operation of these systems result. We will then discuss to what extent our current capabilities, in particular concerning software engineering match these challenges and where substantial improvements for the software engineering are crucial. In today's software engineering for embedded systems models are used to plan systems upfront to maximize envisioned properties on the one hand and minimize cost on the other hand. When applying the same ideas to software for smart cyber-physical systems, it soon turned out that for these systems often somehow more subtle links between the involved models and the requirements, users, and environment exist. Self-adaptation and runtime models have been advocated as concepts to covers the demands that result from these subtler links. Lately, both trends have been brought together more thoroughly by the notion of self-aware computing systems. We will review the underlying causes, discuss some our work in this direction, and outline related open challenges and potential for future approaches to software engineering for smart cyber-physical systems.
KW - Software Engineering
KW - Cyber-Physical Systems
KW - Self-aware computing systems
Y1 - 2019
SN - 978-1-4503-6215-3
U6 - https://doi.org/10.1145/3299771.3301650
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Giese, Holger
A1 - Wagner, Robert
T1 - From model transformation to incremental bidirectional model synchronization
N2 - The model-driven software development paradigm requires that appropriate model transformations are applicable in different stages of the development process. The transformations have to consistently propagate changes between the different involved models and thus ensure a proper model synchronization. However, most approaches today do not fully support the requirements for model synchronization and focus only on classical one-way batch-oriented transformations. In this paper, we present our approach for an incremental model transformation which supports model synchronization. Our approach employs the visual, formal, and bidirectional transformation technique of triple graph grammars. Using this declarative specification formalism, we focus on the efficient execution of the transformation rules and how to achieve an incremental model transformation for synchronization purposes. We present an evaluation of our approach and demonstrate that due to the speedup for the incremental processing in the average case even larger models can be tackled.
Y1 - 2009
UR - http://www.springerlink.com/content/109378
U6 - https://doi.org/10.1007/s10270-008-0089-9
SN - 1619-1366
ER -
TY - JOUR
A1 - Glander, Tassilo
A1 - Döllner, Jürgen Roland Friedrich
T1 - Abstract representations for interactive visualization of virtual 3D city models
N2 - Virtual 3D city models increasingly cover whole city areas; hence, the perception of complex urban structures becomes increasingly difficult. Using abstract visualization, complexity of these models can be hidden where its visibility is unnecessary, while important features are maintained and highlighted for better comprehension and communication. We present a technique to automatically generalize a given virtual 3D city model consisting of building models, an infrastructure network and optional land coverage data; this technique creates several representations of increasing levels of abstraction. Using the infrastructure network, our technique groups building models and replaces them with cell blocks, while preserving local landmarks. By computing a landmark hierarchy, we reduce the set of initial landmarks in a spatially balanced manner for use in higher levels of abstraction. In four application examples, we demonstrate smooth visualization of transitions between precomputed representations; dynamic landmark highlighting according to virtual camera distance; an implementation of a cognitively enhanced route representation, and generalization lenses to combine precomputed representations in focus + context visualization.
Y1 - 2009
UR - http://www.sciencedirect.com/science/journal/01989715
U6 - https://doi.org/10.1016/j.compenvurbsys.2009.07.003
SN - 0198-9715
ER -
TY - CHAP
A1 - Grüner, Andreas
A1 - Mühle, Alexander
A1 - Gayvoronskaya, Tatiana
A1 - Meinel, Christoph
T1 - A quantifiable trustmModel for Blockchain-based identity management
T2 - IEEE 2018 International Congress on Cybermatics / 2018 IEEE Conferences on Internet of Things, Green Computing and Communications, cyber, physical and Social Computing, Smart Data, Blockchain, Computer and Information Technology
KW - Blockchain
KW - distributed ledger technology
KW - digital identity
KW - self-sovereign identity
KW - trust
KW - identity management
Y1 - 2019
SN - 978-1-5386-7975-3
U6 - https://doi.org/10.1109/Cybermatics_2018.2018.00250
SP - 1475
EP - 1482
PB - IEEE
CY - New York
ER -
TY - JOUR
A1 - Grüner, Andreas
A1 - Mühle, Alexander
A1 - Meinel, Christoph
T1 - ATIB
BT - Design and evaluation of an architecture for brokered self-sovereign identity integration and trust-enhancing attribute aggregation for service provider
JF - IEEE access : practical research, open solutions / Institute of Electrical and Electronics Engineers
N2 - Identity management is a principle component of securing online services. In the advancement of traditional identity management patterns, the identity provider remained a Trusted Third Party (TTP). The service provider and the user need to trust a particular identity provider for correct attributes amongst other demands. This paradigm changed with the invention of blockchain-based Self-Sovereign Identity (SSI) solutions that primarily focus on the users. SSI reduces the functional scope of the identity provider to an attribute provider while enabling attribute aggregation. Besides that, the development of new protocols, disregarding established protocols and a significantly fragmented landscape of SSI solutions pose considerable challenges for an adoption by service providers. We propose an Attribute Trust-enhancing Identity Broker (ATIB) to leverage the potential of SSI for trust-enhancing attribute aggregation. Furthermore, ATIB abstracts from a dedicated SSI solution and offers standard protocols. Therefore, it facilitates the adoption by service providers. Despite the brokered integration approach, we show that ATIB provides a high security posture. Additionally, ATIB does not compromise the ten foundational SSI principles for the users.
