TY - JOUR A1 - Quinzan, Francesco A1 - Göbel, Andreas A1 - Wagner, Markus A1 - Friedrich, Tobias T1 - Evolutionary algorithms and submodular functions BT - benefits of heavy-tailed mutations JF - Natural computing : an innovative journal bridging biosciences and computer sciences ; an international journal N2 - A core operator of evolutionary algorithms (EAs) is the mutation. Recently, much attention has been devoted to the study of mutation operators with dynamic and non-uniform mutation rates. Following up on this area of work, we propose a new mutation operator and analyze its performance on the (1 + 1) Evolutionary Algorithm (EA). Our analyses show that this mutation operator competes with pre-existing ones, when used by the (1 + 1) EA on classes of problems for which results on the other mutation operators are available. We show that the (1 + 1) EA using our mutation operator finds a (1/3)-approximation ratio on any non-negative submodular function in polynomial time. We also consider the problem of maximizing a symmetric submodular function under a single matroid constraint and show that the (1 + 1) EA using our operator finds a (1/3)-approximation within polynomial time. This performance matches that of combinatorial local search algorithms specifically designed to solve these problems and outperforms them with constant probability. Finally, we evaluate the performance of the (1 + 1) EA using our operator experimentally by considering two applications: (a) the maximum directed cut problem on real-world graphs of different origins, with up to 6.6 million vertices and 56 million edges and (b) the symmetric mutual information problem using a four month period air pollution data set. In comparison with uniform mutation and a recently proposed dynamic scheme, our operator comes out on top on these instances. KW - Evolutionary algorithms KW - Mutation operators KW - Submodular functions KW - Matroids Y1 - 2021 U6 - https://doi.org/10.1007/s11047-021-09841-7 SN - 1572-9796 VL - 20 IS - 3 SP - 561 EP - 575 PB - Springer Science + Business Media B.V. CY - Dordrecht ER - TY - JOUR A1 - Magkos, Sotirios A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - Suppression of cone-beam artefacts with Direct Iterative Reconstruction Computed Tomography Trajectories (DIRECTT) JF - Journal of imaging : open access journal N2 - The reconstruction of cone-beam computed tomography data using filtered back-projection algorithms unavoidably results in severe artefacts. We describe how the Direct Iterative Reconstruction of Computed Tomography Trajectories (DIRECTT) algorithm can be combined with a model of the artefacts for the reconstruction of such data. The implementation of DIRECTT results in reconstructed volumes of superior quality compared to the conventional algorithms. KW - iteration method KW - signal processing KW - X-ray imaging KW - computed tomography Y1 - 2021 U6 - https://doi.org/10.3390/jimaging7080147 SN - 2313-433X VL - 7 IS - 8 PB - MDPI CY - Basel ER - TY - JOUR A1 - Perugia, Giulia A1 - Paetzel-Prüsmann, Maike A1 - Alanenpää, Madelene A1 - Castellano, Ginevra T1 - I can see it in your eyes BT - Gaze as an implicit cue of uncanniness and task performance in repeated interactions with robots JF - Frontiers in robotics and AI N2 - Over the past years, extensive research has been dedicated to developing robust platforms and data-driven dialog models to support long-term human-robot interactions. However, little is known about how people's perception of robots and engagement with them develop over time and how these can be accurately assessed through implicit and continuous measurement techniques. In this paper, we explore this by involving participants in three interaction sessions with multiple days of zero exposure in between. Each session consists of a joint task with a robot as well as two short social chats with it before and after the task. We measure participants' gaze patterns with a wearable eye-tracker and gauge their perception of the robot and engagement with it and the joint task using questionnaires. Results disclose that aversion of gaze in a social chat is an indicator of a robot's uncanniness and that the more people gaze at the robot in a joint task, the worse they perform. In contrast with most HRI literature, our results show that gaze toward an object of shared attention, rather than gaze toward a robotic partner, is the most meaningful predictor of engagement in a joint task. Furthermore, the analyses of gaze patterns in repeated interactions disclose that people's mutual gaze in a social chat develops congruently with their perceptions of the robot over time. These are key findings for the HRI community as they entail that gaze behavior can be used as an implicit measure of people's perception of robots in a social chat and of their engagement and task performance in a joint task. KW - perception of robots KW - long-term interaction KW - mutual gaze KW - engagement KW - uncanny valley Y1 - 2021 U6 - https://doi.org/10.3389/frobt.2021.645956 SN - 2296-9144 VL - 8 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Oosthoek, Kris A1 - Dörr, Christian T1 - Cyber security threats to bitcoin exchanges BT - adversary exploitation and laundering techniques JF - IEEE transactions on network and service management : a publication of the IEEE N2 - Bitcoin is gaining traction as an alternative store of value. Its market capitalization transcends all other cryptocurrencies in the market. But its high monetary value also makes it an attractive target to cyber criminal actors. Hacking campaigns usually target an ecosystem's weakest points. In Bitcoin, the exchange platforms are one of them. Each exchange breach is a threat not only to direct victims, but to the credibility of Bitcoin's entire ecosystem. Based on an extensive analysis of 36 breaches of Bitcoin exchanges, we show the attack patterns used to exploit Bitcoin exchange platforms using an industry standard for reporting intelligence on cyber security breaches. Based on this we are able to provide an overview of the most common attack vectors, showing that all except three hacks were possible due to relatively lax security. We show that while the security regimen of Bitcoin exchanges is subpar compared to other financial service providers, the use of stolen credentials, which does not require any hacking, is decreasing. We also show that the amount of BTC taken during a breach is decreasing, as well as the exchanges that terminate after being breached. Furthermore we show that overall security posture has improved, but still has major flaws. To discover adversarial methods post-breach, we have analyzed two cases of BTC laundering. Through this analysis we provide insight into how exchange platforms with lax cyber security even further increase the intermediary risk introduced by them into the Bitcoin ecosystem. KW - Bitcoin KW - Computer crime KW - Cryptography KW - Ecosystems KW - Currencies KW - Industries KW - Vocabulary KW - cryptocurrency exchanges KW - cyber KW - security KW - cyber threat intelligence KW - attacks KW - vulnerabilities KW - forensics Y1 - 2021 U6 - https://doi.org/10.1109/TNSM.2020.3046145 SN - 1932-4537 VL - 18 IS - 2 SP - 1616 EP - 1628 PB - IEEE CY - New York ER - TY - JOUR A1 - Kühl, Tim A1 - Münzer, Stefan T1 - Learning about a serious disease BT - when a personalized message is harmful unless you are happy JF - Journal of computer assisted learning : JCAL N2 - According to the personalization principle, addressing learners by means of a personalized compared to a nonpersonalized message can foster learning. Interestingly, though, a recent study found that the personalization principle can invert for aversive contents. The present study investigated whether the negative effect of a personalized message for an aversive content can be compensated when learners are in a happy mood. It was hypothesized that the negative effect of a personalized compared to a nonpersonalized message would only be observable for participants in a sad mood, while for participants in a happy mood a personalized message should be beneficial. A 2 x 2 between-subject design with mood (happy vs. sad) and personalization (personalized vs. nonpersonalized message) was used (N = 125 University students). Mood was experimentally varied prior to learning. Learning outcomes were measured by a retention and a transfer test. Results were essentially in line with the assumption: For participants in the sad mood condition, a negative effect of a personalized message was observable for retention and transfer. For participants in the happy mood condition, a positive effect of personalized message was observable for retention, but no effect for transfer. Note that the manipulation check measure for the mood induction procedure did not detect differences between conditions; this may be due to a shortcoming of the used measure (as indicated by an additional evaluation study). The study emphasizes the importance to consider the inherent emotional content of a topic, such as its aversive nature, since the emotional content of a topic can be a boundary condition for design principles in multimedia learning. The study also highlights the complex interplay of externally induced and inherently arising emotions. KW - cognitive load KW - emotional design KW - mood KW - multimedia learning KW - personalization principle Y1 - 2021 U6 - https://doi.org/10.1111/jcal.12571 SN - 0266-4909 SN - 1365-2729 VL - 37 IS - 5 SP - 1312 EP - 1323 PB - Wiley-Blackwell CY - Oxford [u.a.] ER - TY - JOUR A1 - Schneider, Sven A1 - Lambers, Leen A1 - Orejas, Fernando T1 - A logic-based incremental approach to graph repair featuring delta preservation JF - International journal on software tools for technology transfer : STTT N2 - We introduce a logic-based incremental approach to graph repair, generating a sound and complete (upon termination) overview of least-changing graph repairs from which a user may select a graph repair based on non-formalized further requirements. This incremental approach features delta preservation as it allows to restrict the generation of graph repairs to delta-preserving graph repairs, which do not revert the additions and deletions of the most recent consistency-violating graph update. We specify consistency of graphs using the logic of nested graph conditions, which is equivalent to first-order logic on graphs. Technically, the incremental approach encodes if and how the graph under repair satisfies a graph condition using the novel data structure of satisfaction trees, which are adapted incrementally according to the graph updates applied. In addition to the incremental approach, we also present two state-based graph repair algorithms, which restore consistency of a graph independent of the most recent graph update and which generate additional graph repairs using a global perspective on the graph under repair. We evaluate the developed algorithms using our prototypical implementation in the tool AutoGraph and illustrate our incremental approach using a case study from the graph database domain. KW - Nested graph conditions KW - Graph repair KW - Model repair KW - Consistency KW - restoration KW - Delta preservation KW - Graph databases KW - Model-driven KW - engineering Y1 - 2021 U6 - https://doi.org/10.1007/s10009-020-00584-x SN - 1433-2779 SN - 1433-2787 VL - 23 IS - 3 SP - 369 EP - 410 PB - Springer CY - Berlin ; Heidelberg 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 - 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 - Maldonado-Mahauad, Jorge A1 - Valdiviezo, Javier A1 - Carvallo, Juan Pablo A1 - Samaniego-Erazo, Nicolay T1 - The MOOC-CEDIA Observatory BT - Study of the Current Situation of MOOCs and Recommendations To Improve Their Adoption in Ecuadorian Universities JF - EMOOCs 2021 N2 - In the last few years, an important amount of Massive Open Online Courses (MOOCS) has been made available to the worldwide community, mainly by European and North American universities (i.e. United States). Since its emergence, the adoption of these educational resources has been widely studied by several research groups and universities with the aim of understanding their evolution and impact in educational models, through the time. In the case of Latin America, data from the MOOC-UC Observatory (updated until 2018) shows that, the adoption of these courses by universities in the region has been slow and heterogeneous. In the specific case of Ecuador, although some data is available, there is lack of information regarding the construction, publication and/or adoption of such courses by universities in the country. Moreover, there are not updated studies designed to identify and analyze the barriers and factors affecting the adoption of MOOCs in the country. The aim of this work is to present the MOOC-CEDIA Observatory, a web platform that offers interactive visualizations on the adoption of MOOCs in Ecuador. The main results of the study show that: (1) until 2020 there have been 99 MOOCs in Ecuador, (2) the domains of MOOCs are mostly related to applied sciences, social sciences and natural sciences, with the humanities being the least covered, (3) Open edX and Moodle are the most widely used platforms to deploy such courses. It is expected that the conclusions drawn from this analysis, will allow the design of recommendations aimed to promote the creation and use of quality MOOCs in Ecuador and help institutions to chart the route for their adoption, both for internal use by their community but also by society in general. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-517153 SN - 978-3-86956-512-5 VL - 2021 SP - 143 EP - 158 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Pawassar, Christian Matthias A1 - Tiberius, Victor T1 - Virtual reality in health care BT - Bibliometric analysis JF - JMIR Serious Games N2 - Background: Research into the application of virtual reality technology in the health care sector has rapidly increased, resulting in a large body of research that is difficult to keep up with. Objective: We will provide an overview of the annual publication numbers in this field and the most productive and influential countries, journals, and authors, as well as the most used, most co-occurring, and most recent keywords. Methods: Based on a data set of 356 publications and 20,363 citations derived from Web of Science, we conducted a bibliometric analysis using BibExcel, HistCite, and VOSviewer. Results: The strongest growth in publications occurred in 2020, accounting for 29.49% of all publications so far. The most productive countries are the United States, the United Kingdom, and Spain; the most influential countries are the United States, Canada, and the United Kingdom. The most productive journals are the Journal of Medical Internet Research (JMIR), JMIR Serious Games, and the Games for Health Journal; the most influential journals are Patient Education and Counselling, Medical Education, and Quality of Life Research. The most productive authors are Riva, del Piccolo, and Schwebel; the most influential authors are Finset, del Piccolo, and Eide. The most frequently occurring keywords other than “virtual” and “reality” are “training,” “trial,” and “patients.” The most relevant research themes are communication, education, and novel treatments; the most recent research trends are fitness and exergames. Conclusions: The analysis shows that the field has left its infant state and its specialization is advancing, with a clear focus on patient usability. KW - virtual reality KW - healthcare KW - bibliometric analysis KW - literature review KW - citation analysis KW - VR KW - usability KW - review KW - health care Y1 - 2021 U6 - https://doi.org/10.2196/32721 SN - 2291-9279 VL - 9 SP - 1 EP - 19 PB - JMIR Publications CY - Toronto, Kanada ET - 4 ER - TY - JOUR A1 - Huang, Yizhen A1 - Richter, Eric A1 - Kleickmann, Thilo A1 - Wiepke, Axel A1 - Richter, Dirk T1 - Classroom complexity affects student teachers’ behavior in a VR classroom JF - Computers & education : an international journal N2 - Student teachers often struggle to keep track of everything that is happening in the classroom, and particularly to notice and respond when students cause disruptions. The complexity of the classroom environment is a potential contributing factor that has not been empirically tested. In this experimental study, we utilized a virtual reality (VR) classroom to examine whether classroom complexity affects the likelihood of student teachers noticing disruptions and how they react after noticing. Classroom complexity was operationalized as the number of disruptions and the existence of overlapping disruptions (multidimensionality) as well as the existence of parallel teaching tasks (simultaneity). Results showed that student teachers (n = 50) were less likely to notice the scripted disruptions, and also less likely to respond to the disruptions in a comprehensive and effortful manner when facing greater complexity. These results may have implications for both teacher training and the design of VR for training or research purpose. This study contributes to the field from two aspects: 1) it revealed how features of the classroom environment can affect student teachers' noticing of and reaction to disruptions; and 2) it extends the functionality of the VR environment-from a teacher training tool to a testbed of fundamental classroom processes that are difficult to manipulate in real-life. KW - Augmented and virtual reality KW - Simulations KW - Improving classroom KW - teaching KW - Media in education KW - Pedagogical issues Y1 - 2021 U6 - https://doi.org/10.1016/j.compedu.2020.104100 SN - 0360-1315 SN - 1873-782X VL - 163 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Shekhar, Sumit A1 - Reimann, Max A1 - Mayer, Maximilian A1 - Semmo, Amir A1 - Pasewaldt, Sebastian A1 - Döllner, Jürgen A1 - Trapp, Matthias T1 - Interactive photo editing on smartphones via intrinsic decomposition JF - Computer graphics forum : journal of the European Association for Computer Graphics N2 - Intrinsic decomposition refers to the problem of estimating scene characteristics, such as albedo and shading, when one view or multiple views of a scene are provided. The inverse problem setting, where multiple unknowns are solved given a single known pixel-value, is highly under-constrained. When provided with correlating image and depth data, intrinsic scene decomposition can be facilitated using depth-based priors, which nowadays is easy to acquire with high-end smartphones by utilizing their depth sensors. In this work, we present a system for intrinsic decomposition of RGB-D images on smartphones and the algorithmic as well as design choices therein. Unlike state-of-the-art methods that assume only diffuse reflectance, we consider both diffuse and specular pixels. For this purpose, we present a novel specularity extraction algorithm based on a multi-scale intensity decomposition and chroma inpainting. At this, the diffuse component is further decomposed into albedo and shading components. We use an inertial proximal algorithm for non-convex optimization (iPiano) to ensure albedo sparsity. Our GPU-based visual processing is implemented on iOS via the Metal API and enables interactive performance on an iPhone 11 Pro. Further, a qualitative evaluation shows that we are able to obtain high-quality outputs. Furthermore, our proposed approach for specularity removal outperforms state-of-the-art approaches for real-world images, while our albedo and shading layer decomposition is faster than the prior work at a comparable output quality. Manifold applications such as recoloring, retexturing, relighting, appearance editing, and stylization are shown, each using the intrinsic layers obtained with our method and/or the corresponding depth data. KW - CCS Concepts KW - center dot Computing KW - methodologie KW - Image-based rendering KW - Image KW - processing KW - Computational photography Y1 - 2021 U6 - https://doi.org/10.1111/cgf.142650 SN - 0167-7055 SN - 1467-8659 VL - 40 SP - 497 EP - 510 PB - Blackwell CY - Oxford ER - TY - CHAP A1 - Abramova, Olga A1 - Gladkaya, Margarita A1 - Krasnova, Hanna T1 - An unusual encounter with oneself BT - exploring the impact of self-view on online meeting outcomes T2 - ICIS 2021: IS and the future of work N2 - Helping overcome distance, the use of videoconferencing tools has surged during the pandemic. To shed light on the consequences of videoconferencing at work, this study takes a granular look at the implications of the self-view feature for meeting outcomes. Building on self-awareness research and self-regulation theory, we argue that by heightening the state of self-awareness, self-view engagement depletes participants’ mental resources and thereby can undermine online meeting outcomes. Evaluation of our theoretical model on a sample of 179 employees reveals a nuanced picture. Self-view engagement while speaking and while listening is positively associated with self-awareness, which, in turn, is negatively associated with satisfaction with meeting process, perceived productivity, and meeting enjoyment. The criticality of the communication role is put forward: looking at self while listening to other attendees has a negative direct and indirect effect on meeting outcomes; however, looking at self while speaking produces equivocal effects. Y1 - 2021 UR - https://aisel.aisnet.org/icis2021/is_future_work/is_future_work/16 PB - AIS Electronic Library (AISeL) CY - [Erscheinungsort nicht ermittelbar] ER - TY - JOUR A1 - Şahin, Muhittin A1 - Egloffstein, Marc A1 - Bothe, Max A1 - Rohloff, Tobias A1 - Schenk, Nathanael A1 - Schwerer, Florian A1 - Ifenthaler, Dirk T1 - Behavioral Patterns in Enterprise MOOCs at openSAP JF - EMOOCs 2021 Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-517350 SN - 978-3-86956-512-5 VL - 2021 SP - 281 EP - 288 PB - Universitätsverlag Potsdam CY - Potsdam 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 - Vitagliano, Gerardo A1 - Jiang, Lan A1 - Naumann, Felix T1 - Detecting layout templates in complex multiregion files JF - Proceedings of the VLDB Endowment N2 - Spreadsheets are among the most commonly used file formats for data management, distribution, and analysis. Their widespread employment makes it easy to gather large collections of data, but their flexible canvas-based structure makes automated analysis difficult without heavy preparation. One of the common problems that practitioners face is the presence of multiple, independent regions in a single spreadsheet, possibly separated by repeated empty cells. We define such files as "multiregion" files. In collections of various spreadsheets, we can observe that some share the same layout. We present the Mondrian approach to automatically identify layout templates across multiple files and systematically extract the corresponding regions. Our approach is composed of three