KW - Blockchains
KW - Protocols
KW - Authentication
KW - Licenses
KW - Security
KW - Privacy
KW - Identity management systems
KW - Attribute aggregation
KW - attribute assurance
KW - digital identity
KW - identity broker
KW - self-sovereign identity
KW - trust model
Y1 - 2021
U6 - https://doi.org/10.1109/ACCESS.2021.3116095
SN - 2169-3536
VL - 9
SP - 138553
EP - 138570
PB - Institute of Electrical and Electronics Engineers
CY - New York, NY
ER -
TY - JOUR
A1 - Gévay, Gábor E.
A1 - Rabl, Tilmann
A1 - Breß, Sebastian
A1 - Madai-Tahy, Loránd
A1 - Quiané-Ruiz, Jorge-Arnulfo
A1 - Markl, Volker
T1 - Imperative or functional control flow handling
BT - why not the best of both worlds?
JF - SIGMOD record / Association for Computing Machinery, Special Interest Group on Management of Data
N2 - Modern data analysis tasks often involve control flow statements, such as the iterations in PageRank and K-means. To achieve scalability, developers usually implement these tasks in distributed dataflow systems, such as Spark and Flink. Designers of such systems have to choose between providing imperative or functional control flow constructs to users. Imperative constructs are easier to use, but functional constructs are easier to compile to an efficient dataflow job. We propose Mitos, a system where control flow is both easy to use and efficient. Mitos relies on an intermediate representation based on the static single assignment form. This allows us to abstract away from specific control flow constructs and treat any imperative control flow uniformly both when building the dataflow job and when coordinating the distributed execution.
Y1 - 2022
U6 - https://doi.org/10.1145/3542700.3542715
SN - 0163-5808
VL - 51
IS - 1
SP - 60
EP - 67
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Göbel, Andreas
A1 - Lagodzinski, Gregor J. A.
A1 - Seidel, Karen
T1 - Counting homomorphisms to trees modulo a prime
JF - ACM transactions on computation theory : TOCT / Association for Computing Machinery
N2 - Many important graph-theoretic notions can be encoded as counting graph homomorphism problems, such as partition functions in statistical physics, in particular independent sets and colourings. In this article, we study the complexity of #(p) HOMSTOH, the problem of counting graph homomorphisms from an input graph to a graph H modulo a prime number p. Dyer and Greenhill proved a dichotomy stating that the tractability of non-modular counting graph homomorphisms depends on the structure of the target graph. Many intractable cases in non-modular counting become tractable in modular counting due to the common phenomenon of cancellation. In subsequent studies on counting modulo 2, however, the influence of the structure of H on the tractability was shown to persist, which yields similar dichotomies.
Our main result states that for every tree H and every prime p the problem #pHOMSTOH is either polynomial time computable or #P-p-complete. This relates to the conjecture of Faben and Jerrum stating that this dichotomy holds for every graph H when counting modulo 2. In contrast to previous results on modular counting, the tractable cases of #pHOMSTOH are essentially the same for all values of the modulo when H is a tree. To prove this result, we study the structural properties of a homomorphism. As an important interim result, our study yields a dichotomy for the problem of counting weighted independent sets in a bipartite graph modulo some prime p. These results are the first suggesting that such dichotomies hold not only for the modulo 2 case but also for the modular counting functions of all primes p.
KW - Graph homomorphisms
KW - modular counting
KW - complexity dichotomy
Y1 - 2021
U6 - https://doi.org/10.1145/3460958
SN - 1942-3454
SN - 1942-3462
VL - 13
IS - 3
SP - 1
EP - 33
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Haarmann, Stephan
A1 - Holfter, Adrian
A1 - Pufahl, Luise
A1 - Weske, Mathias
T1 - Formal framework for checking compliance of data-driven case management
JF - Journal on data semantics : JoDS
N2 - Business processes are often specified in descriptive or normative models. Both types of models should adhere to internal and external regulations, such as company guidelines or laws. Employing compliance checking techniques, it is possible to verify process models against rules. While traditionally compliance checking focuses on well-structured processes, we address case management scenarios. In case management, knowledge workers drive multi-variant and adaptive processes. Our contribution is based on the fragment-based case management approach, which splits a process into a set of fragments. The fragments are synchronized through shared data but can, otherwise, be dynamically instantiated and executed. We formalize case models using Petri nets. We demonstrate the formalization for design-time and run-time compliance checking and present a proof-of-concept implementation. The application of the implemented compliance checking approach to a use case exemplifies its effectiveness while designing a case model. The empirical evaluation on a set of case models for measuring the performance of the approach shows that rules can often be checked in less than a second.
KW - Compliance checking
KW - Case management
KW - Model verification
KW - Data-centric
KW - processes
Y1 - 2021
U6 - https://doi.org/10.1007/s13740-021-00120-3
SN - 1861-2032
SN - 1861-2040
VL - 10
IS - 1-2
SP - 143
EP - 163
PB - Springer
CY - Heidelberg
ER -
TY - JOUR
A1 - Hacker, Philipp
A1 - Krestel, Ralf
A1 - Grundmann, Stefan
A1 - Naumann, Felix
T1 - Explainable AI under contract and tort law
BT - legal incentives and technical challenges
JF - Artificial intelligence and law
N2 - This paper shows that the law, in subtle ways, may set hitherto unrecognized incentives for the adoption of explainable machine learning applications. In doing so, we make two novel contributions. First, on the legal side, we show that to avoid liability, professional actors, such as doctors and managers, may soon be legally compelled to use explainable ML models. We argue that the importance of explainability reaches far beyond data protection law, and crucially influences questions of contractual and tort liability for the use of ML models. To this effect, we conduct two legal case studies, in medical and corporate merger applications of ML. As a second contribution, we discuss the (legally required) trade-off between accuracy and explainability and demonstrate the effect in a technical case study in the context of spam classification.
KW - explainability
KW - explainable AI
KW - interpretable machine learning
KW - contract
KW - law
KW - tort law
KW - explainability-accuracy trade-off
KW - medical malpractice
KW - corporate takeovers
Y1 - 2020
U6 - https://doi.org/10.1007/s10506-020-09260-6
SN - 0924-8463
SN - 1572-8382
VL - 28
IS - 4
SP - 415
EP - 439
PB - Springer
CY - Dordrecht
ER -
TY - JOUR
A1 - Hameed, Mazhar
A1 - Naumann, Felix
T1 - Data Preparation
BT - a survey of commercial tools
JF - SIGMOD record
N2 - Raw data are often messy: they follow different encodings, records are not well structured, values do not adhere to patterns, etc. Such data are in general not fit to be ingested by downstream applications, such as data analytics tools, or even by data management systems. The act of obtaining information from raw data relies on some data preparation process. Data preparation is integral to advanced data analysis and data management, not only for data science but for any data-driven applications. Existing data preparation tools are operational and useful, but there is still room for improvement and optimization. With increasing data volume and its messy nature, the demand for prepared data increases day by day.
To cater to this demand, companies and researchers are developing techniques and tools for data preparation. To better understand the available data preparation systems, we have conducted a survey to investigate (1) prominent data preparation tools, (2) distinctive tool features, (3) the need for preliminary data processing even for these tools and, (4) features and abilities that are still lacking. We conclude with an argument in support of automatic and intelligent data preparation beyond traditional and simplistic techniques.
KW - data quality
KW - data cleaning
KW - data wrangling
Y1 - 2020
U6 - https://doi.org/10.1145/3444831.3444835
SN - 0163-5808
SN - 1943-5835
VL - 49
IS - 3
SP - 18
EP - 29
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Hartig, Olaf
A1 - Pirrò, Giuseppe
T1 - SPARQL with property paths on the Web
JF - Semantic web
N2 - Linked Data on the Web represents an immense source of knowledge suitable to be automatically processed and queried. In this respect, there are different approaches for Linked Data querying that differ on the degree of centralization adopted. On one hand, the SPARQL query language, originally defined for querying single datasets, has been enhanced with features to query federations of datasets; however, this attempt is not sufficient to cope with the distributed nature of data sources available as Linked Data. On the other hand, extensions or variations of SPARQL aim to find trade-offs between centralized and fully distributed querying. The idea is to partially move the computational load from the servers to the clients. Despite the variety and the relative merits of these approaches, as of today, there is no standard language for querying Linked Data on theWeb. A specific requirement for such a language to capture the distributed, graph-like nature of Linked Data sources on the Web is a support of graph navigation. Recently, SPARQL has been extended with a navigational feature called property paths (PPs). However, the semantics of SPARQL restricts the scope of navigation via PPs to single RDF graphs. This restriction limits the applicability of PPs for querying distributed Linked Data sources on the Web. To fill this gap, in this paper we provide formal foundations for evaluating PPs on the Web, thus contributing to the definition of a query language for Linked Data. We first introduce a family of reachability-based query semantics for PPs that distinguish between navigation on the Web and navigation at the data level. Thereafter, we consider another, alternative query semantics that couples Web graph navigation and data level navigation; we call it context-based semantics. Given these semantics, we find that for some PP-based SPARQL queries a complete evaluation on the Web is not possible. To study this phenomenon we introduce a notion of Web-safeness of queries, and prove a decidable syntactic property that enables systems to identify queries that areWeb-safe. In addition to establishing these formal foundations, we conducted an experimental comparison of the context-based semantics and a reachability- based semantics. Our experiments show that when evaluating a PP-based query under the context-based semantics one experiences a significantly smaller number of dereferencing operations, but the computed query result may contain less solutions.