phases: first, each file is rendered as an image and inspected for elements that could form regions; then, using a clustering algorithm, the identified elements are grouped to form regions; finally, every file layout is represented as a graph and compared with others to find layout templates. We compare our method to state-of-the-art table recognition algorithms on two corpora of real-world enterprise spreadsheets. Our approach shows the best performances in detecting reliable region boundaries within each file and can correctly identify recurring layouts across files. Y1 - 2022 U6 - https://doi.org/10.14778/3494124.3494145 SN - 2150-8097 VL - 15 IS - 3 SP - 646 EP - 658 PB - Association for Computing Machinery CY - New York ER - TY - GEN A1 - Benson, Lawrence A1 - Makait, Hendrik A1 - Rabl, Tilmann T1 - Viper BT - An Efficient Hybrid PMem-DRAM Key-Value Store T2 - Zweitveröffentlichungen der Universität Potsdam : Reihe der Digital Engineering Fakultät N2 - Key-value stores (KVSs) have found wide application in modern software systems. For persistence, their data resides in slow secondary storage, which requires KVSs to employ various techniques to increase their read and write performance from and to the underlying medium. Emerging persistent memory (PMem) technologies offer data persistence at close-to-DRAM speed, making them a promising alternative to classical disk-based storage. However, simply drop-in replacing existing storage with PMem does not yield good results, as block-based access behaves differently in PMem than on disk and ignores PMem's byte addressability, layout, and unique performance characteristics. In this paper, we propose three PMem-specific access patterns and implement them in a hybrid PMem-DRAM KVS called Viper. We employ a DRAM-based hash index and a PMem-aware storage layout to utilize the random-write speed of DRAM and efficient sequential-write performance PMem. Our evaluation shows that Viper significantly outperforms existing KVSs for core KVS operations while providing full data persistence. Moreover, Viper outperforms existing PMem-only, hybrid, and disk-based KVSs by 4-18x for write workloads, while matching or surpassing their get performance. T3 - Zweitveröffentlichungen der Universität Potsdam : Reihe der Digital Engineering Fakultät - 20 KW - memory Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-559664 SN - 2150-8097 IS - 9 ER - TY - JOUR A1 - Rüdian, Sylvio Leo A1 - Vladova, Gergana T1 - Kostenfreie Onlinekurse nachhaltig mit personalisiertem Marketing finanzieren BT - ein Vorschlag zur synergetischen Kombination zweier datengetriebener Geschäftsmodelle JF - HMD Praxis der Wirtschaftsinformatik N2 - Selbstbestimmtes Lernen mit Onlinekursen findet zunehmend mehr Akzeptanz in unserer Gesellschaft. Lernende können mithilfe von Onlinekursen selbst festlegen, was sie wann lernen und Kurse können durch vielfältige Adaptionen an den Lernfortschritt der Nutzer angepasst und individualisiert werden. Auf der einen Seite ist eine große Zielgruppe für diese Lernangebote vorhanden. Auf der anderen Seite sind die Erstellung von Onlinekursen, ihre Bereitstellung, Wartung und Betreuung kostenintensiv, wodurch hochwertige Angebote häufig kostenpflichtig angeboten werden müssen, um als Anbieter zumindest kostenneutral agieren zu können. In diesem Beitrag erörtern und diskutieren wir ein offenes, nachhaltiges datengetriebenes zweiseitiges Geschäftsmodell zur Verwertung geprüfter Onlinekurse und deren kostenfreie Bereitstellung für jeden Lernenden. Kern des Geschäftsmodells ist die Nutzung der dabei entstehenden Verhaltensdaten, die daraus mögliche Ableitung von Persönlichkeitsmerkmalen und Interessen und deren Nutzung im kommerziellen Kontext. Dies ist eine bei der Websuche bereits weitläufig akzeptierte Methode, welche nun auf den Lernkontext übertragen wird. Welche Möglichkeiten, Herausforderungen, aber auch Barrieren überwunden werden müssen, damit das Geschäftsmodell nachhaltig und ethisch vertretbar funktioniert, werden zwei unabhängige, jedoch synergetisch verbundene Geschäftsmodelle vorgestellt und diskutiert. Zusätzlich wurde die Akzeptanz und Erwartung der Zielgruppe für das vorgestellte Geschäftsmodell untersucht, um notwendige Kernressourcen für die Praxis abzuleiten. Die Ergebnisse der Untersuchung zeigen, dass das Geschäftsmodell von den Nutzer*innen grundlegend akzeptiert wird. 10 % der Befragten würden es bevorzugen, mit virtuellen Assistenten – anstelle mit Tutor*innen zu lernen. Zudem ist der Großteil der Nutzer*innen sich nicht darüber bewusst, dass Persönlichkeitsmerkmale anhand des Nutzerverhaltens abgeleitet werden können. KW - Onlinekurse KW - Big Data KW - Geschäftsmodell KW - Werbung KW - Marketing KW - Canvas Y1 - 2021 U6 - https://doi.org/10.1365/s40702-021-00720-4 SN - 1436-3011 VL - 58 IS - 3 SP - 507 EP - 520 PB - Springer Vieweg CY - Wiesbaden ER - TY - BOOK A1 - Baltzer, Wanda A1 - Hradilak, Theresa A1 - Pfennigschmidt, Lara A1 - Prestin, Luc Maurice A1 - Spranger, Moritz A1 - Stadlinger, Simon A1 - Wendt, Leo A1 - Lincke, Jens A1 - Rein, Patrick A1 - Church, Luke A1 - Hirschfeld, Robert T1 - An individual-centered approach to visualize people’s opinions and demographic information N2 - The noble way to substantiate decisions that affect many people is to ask these people for their opinions. For governments that run whole countries, this means asking all citizens for their views to consider their situations and needs. Organizations such as Africa's Voices Foundation, who want to facilitate communication between decision-makers and citizens of a country, have difficulty mediating between these groups. To enable understanding, statements need to be summarized and visualized. Accomplishing these goals in a way that does justice to the citizens' voices and situations proves challenging. Standard charts do not help this cause as they fail to create empathy for the people behind their graphical abstractions. Furthermore, these charts do not create trust in the data they are representing as there is no way to see or navigate back to the underlying code and the original data. To fulfill these functions, visualizations would highly benefit from interactions to explore the displayed data, which standard charts often only limitedly provide. To help improve the understanding of people's voices, we developed and categorized 80 ideas for new visualizations, new interactions, and better connections between different charts, which we present in this report. From those ideas, we implemented 10 prototypes and two systems that integrate different visualizations. We show that this integration allows consistent appearance and behavior of visualizations. The visualizations all share the same main concept: representing each individual with a single dot. To realize this idea, we discuss technologies that efficiently allow the rendering of a large number of these dots. With these visualizations, direct interactions with representations of individuals are achievable by clicking on them or by dragging a selection around them. This direct interaction is only possible with a bidirectional connection from the visualization to the data it displays. We discuss different strategies for bidirectional mappings and the trade-offs involved. Having unified behavior across visualizations enhances exploration. For our prototypes, that includes grouping, filtering, highlighting, and coloring of dots. Our prototyping work was enabled by the development environment Lively4. We explain which parts of Lively4 facilitated our prototyping process. Finally, we evaluate our approach to domain problems and our developed visualization concepts. Our work provides inspiration and a starting point for visualization development in this domain. Our visualizations can improve communication between citizens and their government and motivate empathetic decisions. Our approach, combining low-level entities to create visualizations, provides value to an explorative and empathetic workflow. We show that the design space for visualizing this kind of data has a lot of potential and that it is possible to combine qualitative and quantitative approaches to data analysis. N2 - Der noble Weg, Entscheidungen, die viele Menschen betreffen, zu begründen, besteht darin, diese Menschen nach ihrer Meinung zu fragen. Für Regierungen, die ganze Länder führen, bedeutet dies, alle Bürger nach ihrer Meinung zu fragen, um ihre Situationen und Bedürfnisse zu berücksichtigen. Organisationen wie die Africa's Voices Foundation, die die Kommunikation zwischen Entscheidungsträgern und Bürgern eines Landes erleichtern wollen, haben Schwierigkeiten, zwischen diesen Gruppen zu vermitteln. Um Verständnis zu ermöglichen, müssen die Aussagen zusammengefasst und visualisiert werden. Diese Ziele auf eine Weise zu erreichen, die den Stimmen und Situationen der Bürgerinnen und Bürger gerecht wird, erweist sich als Herausforderung. Standardgrafiken helfen dabei nicht weiter, da es ihnen nicht gelingt, Empathie für die Menschen hinter ihren grafischen Abstraktionen zu schaffen. Darüber hinaus schaffen diese Diagramme kein Vertrauen in die Daten, die sie darstellen, da es keine Möglichkeit gibt, den verwendeten Code und die Originaldaten zu sehen oder zu ihnen zurück zu navigieren. Um diese Funktionen zu erfüllen, würden Visualisierungen sehr von Interaktionen zur Erkundung der angezeigten Daten profitieren, die Standardgrafiken oft nur begrenzt bieten. Um das Verständnis der Stimmen der Menschen zu verbessern, haben wir 80 Ideen für neue Visualisierungen, neue Interaktionen und bessere Verbindungen zwischen verschiedenen Diagrammen entwickelt und kategorisiert, die wir in diesem Bericht vorstellen. Aus diesen Ideen haben wir 10 Prototypen und zwei Systeme implementiert, die verschiedene Visualisierungen integrieren. Wir zeigen, dass diese Integration ein einheitliches Erscheinungsbild und Verhalten der Visualisierungen ermöglicht. Die Visualisierungen haben alle das gleiche Grundkonzept: Jedes Individuum wird durch einen einzigen Punkt dargestellt. Um diese Idee zu verwirklichen, diskutieren wir Technologien, die die effiziente Darstellung einer großen Anzahl dieser Punkte ermöglichen. Mit diesen Visualisierungen sind direkte Interaktionen mit Darstellungen von Individuen möglich, indem man auf sie klickt oder eine Auswahl um sie herumzieht. Diese direkte Interaktion ist nur mit einer bidirektionalen Verbindung von der Visualisierung zu den angezeigten Daten möglich. Wir diskutieren verschiedene Strategien für bidirektionale Mappings und die damit verbundenen Kompromisse. Ein einheitliches Verhalten über Visualisierungen hinweg verbessert die Exploration. Für unsere Prototypen umfasst dies Gruppierung, Filterung, Hervorhebung und Einfärbung von Punkten. Unsere Arbeit an den Prototypen wurde durch die Entwicklungsumgebung Lively4 ermöglicht. Wir erklären, welche Teile von Lively4 unseren Prototyping-Prozess erleichtert haben. Schließlich bewerten wir unsere Herangehensweise an Domänenprobleme und die von uns entwickelten Visualisierungskonzepte. Unsere Arbeit liefert Inspiration und einen Ausgangspunkt für die Entwicklung von Visualisierungen in diesem Bereich. Unsere Visualisierungen können die Kommunikation zwischen Bürgern und ihrer Regierung verbessern und einfühlsame Entscheidungen motivieren. Unser Ansatz, bei dem wir niedrigstufige Entitäten zur Erstellung von Visualisierungen kombinieren, bietet einen wertvollen Ansatz für einen explorativen und einfühlsamen Arbeitsablauf. Wir zeigen, dass der Designraum für die Visualisierung dieser Art von Daten ein großes Potenzial hat und dass es möglich ist, qualitative und quantitative Ansätze zur Datenanalyse zu kombinieren. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 136 KW - data visualization KW - demographic information KW - visualization concept exploration KW - web-based development environment KW - Datenvisualisierung KW - demografische Informationen KW - Visualisierungskonzept-Exploration KW - web-basierte Entwicklungsumgebung Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-491457 SN - 978-3-86956-504-0 SN - 1613-5652 SN - 2191-1665 IS - 136 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Seitz, Klara A1 - Lincke, Jens A1 - Rein, Patrick A1 - Hirschfeld, Robert T1 - Language and tool support for 3D crochet patterns BT - virtual crochet with a graph structure N2 - Crochet is a popular handcraft all over the world. While other techniques such as knitting or weaving have received technical support over the years through machines, crochet is still a purely manual craft. Not just the act of crochet itself is manual but also the process of creating instructions for new crochet patterns, which is barely supported by domain specific digital solutions. This leads to unstructured and often also ambiguous and erroneous pattern instructions. In this report, we propose a concept to digitally represent crochet patterns. This format incorporates crochet techniques which allows domain specific support for crochet pattern designers during the pattern creation and instruction writing process. As contributions, we present a thorough domain analysis, the concept of a graph structure used as domain specific language to specify crochet patterns and a prototype of a projectional editor using the graph as representation format of patterns and a diagramming system to visualize them in 2D and 3D. By analyzing the domain, we learned about crochet techniques and pain points of designers in their pattern creation workflow. These insights are the basis on which we defined the pattern representation. In order to evaluate our concept, we built a prototype by which the feasibility of the concept is shown and we tested the software with professional crochet designers who approved of the concept. N2 - Häkeln ist eine weltweit verbreitete Handarbeitskunst. Obwohl andere Techniken, wie stricken und weben über die Zeit maschinelle Unterstützung erhalten haben, ist Häkeln noch heute ein komplett manueller Vorgang. Nicht nur das Häkeln an sich, sondern auch der Prozess zur Anleitungserstellung von neuen Häkeldesigns ist kaum unterstützt mit digitalen Lösungen. In dieser Arbeit stellen wir ein Konzept vor, das Häkelanleitungen digital repräsentiert. Das entwickelte Format integriert Häkeltechniken, wodurch wir den Prozess des Anleitungschreibens für Designer spezifisch für die Häkeldomäne unterstützen können. Als Beiträge analysieren wir umfassend die Häkeldomäne, entwickeln ein Konzept zur Repräsentation von Häkelanleitungen basierend auf einer Graphenstruktur als domänenspezifische Sprache und implementieren einen projektionalen Editor, der auf der besagten Graphenstruktur aufbaut und weiterhin die erstellten Anleitungen als schematische Darstellung in 2D und 3D visualisiert. Durch die Analyse der Domäne lernen wir Häkeltechniken und Schwachstellen beim Ablauf des Anleitungserstellens kennen. Basierend auf diesen Erkenntnissen entwickeln wir das digitale Format, um Anleitungen zu repräsentieren. Für die Evaluierung unseres Konzepts, haben wir einen Prototypen implementiert, der die Machbarkeit demonstriert. Zudem haben wir die Software von professionellen Häkeldesignern testen lassen, die unsere Herangehensweise gutheißen. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 137 KW - crochet KW - visual language KW - tools KW - computer-aided design KW - Häkeln KW - visuelle Sprache KW - Werkzeuge KW - rechnerunterstütztes Konstruieren Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-492530 SN - 978-3-86956-505-7 SN - 1613-5652 SN - 2191-1665 IS - 137 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Bartz, Christian A1 - Krestel, Ralf T1 - Deep learning for computer vision in the art domain BT - proceedings of the master seminar on practical introduction to deep learning for computer vision, HPI WS 20/21 N2 - In recent years, computer vision algorithms based on machine learning have seen rapid development. In the past, research mostly focused on solving computer vision problems such as image classification or object detection on images displaying natural scenes. Nowadays other fields such as the field of cultural heritage, where an abundance of data is available, also get into the focus of research. In the line of current research endeavours, we collaborated with the Getty Research Institute which provided us with a challenging dataset, containing images of paintings and drawings. In this technical report, we present the results of the seminar "Deep Learning for Computer Vision". In this seminar, students of the Hasso Plattner Institute evaluated state-of-the-art approaches for image classification, object detection and image recognition on the dataset of the Getty Research Institute. The main challenge when applying modern computer vision methods to the available data is the availability of annotated training data, as the dataset provided by the Getty Research Institute does not contain a sufficient amount of annotated samples for the training of deep neural networks. However, throughout the report we show that it is possible to achieve satisfying to very good results, when using further publicly available datasets, such as the WikiArt dataset, for the training of machine learning models. N2 - Methoden zur Anwendung von maschinellem Lernen für das maschinelle Sehen haben sich in den letzten Jahren stark weiterentwickelt. Dabei konzentrierte sich die Forschung hauptsächlich auf die Lösung von Problemen im Bereich der Bildklassifizierung, oder der Objekterkennung aus Bildern mit natürlichen Motiven. Mehr und mehr kommen zusätzlich auch andere Inhaltsbereiche, vor allem aus dem kulturellen Umfeld in den Fokus der Forschung. Kulturforschungsinstitute, wie das Getty Research Institute, besitzen eine Vielzahl von digitalisierten Dokumenten, die bisher noch nicht analysiert wurden. Im Rahmen einer Zusammenarbeit, überließ das Getty Research Institute uns einen Datensatz, bestehend aus Photos von Kunstwerken. In diesem technischen Bericht präsentieren wir die Ergebnisse des Masterseminars "Deep Learning for Computer Vision", in dem Studierende des Hasso-Plattner-Instituts den Stand der Kunst, bei der Anwendung von Bildklassifizierungs, Objekterkennungs und Image Retrieval Algorithmen evaluierten. Eine besondere Schwierigkeit war, dass es nicht möglich ist bestehende Verfahren direkt auf dem Datensatz anzuwenden, da keine, bzw. kaum Annotationen für das Training von Machine Learning Modellen verfügbar sind. In den einzelnen Teilen des Berichts zeigen wir jedoch, dass es möglich ist unter Zuhilfenahme von weiteren öffentlich verfügbaren Datensätzen, wie dem WikiArt Datensatz, zufriedenstellende bis sehr gute Ergebnisse für die einzelnen Analyseaufgaben zu erreichen. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 139 KW - computer vision KW - cultural heritage KW - art analysis KW - maschinelles Sehen KW - kulturelles Erbe KW - Kunstanalyse Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-512906 SN - 978-3-86956-514-9 SN - 1613-5652 SN - 2191-1665 IS - 139 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Maximova, Maria A1 - Schneider, Sven A1 - Giese, Holger T1 - Interval probabilistic timed graph transformation systems N2 - The formal modeling and analysis is of crucial importance for software development processes following the model based approach. We present the formalism of Interval Probabilistic Timed Graph Transformation Systems (IPTGTSs) as a high-level modeling language. This language supports structure dynamics (based on graph transformation), timed behavior (based on clocks, guards, resets, and invariants as in Timed Automata (TA)), and interval probabilistic behavior (based on Discrete Interval Probability Distributions). That is, for the probabilistic behavior, the modeler using IPTGTSs does not need to provide precise probabilities, which are often impossible to obtain, but rather provides a probability range instead from which a precise probability is chosen nondeterministically. In fact, this feature on capturing probabilistic behavior distinguishes IPTGTSs from Probabilistic Timed Graph Transformation Systems (PTGTSs) presented earlier. Following earlier work on Interval Probabilistic Timed Automata (IPTA) and PTGTSs, we also provide an analysis tool chain for IPTGTSs based on inter-formalism transformations. In particular, we provide in our tool AutoGraph a translation of IPTGTSs to IPTA and rely on a mapping of IPTA to Probabilistic Timed Automata (PTA) to allow for the usage of the Prism model checker. The tool Prism can then be used to analyze the resulting PTA w.r.t. probabilistic real-time queries asking for worst-case and best-case probabilities to reach a certain set of target states in a given amount of time. N2 - Die formale Modellierung und Analyse ist für Softwareentwicklungsprozesse nach dem modellbasierten Ansatz von entscheidender Bedeutung. Wir präsentieren den Formalismus von Interval Probabilistic Timed Graph Transformation Systems (IPTGTS) als Modellierungssprache auf hoher abstrakter Ebene. Diese Sprache unterstützt Strukturdynamik (basierend auf Graphtransformation), zeitgesteuertes Verhalten (basierend auf Clocks, Guards, Resets und Invarianten wie in Timed Automata (TA)) und intervallwahrscheinliches Verhalten (basierend auf diskreten Intervallwahrscheinlichkeitsverteilungen). Das heißt, für das probabilistische Verhalten muss der Modellierer, der IPTGTS verwendet, keine genauen Wahrscheinlichkeiten bereitstellen, die oft nicht zu bestimmen sind, sondern stattdessen einen Wahrscheinlichkeitsbereich bereitstellen, aus dem eine genaue Wahrscheinlichkeit nichtdeterministisch ausgewählt wird. Tatsächlich unterscheidet diese Funktion zur Erfassung des probabilistischen Verhaltens IPTGTS von den zuvor vorgestellten PTGTS (Probabilistic Timed Graph Transformation Systems). Nach früheren Arbeiten zu Intervall Probabilistic Timed Automata (IPTA) und PTGTS bieten wir auch eine Analyse-Toolkette für IPTGTS, die auf Interformalismus-Transformationen basiert. Insbesondere bieten wir in unserem Tool AutoGraph eine Übersetzung von IPTGTSs in IPTA und stützen uns auf eine Zuordnung von IPTA zu probabilistischen zeitgesteuerten Automaten (PTA), um die Verwendung des Prism-Modellprüfers zu ermöglichen. Das Werkzeug Prism kann dann verwendet werden, um den resultierenden PTA bezüglich probabilistische Echtzeitabfragen (in denen nach Worst-Case- und Best-Case-Wahrscheinlichkeiten gefragt wird, um einen bestimmten Satz von Zielzuständen in einem bestimmten Zeitraum zu erreichen) zu analysieren. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 134 KW - cyber-physical systems KW - graph transformation systems KW - interval timed automata KW - timed automata KW - qualitative analysis KW - quantitative analysis KW - probabilistic timed systems KW - interval probabilistic timed systems KW - model checking KW - cyber-physikalische Systeme KW - Graphentransformationssysteme KW - Interval Timed Automata KW - Timed Automata KW - qualitative Analyse KW - quantitative Analyse KW - probabilistische zeitgesteuerte Systeme KW - interval probabilistische zeitgesteuerte Systeme KW - Modellprüfung Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-512895 SN - 978-3-86956-502-6 SN - 1613-5652 SN - 2191-1665 IS - 134 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Schneider, Sven A1 - Maximova, Maria A1 - Giese, Holger T1 - Probabilistic metric temporal graph logic N2 - Cyber-physical systems often encompass complex concurrent behavior with timing constraints and probabilistic failures on demand. The analysis whether such systems with probabilistic timed behavior adhere to a given specification is essential. When the states of the system can be represented by graphs, the rule-based formalism of Probabilistic Timed Graph Transformation Systems (PTGTSs) can be used to suitably capture structure dynamics as well as probabilistic and timed behavior of the system. The model checking support for PTGTSs w.r.t. properties specified using Probabilistic Timed Computation Tree Logic (PTCTL) has been already presented. Moreover, for timed graph-based runtime monitoring, Metric Temporal Graph Logic (MTGL) has been developed for stating metric temporal properties on identified subgraphs and their structural changes over time. In this paper, we (a) extend MTGL to the Probabilistic Metric Temporal Graph Logic (PMTGL) by allowing for the specification of probabilistic properties, (b) adapt our MTGL satisfaction checking approach to PTGTSs, and (c) combine the approaches for PTCTL model checking and MTGL satisfaction checking to obtain a Bounded Model Checking (BMC) approach for PMTGL. In our evaluation, we apply an implementation of our BMC approach in AutoGraph to a running example. N2 - Cyber-physische Systeme umfassen häufig ein komplexes nebenläufiges Verhalten mit Zeitbeschränkungen und probabilistischen Fehlern auf Anforderung. Die Analyse, ob solche Systeme mit probabilistischem gezeitetem Verhalten einer vorgegebenen Spezifikation entsprechen, ist essentiell. Wenn die Zustände des Systems durch Graphen dargestellt werden können, kann der regelbasierte Formalismus von probabilistischen gezeiteten Graphtransformationssystemen (PTGTSs) verwendet werden, um die Strukturdynamik sowie das probabilistische und gezeitete Verhalten des Systems geeignet zu erfassen. Die Modellprüfungsunterstützung für PTGTSs bzgl. Eigenschaften, die unter Verwendung von probabilistischer zeitgesteuerter Berechnungsbaumlogik (PTCTL) spezifiziert wurden, wurde bereits entwickelt. Darüber hinaus wurde das gezeitete graphenbasierte Laufzeitmonitoring mittels metrischer temporaler Graphlogik (MTGL) entwickelt, um metrische temporale Eigenschaften auf identifizierten Untergraphen und ihre strukturellen Änderungen über die Zeit zu erfassen. In diesem Artikel (a) erweitern wir MTGL auf die probabilistische metrische temporale Graphlogik (PMTGL), indem wir die Spezifikation probabilistischer Eigenschaften zulassen, (b) passen unseren MTGL-Prüfungsansatz auf PTGTSs an und (c) kombinieren die Ansätze für PTCTL-Modellprüfung und MTGL-Prüfung, um einen beschränkten Modellprüfungsansatz (BMC-Ansatz) für PMTGL zu erhalten. In unserer Auswertung wenden wir eine Implementierung unseres BMC-Ansatzes in AutoGraph auf ein Beispiel an. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 140 KW - cyber-physische Systeme KW - probabilistische gezeitete Systeme KW - qualitative Analyse KW - quantitative Analyse KW - Bounded Model Checking KW - cyber-physical systems KW - probabilistic timed systems KW - qualitative analysis KW - quantitative analysis KW - bounded model checking Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515066 SN - 978-3-86956-517-0 SN - 1613-5652 SN - 2191-1665 IS - 140 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - von Steinau-Steinrück, Robert A1 - Bruhn, Emma T1 - Der Impfmuffel im Arbeitsrecht JF - NJW spezial N2 - Trotz erfolgreicher Impfkampagne droht nach dem Sommer eine vierte Infektionswelle der Corona-Pandemie. Ob es dazu kommen wird, hängt maßgeblich davon ab, wie viele Menschen sich für eine Corona-Schutzimpfung entscheiden. Am Impfstoff mangelt es nicht mehr, dafür an der Impfbereitschaft. Viele Arbeitgeber fragen sich daher, was sie unternehmen können, um die Impfquote in ihren Betrieben zu erhöhen. Y1 - 2021 UR - https://beck-online.beck.de/Bcid/Y-300-Z-NJW-SPEZIAL-B-2021-S-498-N-1 SN - 1613-4621 VL - 18 IS - 16 SP - 498 EP - 499 PB - C.H. Beck CY - München ER - TY - JOUR A1 - von Steinau-Steinrück, Robert A1 - Jöris, Nils T1 - Brexit-Arbeitsrecht und die Folgen JF - NJW spezial N2 - Die Corona-Pandemie hat den Brexit ein wenig in den Hintergrund gedrängt. Dabei hat er gerade im Arbeitsrecht ganz erhebliche Auswirkungen. Über sie geben wir einen Überblick. Y1 - 2021 UR - https://beck-online.beck.de/Bcid/Y-300-Z-NJW-SPEZIAL-B-2021-S-242-N-1 SN - 1613-4621 VL - 18 IS - 8 SP - 242 EP - 243 PB - C.H. Beck CY - München ER - TY - JOUR A1 - von Steinau-Steinrück, Robert T1 - Was ist bei "Workation" und "Bleisure" rechtlich zu beachten? JF - NJW spezial N2 - Die Digitalisierung unseres Lebens löst die Grenzen zwischen Privat- und Berufsleben immer weiter auf. Bekanntes Beispiel ist das Homeoffice. Arbeitgeber begegnen aber auch zahlreichen weiteren Trends in diesem Zusammenhang. Dazu gehören „workation“, also die Verbindung zwischen Arbeit („work“) und Urlaub („vacation“) ebenso wie „bleisure“, dh die Verbindung von Dienstreisen („business“) und Urlaub („leisure“). Der Beitrag geht den rechtlichen Rahmenbedingungen hierfür nach. Y1 - 2021 UR - https://beck-online.beck.de/Bcid/Y-300-Z-NJW-SPEZIAL-B-2021-S-626-N-1 SN - 1613-4621 VL - 18 IS - 20 SP - 626 EP - 627 PB - C.H. Beck CY - München ER - TY - THES A1 - Rohloff, Tobias T1 - Learning analytics at scale BT - supporting learning and teaching in MOOCs with data-driven insights N2 - Digital technologies are paving the way for innovative educational approaches. The learning format of Massive Open Online Courses (MOOCs) provides a highly accessible path to lifelong learning while being more affordable and flexible than face-to-face courses. Thereby, thousands of learners can enroll in courses mostly without admission restrictions, but this also raises challenges. Individual supervision by teachers is barely feasible, and learning persistence and success depend on students' self-regulatory skills. Here, technology provides the means for support. The use of data for decision-making is already transforming many fields, whereas in education, it is still a young research discipline. Learning Analytics (LA) is defined as the measurement, collection, analysis, and reporting of data about learners and their learning contexts with the purpose of understanding and improving learning and learning environments. The vast amount of data that MOOCs produce on the learning behavior and success of thousands of students provides the opportunity to study human learning and develop approaches addressing the demands of learners and teachers. The overall purpose of this dissertation is to investigate the implementation of LA at the scale of MOOCs and to explore how data-driven technology can support learning and teaching in this context. To this end, several research prototypes have been iteratively developed for the HPI MOOC Platform. Hence, they were tested and evaluated in an authentic real-world learning environment. Most of the results can be applied on a conceptual level to other MOOC platforms as well. The research contribution of this thesis thus provides practical insights beyond what is theoretically possible. In total, four system components were developed and extended: (1) The Learning Analytics Architecture: A technical infrastructure to collect, process, and analyze event-driven learning data based on schema-agnostic pipelining in a service-oriented MOOC platform. (2) The Learning Analytics Dashboard for Learners: A tool for data-driven support of self-regulated learning, in particular to enable learners to evaluate and plan their learning activities, progress, and success by themselves. (3) Personalized Learning Objectives: A set of features to better connect learners' success to their personal intentions based on selected learning objectives to offer guidance and align the provided data-driven insights about their learning progress. (4) The Learning Analytics Dashboard for Teachers: A tool supporting teachers with data-driven insights to enable the monitoring of their courses with thousands of learners, identify potential issues, and take informed action. For all aspects examined in this dissertation, related research is presented, development processes and implementation concepts are explained, and evaluations are conducted in case studies. Among other findings, the usage of the learner dashboard in combination with personalized learning objectives demonstrated improved certification rates of 11.62% to 12.63%. Furthermore, it was observed that the teacher dashboard is a key tool and an integral part for teaching in MOOCs. In addition to the results and contributions, general limitations of the work are discussed—which altogether provide a solid foundation for practical implications and future research. N2 - Digitale Technologien sind Wegbereiter für innovative Bildungsansätze. Das Lernformat der Massive Open Online Courses (MOOCs) bietet einen einfachen und globalen Zugang zu lebenslangem Lernen und ist oft kostengünstiger und flexibler als klassische Präsenzlehre. Dabei können sich Tausende von Lernenden meist ohne Zulassungsbeschränkung in Kurse einschreiben, wodurch jedoch auch Herausforderungen entstehen. Eine individuelle Betreuung durch Lehrende ist kaum möglich und das Durchhaltevermögen und der Lernerfolg hängen von selbstregulatorischen Fähigkeiten der Lernenden ab. Hier bietet Technologie die Möglichkeit zur Unterstützung. Die Nutzung von Daten zur Entscheidungsfindung transformiert bereits viele Bereiche, aber im Bildungswesen ist dies noch eine junge Forschungsdisziplin. Als Learning Analytics (LA) wird das Messen, Erfassen, Analysieren und Auswerten von Daten über Lernende und ihren Lernkontext verstanden, mit dem Ziel, das Lernen und die Lernumgebungen zu verstehen und zu verbessern. Die riesige Menge an Daten, die MOOCs über das Lernverhalten und den Lernerfolg produzieren, bietet die Möglichkeit, das menschliche Lernen zu studieren und Ansätze zu entwickeln, die den Anforderungen von Lernenden und Lehrenden gerecht werden. Der Schwerpunkt dieser Dissertation liegt auf der Implementierung von LA für die Größenordnung von MOOCs und erforscht dabei, wie datengetriebene Technologie das Lernen und Lehren in diesem Kontext unterstützen kann. Zu diesem Zweck wurden mehrere Forschungsprototypen iterativ für die HPI-MOOC-Plattform entwickelt. Daher wurden diese in einer authentischen und realen Lernumgebung getestet und evaluiert. Die meisten Ergebnisse lassen sich auf konzeptioneller Ebene auch auf andere MOOC-Plattformen übertragen, wodurch der Forschungsbeitrag dieser Arbeit praktische Erkenntnisse über das theoretisch Mögliche hinaus liefert. Insgesamt wurden vier Systemkomponenten entwickelt und erweitert: (1) Die LA-Architektur: Eine technische Infrastruktur zum Sammeln, Verarbeiten und Analysieren von ereignisgesteuerten Lerndaten basierend auf einem schemaagnostischem Pipelining in einer serviceorientierten MOOC-Plattform. (2) Das LA-Dashboard für Lernende: Ein Werkzeug zur