KW - Property paths
KW - Web navigational language
KW - Web safeness
KW - SPARQL
Y1 - 2017
U6 - https://doi.org/10.3233/SW-160237
SN - 1570-0844
SN - 2210-4968
VL - 8
IS - 6
SP - 773
EP - 795
PB - IOS Press
CY - Amsterdam
ER -
TY - JOUR
A1 - Haupt, Michael
A1 - Adams, Bram
A1 - Timbermont, Stijn
A1 - Gibbs, Celina
A1 - Coady, Yvonne
A1 - Hirschfeld, Robert
T1 - Disentangling virtual machine architecture
N2 - Virtual machine (VM) implementations are made of intricately intertwined subsystems, interacting largely through implicit dependencies. As the degree of crosscutting present in VMs is very high, VM implementations exhibit significant internal complexity. This study proposes an architecture approach for VMs that regards a VM as a composite of service modules coordinated through explicit bidirectional interfaces. Aspect-oriented programming techniques are used to establish these interfaces, to coordinate module interaction, and to declaratively express concrete VM architectures. A VM architecture description language is presented in a case study, illustrating the application of the proposed architectural principles.
Y1 - 2009
UR - http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=4124007
U6 - https://doi.org/10.1049/iet-sen.2007.0121
SN - 1751-8806
ER -
TY - JOUR
A1 - Hehn, Jennifer
A1 - Mendez, Daniel
A1 - Uebernickel, Falk
A1 - Brenner, Walter
A1 - Broy, Manfred
T1 - On integrating design thinking for human-centered requirements engineering
JF - IEEE software
N2 - We elaborate on the possibilities and needs to integrate design thinking into requirements engineering, drawing from our research and project experiences. We suggest three approaches for tailoring and integrating design thinking and requirements engineering with complementary synergies and point at open challenges for research and practice.
KW - requirements engineering
KW - prototypes
KW - software
KW - electronic mail
KW - tools
KW - organizations
KW - design thinking
Y1 - 2019
U6 - https://doi.org/10.1109/MS.2019.2957715
SN - 0740-7459
SN - 1937-4194
VL - 37
IS - 2
SP - 25
EP - 31
PB - Inst. of Electr. and Electronics Engineers
CY - Los Alamitos
ER -
TY - JOUR
A1 - Henkenjohann, Richard
T1 - Role of individual motivations and privacy concerns in the adoption of German electronic patient record apps
BT - a mixed-methods study
JF - International journal of environmental research and public health : IJERPH / Molecular Diversity Preservation International
N2 - Germany's electronic patient record ("ePA") launched in 2021 with several attempts and years of delay. The development of such a large-scale project is a complex task, and so is its adoption. Individual attitudes towards an electronic health record are crucial, as individuals can reject opting-in to it and making any national efforts unachievable. Although the integration of an electronic health record serves potential benefits, it also constitutes risks for an individual's privacy. With a mixed-methods study design, this work provides evidence that different types of motivations and contextual privacy antecedents affect usage intentions towards the ePA. Most significantly, individual motivations stemming from feelings of volition or external mandates positively affect ePA adoption, although internal incentives are more powerful.
KW - personal electronic health records
KW - technology adoption
KW - endogenous
KW - motivations
KW - health information privacy concern
KW - mixed-methods
KW - ePA
Y1 - 2021
U6 - https://doi.org/10.3390/ijerph18189553
SN - 1660-4601
VL - 18
IS - 18
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Henkler, Stefan
A1 - Oberthuer, Simon
A1 - Giese, Holger
A1 - Seibel, Andreas
T1 - Model-driven runtime resource predictions for advanced mechatronic systems with dynamic data structures
JF - Computer systems science and engineering
N2 - The next generation of advanced mechatronic systems is expected to enhance their functionality and improve their performance by context-dependent behavior. Therefore, these systems require to represent information about their complex environment and changing sets of collaboration partners internally. This requirement is in contrast to the usually assumed static structures of embedded systems. In this paper, we present a model-driven approach which overcomes this situation by supporting dynamic data structures while still guaranteeing that valid worst-case execution times can be derived. It supports a flexible resource manager which avoids to operate with the prohibitive coarse worst-case boundaries but instead supports to run applications in different profiles which guarantee different resource requirements and put unused resources in a profile at other applications' disposal. By supporting the proper estimation of worst case execution time (WCET) and worst case number of iteration (WCNI) at runtime, we can further support to create new profiles, add or remove them at runtime in order to minimize the over-approximation of the resource consumption resulting from the dynamic data structures required for the outlined class of advanced systems.
KW - Model-Driven Engineering
KW - Safety Critical Systems
KW - Dynamic Data Structures
KW - Flexible Resource Manager
KW - Runtime WCET Analysis
Y1 - 2011
SN - 0267-6192
VL - 26
IS - 6
SP - 505
EP - 518
PB - IOP Publ. Ltd.
CY - Leicester
ER -
TY - GEN
A1 - Hernandez, Netzahualcoyotl
A1 - Demiray, Burcu
A1 - Arnrich, Bert
A1 - Favela, Jesus
T1 - An Exploratory Study to Detect Temporal Orientation Using Bluetooth's sensor
T2 - PervasiveHealth'19: Proceedings of the 13th EAI International Conference on Pervasive Computing Technologies for Healthcare
N2 - Mobile sensing technology allows us to investigate human behaviour on a daily basis. In the study, we examined temporal orientation, which refers to the capacity of thinking or talking about personal events in the past and future. We utilise the mksense platform that allows us to use the experience-sampling method. Individual's thoughts and their relationship with smartphone's Bluetooth data is analysed to understand in which contexts people are influenced by social environments, such as the people they spend the most time with. As an exploratory study, we analyse social condition influence through a collection of Bluetooth data and survey information from participant's smartphones. Preliminary results show that people are likely to focus on past events when interacting with close-related people, and focus on future planning when interacting with strangers. Similarly, people experience present temporal orientation when accompanied by known people. We believe that these findings are linked to emotions since, in its most basic state, emotion is a state of physiological arousal combined with an appropriated cognition. In this contribution, we envision a smartphone application for automatically inferring human emotions based on user's temporal orientation by using Bluetooth sensors, we briefly elaborate on the influential factor of temporal orientation episodes and conclude with a discussion and lessons learned.
KW - Mobile sensing
KW - Temporal orientation
KW - Social environment
KW - Human behaviour
KW - Bluetooth
Y1 - 2019
SN - 978-1-4503-6126-2
U6 - https://doi.org/10.1145/3329189.3329223
SN - 2153-1633
SP - 292
EP - 297
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Herzberg, Nico
A1 - Meyer, Andreas
A1 - Weske, Mathias
T1 - Improving business process intelligence by observing object state transitions
JF - Data & knowledge engineering
N2 - During the execution of business processes several events happen that are recorded in the company's information systems. These events deliver insights into process executions so that process monitoring and analysis can be performed resulting, for instance, in prediction of upcoming process steps or the analysis of the run time of single steps. While event capturing is trivial when a process engine with integrated logging capabilities is used, manual process execution environments do not provide automatic logging of events, so that typically external devices, like bar code scanners, have to be used. As experience shows, these manual steps are error-prone and induce additional work. Therefore, we use object state transitions as additional monitoring information, so-called object state transition events. Based on these object state transition events, we reason about the enablement and termination of activities and provide the basis for process monitoring and analysis in terms of a large event log. In this paper, we present the concept to utilize information from these object state transition events for capturing process progress. Furthermore, we discuss a methodology to create the required design time artifacts that then are used for monitoring at run time. In a proof-of-concept implementation, we show how the design time and run time side work and prove applicability of the introduced concept of object state transition events. (C) 2015 Elsevier B.V. All rights reserved.
KW - Business process management
KW - Events
KW - Data
KW - Process Monitoring
KW - BPMN
Y1 - 2015
U6 - https://doi.org/10.1016/j.datak.2015.07.008
SN - 0169-023X
SN - 1872-6933
VL - 98
SP - 144
EP - 164
PB - Elsevier
CY - Amsterdam
ER -
TY - GEN
A1 - Herzog, Benedict
A1 - Hönig, Timo
A1 - Schröder-Preikschat, Wolfgang
A1 - Plauth, Max
A1 - Köhler, Sven
A1 - Polze, Andreas
T1 - Bridging the Gap
BT - Energy-efficient Execution of Software Workloads on Heterogeneous Hardware Components
T2 - e-Energy '19: Proceedings of the Tenth ACM International Conference on Future Energy Systems
N2 - The recent restructuring of the electricity grid (i.e., smart grid) introduces a number of challenges for today's large-scale computing systems. To operate reliable and efficient, computing systems must adhere not only to technical limits (i.e., thermal constraints) but they must also reduce operating costs, for example, by increasing their energy efficiency. Efforts to improve the energy efficiency, however, are often hampered by inflexible software components that hardly adapt to underlying hardware characteristics. In this paper, we propose an approach to bridge the gap between inflexible software and heterogeneous hardware architectures. Our proposal introduces adaptive software components that dynamically adapt to heterogeneous processing units (i.e., accelerators) during runtime to improve the energy efficiency of computing systems.