datengesteuerten Unterstützung der Selbstregulierung, insbesondere um Lernende in die Lage zu versetzen, ihre Lernaktivitäten, ihren Fortschritt und ihren Lernerfolg selbst zu evaluieren und zu planen. (3) Personalisierte Lernziele: Eine Reihe von Funktionen, um den Lernerfolg besser mit persönlichen Absichten zu verknüpfen, die auf ausgewählten Lernzielen basieren, um Leitlinien anzubieten und die bereitgestellten datengetriebenen Einblicke über den Lernfortschritt darauf abzustimmen. (4) Das LA-Dashboard für Lehrende: Ein Hilfsmittel, das Lehrkräfte mit datengetriebenen Erkenntnissen unterstützt, um ihre Kurse mit Tausenden von Lernenden zu überblicken, mögliche Probleme zu erkennen und fundierte Maßnahmen zu ergreifen. Für alle untersuchten Aspekte dieser Dissertation werden verwandte Forschungsarbeiten vorgestellt, Entwicklungsprozesse und Implementierungskonzepte erläutert und Evaluierungen in Fallstudien durchgeführt. Unter anderem konnte durch den Einsatz des Dashboards für Lernende in Kombination mit personalisierten Lernzielen verbesserte Zertifizierungsraten von 11,62% bis 12,63% nachgewiesen werden. Außerdem wurde beobachtet, dass das Dashboard für Lehrende ein entscheidendes Werkzeug und ein integraler Bestandteil für die Lehre in MOOCs ist. Neben den Ergebnissen und Beiträgen werden generelle Einschränkungen der Arbeit diskutiert, die insgesamt eine fundierte Grundlage für praktische Implikationen und zukünftige Forschungsvorhaben schaffen. KW - Learning Analytics KW - MOOCs KW - Self-Regulated Learning KW - E-Learning KW - Service-Oriented Architecture KW - Online Learning Environments Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-526235 ER - TY - THES A1 - Torcato Mordido, Gonçalo Filipe T1 - Diversification, compression, and evaluation methods for generative adversarial networks N2 - Generative adversarial networks (GANs) have been broadly applied to a wide range of application domains since their proposal. In this thesis, we propose several methods that aim to tackle different existing problems in GANs. Particularly, even though GANs are generally able to generate high-quality samples, the diversity of the generated set is often sub-optimal. Moreover, the common increase of the number of models in the original GANs framework, as well as their architectural sizes, introduces additional costs. Additionally, even though challenging, the proper evaluation of a generated set is an important direction to ultimately improve the generation process in GANs. We start by introducing two diversification methods that extend the original GANs framework to multiple adversaries to stimulate sample diversity in a generated set. Then, we introduce a new post-training compression method based on Monte Carlo methods and importance sampling to quantize and prune the weights and activations of pre-trained neural networks without any additional training. The previous method may be used to reduce the memory and computational costs introduced by increasing the number of models in the original GANs framework. Moreover, we use a similar procedure to quantize and prune gradients during training, which also reduces the communication costs between different workers in a distributed training setting. We introduce several topology-based evaluation methods to assess data generation in different settings, namely image generation and language generation. Our methods retrieve both single-valued and double-valued metrics, which, given a real set, may be used to broadly assess a generated set or separately evaluate sample quality and sample diversity, respectively. Moreover, two of our metrics use locality-sensitive hashing to accurately assess the generated sets of highly compressed GANs. The analysis of the compression effects in GANs paves the way for their efficient employment in real-world applications. Given their general applicability, the methods proposed in this thesis may be extended beyond the context of GANs. Hence, they may be generally applied to enhance existing neural networks and, in particular, generative frameworks. N2 - Generative adversarial networks (GANs) wurden seit ihrer Einführung in einer Vielzahl von Anwendungsbereichen eingesetzt. In dieser Dissertation schlagen wir einige Verfahren vor, die darauf abzielen, verschiedene bestehende Probleme von GANs zu lösen. Insbesondere, fokussieren wir uns auf das Problem das GANs zwar qualitative hochwertige Samples generieren können, aber die Diversität ist oft sub-optimal. Darüber hinaus, stellt die allgemein übliche Zunahme der Anzahl der Modelle unter dem ursprünglichen GAN-Framework, als auch deren Modellgröße weitere Aufwendungskosten dar. Abschließend, ist die richtige Evaluierung einer generierten Menge, wenn auch herausfordernd, eine wichtige Forschungsrichtung, um letztendlich den Generierungsprozess von GANs zu verbessern. Wir beginnen mit der Einführung von zwei Diversifizierungsmethoden die das ursprüngliche GAN-Framework um mehrere Gegenspieler erweitern, um die Diversität zu erhöhen. Um den zusätzlichen Speicher- und Rechenaufwand zu reduzieren, führen wir dann eine neue Kompressionsmethode ein. Diese Methode basiert auf den Monte-Carlo-Methoden und Importance Sampling, für das Quantisieren und Pruning der Gewichte und Aktivierungen von schon trainierten neuronalen Netzwerken ohne zusätzliches Trainieren. Wir erweitern die erwähne Methode zusätzlich für das Quantisieren und Pruning von Gradienten während des Trainierens, was die Kommunikationskosten zwischen verschiedenen sogenannten „Workern“ in einer verteilten Trainingsumgebung reduziert. Bezüglich der Bewertung der generierten Samples, stellen wir mehrere typologie basierte Evaluationsmethoden vor, die sich auf Bild-und Text konzentrieren. Um verschiedene Anwendungsfälle zu erfassen, liefern unsere vorgestellten Methoden einwertige und doppelwertige Metriken. Diese können einerseits dazu genutzt werden, generierte Samples, oder die Qualität und Verteilung der Samples anhand einer Menge von echten Samples zu bewerten. Außerdem, verwenden zwei unserer vorgestellten Metriken so genanntes locality-sensitive Hashing, um die generierten Samples von stark komprimierten GANs genau zu bewerten. Die Analyse von Kompressionseffekten in GANs ebnet den Weg für ihren effizienten Einsatz für reale Anwendungen. Aufgrund der allgemeinen Anwendungsmöglichkeit von GANs, können die in dieser Arbeit vorgestellten Methoden auch über Kontext von GANs hinaus erweitert werden. Daher könnten sie allgemein auf existierende neuronale Netzwerke angewandt werden und insbesondere auf generative Frameworks. KW - deep learning KW - generative adversarial networks KW - erzeugende gegnerische Netzwerke KW - tiefes Lernen Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-535460 ER - TY - CHAP A1 - Jacqmin, Julien A1 - Özdemir, Paker Doğu A1 - Fell Kurban, Caroline A1 - Tunç Pekkan, Zelha A1 - Koskinen, Johanna A1 - Suonpää, Maija A1 - Seng, Cheyvuth A1 - Carlon, May Kristine Jonson A1 - Gayed, John Maurice A1 - Cross, Jeffrey S. A1 - Langseth, Inger A1 - Jacobsen, Dan Yngve A1 - Haugsbakken, Halvdan A1 - Bethge, Joseph A1 - Serth, Sebastian A1 - Staubitz, Thomas A1 - Wuttke, Tobias A1 - Nordemann, Oliver A1 - Das, Partha-Pratim A1 - Meinel, Christoph A1 - Ponce, Eva A1 - Srinath, Sindhu A1 - Allegue, Laura A1 - Perach, Shai A1 - Alexandron, Giora A1 - Corti, Paola A1 - Baudo, Valeria A1 - Turró, Carlos A1 - Moura Santos, Ana A1 - Nilsson, Charlotta A1 - Maldonado-Mahauad, Jorge A1 - Valdiviezo, Javier A1 - Carvallo, Juan Pablo A1 - Samaniego-Erazo, Nicolay A1 - Poce, Antonella A1 - Re, Maria Rosaria A1 - Valente, Mara A1 - Karp Gershon, Sa’ar A1 - Ruipérez-Valiente, José A. A1 - Despujol, Ignacio A1 - Busquets, Jaime A1 - Kerr, John A1 - Lorenz, Anja A1 - Schön, Sandra A1 - Ebner, Martin A1 - Wittke, Andreas A1 - Beirne, Elaine A1 - Nic Giolla Mhichíl, Mairéad A1 - Brown, Mark A1 - Mac Lochlainn, Conchúr A1 - Topali, Paraskevi A1 - Chounta, Irene-Angelica A1 - Ortega-Arranz, Alejandro A1 - Villagrá-Sobrino, Sara L. A1 - Martínez-Monés, Alejandra A1 - Blackwell, Virginia Katherine A1 - Wiltrout, Mary Ellen A1 - Rami Gaddem, Mohamed A1 - Hernández Reyes, César Augusto A1 - Nagahama, Toru A1 - Buchem, Ilona A1 - Okatan, Ebru A1 - Khalil, Mohammad A1 - Casiraghi, Daniela A1 - Sancassani, Susanna A1 - Brambilla, Federica A1 - Mihaescu, Vlad A1 - Andone, Diana A1 - Vasiu, Radu A1 - Şahin, Muhittin A1 - Egloffstein, Marc A1 - Bothe, Max A1 - Rohloff, Tobias A1 - Schenk, Nathanael A1 - Schwerer, Florian A1 - Ifenthaler, Dirk A1 - Hense, Julia A1 - Bernd, Mike ED - Meinel, Christoph ED - Staubitz, Thomas ED - Schweiger, Stefanie ED - Friedl, Christian ED - Kiers, Janine ED - Ebner, Martin ED - Lorenz, Anja ED - Ubachs, George ED - Mongenet, Catherine ED - Ruipérez-Valiente, José A. ED - Cortes Mendez, Manoel T1 - EMOOCs 2021 N2 - From June 22 to June 24, 2021, Hasso Plattner Institute, Potsdam, hosted the seventh European MOOC Stakeholder Summit (EMOOCs 2021) together with the eighth ACM Learning@Scale Conference. Due to the COVID-19 situation, the conference was held fully online. The boost in digital education worldwide as a result of the pandemic was also one of the main topics of this year’s EMOOCs. All institutions of learning have been forced to transform and redesign their educational methods, moving from traditional models to hybrid or completely online models at scale. The learnings, derived from practical experience and research, have been explored in EMOOCs 2021 in six tracks and additional workshops, covering various aspects of this field. In this publication, we present papers from the conference’s Experience Track, the Policy Track, the Business Track, the International Track, and the Workshops. KW - e-learning KW - microcredential KW - MOOC KW - digital education KW - experience KW - online course design KW - online course creation KW - higher education Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-510300 SN - 978-3-86956-512-5 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Bethge, Joseph A1 - Serth, Sebastian A1 - Staubitz, Thomas A1 - Wuttke, Tobias A1 - Nordemann, Oliver A1 - Das, Partha-Pratim A1 - Meinel, Christoph T1 - TransPipe BT - A Pipeline for Automated Transcription and Translation of Videos JF - EMOOCs 2021 N2 - Online learning environments, such as Massive Open Online Courses (MOOCs), often rely on videos as a major component to convey knowledge. However, these videos exclude potential participants who do not understand the lecturer’s language, regardless of whether that is due to language unfamiliarity or aural handicaps. Subtitles and/or interactive transcripts solve this issue, ease navigation based on the content, and enable indexing and retrieval by search engines. Although there are several automated speech-to-text converters and translation tools, their quality varies and the process of integrating them can be quite tedious. Thus, in practice, many videos on MOOC platforms only receive subtitles after the course is already finished (if at all) due to a lack of resources. This work describes an approach to tackle this issue by providing a dedicated tool, which is closing this gap between MOOC platforms and transcription and translation tools and offering a simple workflow that can easily be handled by users with a less technical background. The proposed method is designed and evaluated by qualitative interviews with three major MOOC providers. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516943 VL - 2021 SP - 79 EP - 94 PB - Universitätsverlag Potsdam CY - Potsdam 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 - Perscheid, Cindy T1 - Integrative biomarker detection on high-dimensional gene expression data sets BT - a survey on prior knowledge approaches JF - Briefings in bioinformatics N2 - Gene expression data provide the expression levels of tens of thousands of genes from several hundred samples. These data are analyzed to detect biomarkers that can be of prognostic or diagnostic use. Traditionally, biomarker detection for gene expression data is the task of gene selection. The vast number of genes is reduced to a few relevant ones that achieve the best performance for the respective use case. Traditional approaches select genes based on their statistical significance in the data set. This results in issues of robustness, redundancy and true biological relevance of the selected genes. Integrative analyses typically address these shortcomings by integrating multiple data artifacts from the same objects, e.g. gene expression and methylation data. When only gene expression data are available, integrative analyses instead use curated information on biological processes from public knowledge bases. With knowledge bases providing an ever-increasing amount of curated biological knowledge, such prior knowledge approaches become more powerful. This paper provides a thorough overview on the status quo of biomarker detection on gene expression data with prior biological knowledge. We discuss current shortcomings of traditional approaches, review recent external knowledge bases, provide a classification and qualitative comparison of existing prior knowledge approaches and discuss open challenges for this kind of gene selection. KW - gene selection KW - external knowledge bases KW - biomarker detection KW - gene KW - expression KW - prior knowledge Y1 - 2021 U6 - https://doi.org/10.1093/bib/bbaa151 SN - 1467-5463 SN - 1477-4054 VL - 22 IS - 3 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Perscheid, Cindy T1 - Comprior BT - Facilitating the implementation and automated benchmarking of prior knowledge-based feature selection approaches on gene expression data sets JF - BMC Bioinformatics N2 - Background Reproducible benchmarking is important for assessing the effectiveness of novel feature selection approaches applied on gene expression data, especially for prior knowledge approaches that incorporate biological information from online knowledge bases. However, no full-fledged benchmarking system exists that is extensible, provides built-in feature selection approaches, and a comprehensive result assessment encompassing classification performance, robustness, and biological relevance. Moreover, the particular needs of prior knowledge feature selection approaches, i.e. uniform access to knowledge bases, are not addressed. As a consequence, prior knowledge approaches are not evaluated amongst each other, leaving open questions regarding their effectiveness. Results We present the Comprior benchmark tool, which facilitates the rapid development and effortless benchmarking of feature selection approaches, with a special focus on prior knowledge approaches. Comprior is extensible by custom approaches, offers built-in standard feature selection approaches, enables uniform access to multiple knowledge bases, and provides a customizable evaluation infrastructure to compare multiple feature selection approaches regarding their classification performance, robustness, runtime, and biological relevance. Conclusion Comprior allows reproducible benchmarking especially of prior knowledge approaches, which facilitates their applicability and for the first time enables a comprehensive assessment of their effectiveness KW - Feature selection KW - Prior knowledge KW - Gene expression KW - Reproducible benchmarking Y1 - 2021 U6 - https://doi.org/10.1186/s12859-021-04308-z SN - 1471-2105 VL - 22 SP - 1 EP - 15 PB - Springer Nature CY - London ER - TY - JOUR A1 - Loster, Michael A1 - Koumarelas, Ioannis A1 - Naumann, Felix T1 - Knowledge transfer for entity resolution with siamese neural networks JF - ACM journal of data and information quality N2 - The integration of multiple data sources is a common problem in a large variety of applications. Traditionally, handcrafted similarity measures are used to discover, merge, and integrate multiple representations of the same entity-duplicates-into a large homogeneous collection of data. Often, these similarity measures do not cope well with the heterogeneity of the underlying dataset. In addition, domain experts are needed to manually design and configure such measures, which is both time-consuming and requires extensive domain expertise.
We propose a deep Siamese neural network, capable of learning a similarity measure that is tailored to the characteristics of a particular dataset. With the properties of deep learning methods, we are able to eliminate the manual feature engineering process and thus considerably reduce the effort required for model construction. In addition, we show that it is possible to transfer knowledge acquired during the deduplication of one dataset to another, and thus significantly reduce the amount of data required to train a similarity measure. We evaluated our method on multiple datasets and compare our approach to state-of-the-art deduplication methods. Our approach outperforms competitors by up to +26 percent F-measure, depending on task and dataset. In addition, we show that knowledge transfer is not only feasible, but in our experiments led to an improvement in F-measure of up to +4.7 percent. KW - Entity resolution KW - duplicate detection KW - transfer learning KW - neural KW - networks KW - metric learning KW - similarity learning KW - data quality Y1 - 2021 U6 - https://doi.org/10.1145/3410157 SN - 1936-1955 SN - 1936-1963 VL - 13 IS - 1 PB - Association for Computing Machinery CY - New York ER - TY - JOUR A1 - Navarro, Marisa A1 - Orejas, Fernando A1 - Pino, Elvira A1 - Lambers, Leen T1 - A navigational logic for reasoning about graph properties JF - Journal of logical and algebraic methods in programming N2 - Graphs play an important role in many areas of Computer Science. In particular, our work is motivated by model-driven software development and by graph databases. For this reason, it is very important to have the means to express and to reason about the properties that a given graph may satisfy. With this aim, in this paper we present a visual logic that allows us to describe graph properties, including navigational properties, i.e., properties about the paths in a graph. The logic is equipped with a deductive tableau method that we have proved to be sound and complete. KW - Graph logic KW - Algebraic methods KW - Formal modelling KW - Specification Y1 - 2021 U6 - https://doi.org/10.1016/j.jlamp.2020.100616 SN - 2352-2208 SN - 2352-2216 VL - 118 PB - Elsevier Science CY - Amsterdam [u.a.] ER - TY - THES A1 - Makowski, Silvia T1 - Discriminative Models for Biometric Identification using Micro- and Macro-Movements of the Eyes N2 - Human visual perception is an active process. Eye movements either alternate between fixations and saccades or follow a smooth pursuit movement in case of moving targets. Besides these macroscopic gaze patterns, the eyes perform involuntary micro-movements during fixations which are commonly categorized into micro-saccades, drift and tremor. Eye movements are frequently studied in cognitive psychology, because they reflect a complex interplay of perception, attention and oculomotor control. A common insight of psychological research is that macro-movements are highly individual. Inspired by this finding, there has been a considerable amount of prior research on oculomotoric biometric identification. However, the accuracy of known approaches is too low and the time needed for identification is too long for any practical application. This thesis explores discriminative models for the task of biometric identification. Discriminative models optimize a quality measure of the predictions and are usually superior to generative approaches in discriminative tasks. However, using discriminative models requires to select a suitable form of data representation for sequential eye gaze data; i.e., by engineering features or constructing a sequence kernel and the performance of the classification model strongly depends on the data representation. We study two fundamentally different ways of representing eye gaze within a discriminative framework. In the first part of this thesis, we explore the integration of data and psychological background knowledge in the form of generative models to construct representations. To this end, we first develop generative statistical models of gaze behavior during reading and scene viewing that account for viewer-specific distributional properties of gaze patterns. In a second step, we develop a discriminative identification model by deriving Fisher kernel functions from these and several baseline models. We find that an SVM with Fisher kernel is able to reliably identify users based on their eye gaze during reading and scene viewing. However, since the generative models are constrained to use low-frequency macro-movements, they discard a significant amount of information contained in the raw eye tracking signal at a high cost: identification requires about one minute of input recording, which makes it inapplicable for real world biometric systems. In the second part of this thesis, we study a purely data-driven modeling approach. Here, we aim at automatically discovering the individual pattern hidden in the raw eye tracking signal. To this end, we develop a deep convolutional neural network DeepEyedentification that processes yaw and pitch gaze velocities and learns a representation end-to-end. Compared to prior work, this model increases the identification accuracy by one order of magnitude and the time to identification decreases to only seconds. The DeepEyedentificationLive model further improves upon the identification performance by processing binocular input and it also detects presentation-attacks. We find that by learning a representation, the performance of oculomotoric identification and presentation-attack detection can be driven close to practical relevance for biometric applications. Eye tracking devices with high sampling frequency and precision are expensive and the applicability of eye movement as a biometric feature heavily depends on cost of recording devices. In the last part of this thesis, we therefore study the requirements on data quality by evaluating the performance of the DeepEyedentificationLive network under reduced spatial and temporal resolution. We find that the method still attains a high identification accuracy at a temporal resolution of only 250 Hz and a precision of 0.03 degrees. Reducing both does not have an additive deteriorating effect. KW - Machine Learning Y1 - 2021 ER - TY - JOUR A1 - Gautam, Khem Raj A1 - Zhang, Guoqiang A1 - Landwehr, Niels A1 - Adolphs, Julian T1 - Machine learning for improvement of thermal conditions inside a hybrid ventilated animal building JF - Computers and electronics in agriculture : COMPAG online ; an international journal N2 - In buildings with hybrid ventilation, natural ventilation opening positions (windows), mechanical ventilation rates, heating, and cooling are manipulated to maintain desired thermal conditions. The indoor temperature is regulated solely by ventilation (natural and mechanical) when the external conditions are favorable to save external heating and cooling energy. The ventilation parameters are determined by a rule-based control scheme, which is not optimal. This study proposes a methodology to enable real-time optimum control of ventilation parameters. We developed offline prediction models to estimate future thermal conditions from the data collected from building in operation. The developed offline model is then used to find the optimal controllable ventilation parameters in real-time to minimize the setpoint deviation in the building. With the proposed methodology, the experimental building's setpoint deviation improved for 87% of time, on average, by 0.53 degrees C compared to the current deviations. KW - Animal building KW - Natural ventilation KW - Automatically controlled windows KW - Machine learning KW - Optimization Y1 - 2021 U6 - https://doi.org/10.1016/j.compag.2021.106259 SN - 0168-1699 SN - 1872-7107 VL - 187 PB - Elsevier Science CY - Amsterdam [u.a.] 