Y1 - 2019
SN - 978-1-4503-6671-7
U6 - https://doi.org/10.1145/3307772.3330176
SP - 428
EP - 430
PB - Association for Computing Machinery
CY - New York
ER -
TY - GEN
A1 - Hesse, Günter
A1 - Matthies, Christoph
A1 - Sinzig, Werner
A1 - Uflacker, Matthias
T1 - Adding Value by Combining Business and Sensor Data
BT - an Industry 4.0 Use Case
T2 - Database Systems for Advanced Applications
N2 - Industry 4.0 and the Internet of Things are recent developments that have lead to the creation of new kinds of manufacturing data. Linking this new kind of sensor data to traditional business information is crucial for enterprises to take advantage of the data’s full potential. In this paper, we present a demo which allows experiencing this data integration, both vertically between technical and business contexts and horizontally along the value chain. The tool simulates a manufacturing company, continuously producing both business and sensor data, and supports issuing ad-hoc queries that answer specific questions related to the business. In order to adapt to different environments, users can configure sensor characteristics to their needs.
KW - Industry 4.0
KW - Internet of Things
KW - Data integration
Y1 - 2019
SN - 978-3-030-18590-9
SN - 978-3-030-18589-3
U6 - https://doi.org/10.1007/978-3-030-18590-9_80
SN - 0302-9743
SN - 1611-3349
VL - 11448
SP - 528
EP - 532
PB - Springer
CY - Cham
ER -
TY - JOUR
A1 - Hildebrandt, Dieter
T1 - A software reference architecture for service-oriented 3D geovisualization systems
JF - ISPRS International Journal of Geo-Information
KW - 3D geovisualization
KW - software reference architecture
KW - spatial data infrastructure
KW - service-oriented architecture
KW - standardization
KW - image-based representation
Y1 - 2014
U6 - https://doi.org/10.3390/ijgi3041445
SN - 2220-9964
VL - 3
IS - 4
SP - 1445
EP - 1490
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Hildebrandt, Dieter
A1 - Döllner, Jürgen
T1 - Service-oriented, standards-based 3D geovisualization : potential and challenges
N2 - The application of the architectural concept of service-oriented architectures (SOA) in combination with open standards when building distributed, 3D geovisualization systems offers the potential to cover and take advantage of the opportunities and demands created by the rise of ubiquitous computer networks and the Internet as well as to overcome prevalent interoperability barriers. In this paper, based on a literature study and our own experiences, we discuss the potential and challenges that arise when building standards-based, distributed systems according to the SOA paradigm for 3D geovisualization, with a particular focus on 3D geovirtual environments and virtual 3D city models. First, we briefly introduce fundamentals of the SOA paradigm, identify requirements for service-oriented 3D geovisualization systems, and present an architectural framework that relates SOA concepts, geovisualization concepts, and standardization proposals by the Open Geospatial Consortium in a common frame of reference. Next, we discuss the potential and challenges driven by the SOA paradigm on four different levels of abstraction, namely service fundamentals, service composition, interaction services, performance, and overarching aspects, and we discuss those driven by standardization. We further exemplify and substantiate the discussion in the scope of a case study and the image-based provisioning of and interaction with visual representations of remote virtual 3D city models.
Y1 - 2010
UR - http://www.sciencedirect.com/science/journal/01989715
U6 - https://doi.org/10.1016/j.compenvurbsys.2010.05.003
SN - 0198-9715
ER -
TY - JOUR
A1 - Hildebrandt, Dieter
A1 - Timm, Robert
T1 - An assisting, constrained 3D navigation technique for multiscale virtual 3D city models
JF - Geoinformatica : an international journal on advances of computer science for geographic information systems
N2 - Virtual 3D city models serve as integration platforms for complex geospatial and georeferenced information and as medium for effective communication of spatial information. In order to explore these information spaces, navigation techniques for controlling the virtual camera are required to facilitate wayfinding and movement. However, navigation is not a trivial task and many available navigation techniques do not support users effectively and efficiently with their respective skills and tasks. In this article, we present an assisting, constrained navigation technique for multiscale virtual 3D city models that is based on three basic principles: users point to navigate, users are lead by suggestions, and the exploitation of semantic, multiscale, hierarchical structurings of city models. The technique particularly supports users with low navigation and virtual camera control skills but is also valuable for experienced users. It supports exploration, search, inspection, and presentation tasks, is easy to learn and use, supports orientation, is efficient, and yields effective view properties. In particular, the technique is suitable for interactive kiosks and mobile devices with a touch display and low computing resources and for use in mobile situations where users only have restricted resources for operating the application. We demonstrate the validity of the proposed navigation technique by presenting an implementation and evaluation results. The implementation is based on service-oriented architectures, standards, and image-based representations and allows exploring massive virtual 3D city models particularly on mobile devices with limited computing resources. Results of a user study comparing the proposed navigation technique with standard techniques suggest that the proposed technique provides the targeted properties, and that it is more advantageous to novice than to expert users.
KW - Virtual 3D city model
KW - Multiscale modeling
KW - View navigation
KW - Virtual camera control
KW - Mobile device
KW - Distributed 3D geovisualization
Y1 - 2014
U6 - https://doi.org/10.1007/s10707-013-0189-8
SN - 1384-6175
SN - 1573-7624
VL - 18
IS - 3
SP - 537
EP - 567
PB - Springer
CY - Dordrecht
ER -
TY - JOUR
A1 - Hirschfeld, Robert
A1 - Perscheid, Michael
A1 - Haupt, Michael
T1 - Explicit use-case representation in object-oriented programming languages
JF - ACM SIGPLAN notices
N2 - Use-cases are considered an integral part of most contemporary development processes since they describe a software system's expected behavior from the perspective of its prospective users. However, the presence of and traceability to use-cases is increasingly lost in later more code-centric development activities. Use-cases, being well-encapsulated at the level of requirements descriptions, eventually lead to crosscutting concerns in system design and source code. Tracing which parts of the system contribute to which use-cases is therefore hard and so limits understandability.
In this paper, we propose an approach to making use-cases first-class entities in both the programming language and the runtime environment. Having use-cases present in the code and the running system will allow developers, maintainers, and operators to easily associate their units of work with what matters to the users. We suggest the combination of use-cases, acceptance tests, and dynamic analysis to automatically associate source code with use-cases. We present UseCasePy, an implementation of our approach to use-case-centered development in Python, and its application to the Django Web framework.
KW - design
KW - languages
KW - use-cases
KW - separation of concerns
KW - traceability
Y1 - 2012
U6 - https://doi.org/10.1145/2168696.2047856
SN - 0362-1340
VL - 47
IS - 2
SP - 51
EP - 60
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Ion, Alexandra
A1 - Lindlbauer, David
A1 - Herholz, Philipp
A1 - Alexa, Marc
A1 - Baudisch, Patrick Markus
T1 - Understanding Metamaterial Mechanisms
JF - Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems
N2 - In this paper, we establish the underlying foundations of mechanisms that are composed of cell structures-known as metamaterial mechanisms. Such metamaterial mechanisms were previously shown to implement complete mechanisms in the cell structure of a 3D printed material, without the need for assembly. However, their design is highly challenging. A mechanism consists of many cells that are interconnected and impose constraints on each other. This leads to unobvious and non-linear behavior of the mechanism, which impedes user design. In this work, we investigate the underlying topological constraints of such cell structures and their influence on the resulting mechanism. Based on these findings, we contribute a computational design tool that automatically creates a metamaterial mechanism from user-defined motion paths. This tool is only feasible because our novel abstract representation of the global constraints highly reduces the search space of possible cell arrangements.
KW - Metamaterials
KW - fabrication
KW - computational design
Y1 - 2019
SN - 978-1-4503-5970-2
U6 - https://doi.org/10.1145/3290605.3300877
PB - Association for Computing Machinery
CY - New York
ER -
TY - JOUR
A1 - Isailović, Dušan
A1 - Stojanovic, Vladeta
A1 - Trapp, Matthias
A1 - Richter, Rico
A1 - Hajdin, Rade
A1 - Döllner, Jürgen Roland Friedrich
T1 - Bridge damage
BT - detection, IFC-based semantic enrichment and visualization
JF - Automation in construction : an international research journal
N2 - Building Information Modeling (BIM) representations of bridges enriched by inspection data will add tremendous value to future Bridge Management Systems (BMSs). This paper presents an approach for point cloud-based detection of spalling damage, as well as integrating damage components into a BIM via semantic enrichment of an as-built Industry Foundation Classes (IFC) model. An approach for generating the as-built BIM, geometric reconstruction of detected damage point clusters and semantic-enrichment of the corresponding IFC model is presented. Multiview-classification is used and evaluated for the detection of spalling damage features. The semantic enrichment of as-built IFC models is based on injecting classified and reconstructed damage clusters back into the as-built IFC, thus generating an accurate as-is IFC model compliant to the BMS inspection requirements.
KW - damage detection
KW - building information modeling
KW - 3D point clouds
KW - multiview classification
KW - bridge management systems
Y1 - 2020
U6 - https://doi.org/10.1016/j.autcon.2020.103088
SN - 0926-5805
SN - 1872-7891
VL - 112
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Kaitoua, Abdulrahman
A1 - Rabl, Tilmann
A1 - Markl, Volker
T1 - A distributed data exchange engine for polystores
JF - Information technology : methods and applications of informatics and information technology
JF - Information technology : Methoden und innovative Anwendungen der Informatik und Informationstechnik
N2 - There is an increasing interest in fusing data from heterogeneous sources. Combining data sources increases the utility of existing datasets, generating new information and creating services of higher quality. A central issue in working with heterogeneous sources is data migration: In order to share and process data in different engines, resource intensive and complex movements and transformations between computing engines, services, and stores are necessary.
Muses is a distributed, high-performance data migration engine that is able to interconnect distributed data stores by forwarding, transforming, repartitioning, or broadcasting data among distributed engines' instances in a resource-, cost-, and performance-adaptive manner. As such, it performs seamless information sharing across all participating resources in a standard, modular manner. We show an overall improvement of 30 % for pipelining jobs across multiple engines, even when we count the overhead of Muses in the execution time. This performance gain implies that Muses can be used to optimise large pipelines that leverage multiple engines.
KW - distributed systems
KW - data migration
KW - data transformation
KW - big data
KW - engine
KW - data integration
Y1 - 2020
U6 - https://doi.org/10.1515/itit-2019-0037
SN - 1611-2776
SN - 2196-7032
VL - 62
IS - 3-4
SP - 145
EP - 156
PB - De Gruyter
CY - Berlin
ER -
TY - JOUR
A1 - Kastius, Alexander
A1 - Schlosser, Rainer
T1 - Dynamic pricing under competition using reinforcement learning
JF - Journal of revenue and pricing management
N2 - Dynamic pricing is considered a possibility to gain an advantage over competitors in modern online markets. The past advancements in Reinforcement Learning (RL) provided more capable algorithms that can be used to solve pricing problems. In this paper, we study the performance of Deep Q-Networks (DQN) and Soft Actor Critic (SAC) in different market models. We consider tractable duopoly settings, where optimal solutions derived by dynamic programming techniques can be used for verification, as well as oligopoly settings, which are usually intractable due to the curse of dimensionality. We find that both algorithms provide reasonable results, while SAC performs better than DQN. Moreover, we show that under certain conditions, RL algorithms can be forced into collusion by their competitors without direct communication.
KW - Dynamic pricing
KW - Competition
KW - Reinforcement learning
KW - E-commerce
KW - Price collusion
Y1 - 2021
U6 - https://doi.org/10.1057/s41272-021-00285-3
SN - 1476-6930
SN - 1477-657X
VL - 21
IS - 1
SP - 50
EP - 63
PB - Springer Nature Switzerland AG
CY - Cham
ER -
TY - JOUR
A1 - Khomenko, Victor
A1 - Schäfer, Mark
A1 - Vogler, Walter
A1 - Wollowski, Ralf
T1 - STG decomposition strategies in combination with unfolding
N2 - For synthesising efficient asynchronous circuits one has to deal with the state space explosion problem. In order to alleviate this problem one can decompose the STG into smaller components. This paper deals with the decomposition method of Vogler and Wollowski and introduces several strategies for its efficient implementations. Furthermore, this approach is combined with another method to alleviate state space explosion, which is based on Petri net unfoldings. The developed algorithms are compared by means of benchmark examples, and the experimental results show significant improvement in terms of memory usage and runtime compared with other existing methods.
Y1 - 2009
UR - http://www.springerlink.com/content/100460
U6 - https://doi.org/10.1007/s00236-009-0102-y
SN - 0001-5903
ER -
TY - JOUR
A1 - Koehler, Friedrich
A1 - Koehler, Kerstin
A1 - Deckwart, Oliver
A1 - Prescher, Sandra
A1 - Wegscheider, Karl
A1 - Winkler, Sebastian
A1 - Vettorazzi, Eik
A1 - Polze, Andreas
A1 - Stangl, Karl
A1 - Hartmann, Oliver
A1 - Marx, Almuth
A1 - Neuhaus, Petra
A1 - Scherf, Michael
A1 - Kirwan, Bridget-Anne
A1 - Anker, Stefan D.
T1 - Telemedical Interventional Management in Heart Failure II (TIM-HF2), a randomised, controlled trial investigating the impact of telemedicine on unplanned cardiovascular hospitalisations and mortality in heart failure patients
BT - study design and description of the intervention
JF - European Journal of Heart Failure
N2 - Background Heart failure (HF) is a complex, chronic condition that is associated with debilitating symptoms, all of which necessitate close follow-up by health care providers. Lack of disease monitoring may result in increased mortality and more frequent hospital readmissions for decompensated HF. Remote patient management (RPM) in this patient population may help to detect early signs and symptoms of cardiac decompensation, thus enabling a prompt initiation of the appropriate treatment and care before a manifestation of HF decompensation. Objective The objective of the present article is to describe the design of a new trial investigating the impact of RPM on unplanned cardiovascular hospitalisations and mortality in HF patients. Methods The TIM-HF2 trial is designed as a prospective, randomised, controlled, parallel group, open (with randomisation concealment), multicentre trial with pragmatic elements introduced for data collection. Eligible patients with HF are randomised (1:1) to either RPM + usual care or to usual care only and are followed for 12 months. The primary outcome is the percentage of days lost due to unplanned cardiovascular hospitalisations or all-cause death. The main secondary outcomes are all-cause and cardiovascular mortality. Conclusion The TIM-HF2 trial will provide important prospective data on the potential beneficial effect of telemedical monitoring and RPM on unplanned cardiovascular hospitalisations and mortality in HF patients.
KW - Chronic heart failure
KW - Telemonitoring
KW - Remote patient management
KW - Hospitalisation
Y1 - 2018
U6 - https://doi.org/10.1002/ejhf.1300
SN - 1388-9842
SN - 1879-0844
VL - 20
IS - 10
SP - 1485
EP - 1493
PB - Wiley
CY - Hoboken
ER -