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 - Combi, Carlo A1 - Oliboni, Barbara A1 - Weske, Mathias A1 - Zerbato, Francesca T1 - Seamless conceptual modeling of processes with transactional and analytical data JF - Data & knowledge engineering N2 - In the field of Business Process Management (BPM), modeling business processes and related data is a critical issue since process activities need to manage data stored in databases. The connection between processes and data is usually handled at the implementation level, even if modeling both processes and data at the conceptual level should help designers in improving business process models and identifying requirements for implementation. Especially in data -and decision-intensive contexts, business process activities need to access data stored both in databases and data warehouses. In this paper, we complete our approach for defining a novel conceptual view that bridges process activities and data. The proposed approach allows the designer to model the connection between business processes and database models and define the operations to perform, providing interesting insights on the overall connected perspective and hints for identifying activities that are crucial for decision support. KW - Conceptual modeling KW - Business process modeling KW - BPMN KW - Data modeling KW - Data warehouse KW - Decision support Y1 - 2021 U6 - https://doi.org/10.1016/j.datak.2021.101895 SN - 0169-023X SN - 1872-6933 VL - 134 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Körppen, Tim A1 - Ullrich, André A1 - Bertheau, Clementine T1 - Durchblick statt Bauchgefühl – Transformation zur Data-Driven Organization JF - Wirtschaftsinformatik & Management N2 - Um in der digitalisierten Wirtschaft mitzuspielen, müssen Unternehmen, Markt und insbesondere Kunden detailliert verstanden werden. Neben den „Big Playern“ aus dem Silicon Valley sieht der deutsche Mittelstand, der zu großen Teilen noch auf gewachsenen IT-Infrastrukturen und Prozessen agiert, oft alt aus. Um in den nächsten Jahren nicht gänzlich abgehängt zu werden, ist ein Umbruch notwendig. Sowohl Leistungserstellungsprozesse als auch Leistungsangebot müssen transparent und datenbasiert ausgerichtet werden. Nur so können Geschäftsvorfälle, das Marktgeschehen sowie Handeln der Akteure integrativ bewertet und fundierte Entscheidungen getroffen werden. In diesem Beitrag wird das Konzept der Data-Driven Organization vorgestellt und aufgezeigt, wie Unternehmen den eigenen Analyticsreifegrad ermitteln und in einem iterativen Transformationsprozess steigern können. Y1 - 2021 U6 - https://doi.org/10.1365/s35764-021-00370-7 SN - 1867-5905 VL - 13 IS - 6 SP - 452 EP - 459 PB - Springer Gabler CY - Wiesbaden ER - TY - JOUR A1 - Ullrich, André A1 - Teichmann, Malte A1 - Gronau, Norbert T1 - Fast trainable capabilities in software engineering-skill development in learning factories JF - Ji suan ji jiao yu = Computer Education / Qing hua da xue N2 - The increasing demand for software engineers cannot completely be fulfilled by university education and conventional training approaches due to limited capacities. Accordingly, an alternative approach is necessary where potential software engineers are being educated in software engineering skills using new methods. We suggest micro tasks combined with theoretical lessons to overcome existing skill deficits and acquire fast trainable capabilities. This paper addresses the gap between demand and supply of software engineers by introducing an actionoriented and scenario-based didactical approach, which enables non-computer scientists to code. Therein, the learning content is provided in small tasks and embedded in learning factory scenarios. Therefore, different requirements for software engineers from the market side and from an academic viewpoint are analyzed and synthesized into an integrated, yet condensed skills catalogue. This enables the development of training and education units that focus on the most important skills demanded on the market. To achieve this objective, individual learning scenarios are developed. Of course, proper basic skills in coding cannot be learned over night but software programming is also no sorcery. KW - learning factory KW - programming skills KW - software engineering KW - training Y1 - 2021 U6 - https://doi.org/10.16512/j.cnki.jsjjy.2020.12.002 SN - 1672-5913 IS - 12 SP - 2 EP - 10 PB - [Verlag nicht ermittelbar] CY - Bei jing shi ER - TY - JOUR A1 - Marx, Susanne A1 - Freundlich, Heidi A1 - Klotz, Michael A1 - Kylänen, Mika A1 - Niedoszytko, Grazyna A1 - Swacha, Jakub A1 - Vollerthum, Anne T1 - Towards an Online Learning Community on Digitalization in Tourism JF - EMOOCs 2021 N2 - Information technology and digital solutions as enablers in the tourism sector require continuous development of skills, as digital transformation is characterized by fast change, complexity and uncertainty. This research investigates how a cMOOC concept could support the tourism industry. A consortium of three universities, a tourism association, and a tourist attraction investigates online learning needs and habits of tourism industry stakeholders in the field of digitalization in a cross-border study in the Baltic Sea region. The multi-national survey (n = 244) reveals a high interest in participating in an online learning community, with two-thirds of respondents seeing opportunities to contributing to such community apart from consuming knowledge. The paper demonstrates preferred ways of learning, motivational and hampering aspects as well as types of possible contributions. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515986 SN - 978-3-86956-512-5 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - CHAP A1 - Abramova, Olga A1 - Gundlach, Jana A1 - Bilda, Juliane T1 - Understanding the role of newsfeed clutter in stereotype activation BT - the case of Facebook T2 - PACIS 2021 proceedings N2 - Despite the phenomenal growth of Big Data Analytics in the last few years, little research is done to explicate the relationship between Big Data Analytics Capability (BDAC) and indirect strategic value derived from such digital capabilities. We attempt to address this gap by proposing a conceptual model of the BDAC - Innovation relationship using dynamic capability theory. The work expands on BDAC business value research and extends the nominal research done on BDAC – innovation. We focus on BDAC's relationship with different innovation objects, namely product, business process, and business model innovation, impacting all value chain activities. The insights gained will stimulate academic and practitioner interest in explicating strategic value generated from BDAC and serve as a framework for future research on the subject Y1 - 2021 UR - https://aisel.aisnet.org/pacis2021/79 SN - 978-1-7336325-7-7 IS - 473 PB - AIS Electronic Library (AISeL) CY - [Erscheinungsort nicht ermittelbar] ER - TY - JOUR A1 - Cseh, Ágnes A1 - Juhos, Attila T1 - Pairwise preferences in the stable marriage problem JF - ACM Transactions on Economics and Computation / Association for Computing Machinery N2 - We study the classical, two-sided stable marriage problem under pairwise preferences. In the most general setting, agents are allowed to express their preferences as comparisons of any two of their edges, and they also have the right to declare a draw or even withdraw from such a comparison. This freedom is then gradually restricted as we specify six stages of orderedness in the preferences, ending with the classical case of strictly ordered lists. We study all cases occurring when combining the three known notions of stability-weak, strong, and super-stability-under the assumption that each side of the bipartite market obtains one of the six degrees of orderedness. By designing three polynomial algorithms and two NP-completeness proofs, we determine the complexity of all cases not yet known and thus give an exact boundary in terms of preference structure between tractable and intractable cases. KW - Stable marriage KW - intransitivity KW - acyclic preferences KW - poset KW - weakly KW - stable matching KW - strongly stable matching KW - super stable matching Y1 - 2021 U6 - https://doi.org/10.1145/3434427 SN - 2167-8375 SN - 2167-8383 VL - 9 IS - 1 PB - Association for Computing Machinery CY - New York ER - TY - JOUR A1 - Cseh, Ágnes A1 - Kavitha, Telikepalli T1 - Popular matchings in complete graphs JF - Algorithmica : an international journal in computer science N2 - Our input is a complete graph G on n vertices where each vertex has a strict ranking of all other vertices in G. The goal is to construct a matching in G that is popular. A matching M is popular if M does not lose a head-to-head election against any matching M ': here each vertex casts a vote for the matching in {M,M '} in which it gets a better assignment. Popular matchings need not exist in the given instance G and the popular matching problem is to decide whether one exists or not. The popular matching problem in G is easy to solve for odd n. Surprisingly, the problem becomes NP-complete for even n, as we show here. This is one of the few graph theoretic problems efficiently solvable when n has one parity and NP-complete when n has the other parity. KW - Popular matching KW - Complexity KW - Stable matching Y1 - 2021 U6 - https://doi.org/10.1007/s00453-020-00791-7 SN - 0178-4617 SN - 1432-0541 VL - 83 IS - 5 SP - 1493 EP - 1523 PB - Springer CY - New York ER - TY - JOUR A1 - Brede, Nuria A1 - Botta, Nicola T1 - On the correctness of monadic backward induction JF - Journal of functional programming N2 - In control theory, to solve a finite-horizon sequential decision problem (SDP) commonly means to find a list of decision rules that result in an optimal expected total reward (or cost) when taking a given number of decision steps. SDPs are routinely solved using Bellman's backward induction. Textbook authors (e.g. Bertsekas or Puterman) typically give more or less formal proofs to show that the backward induction algorithm is correct as solution method for deterministic and stochastic SDPs. Botta, Jansson and Ionescu propose a generic framework for finite horizon, monadic SDPs together with a monadic version of backward induction for solving such SDPs. In monadic SDPs, the monad captures a generic notion of uncertainty, while a generic measure function aggregates rewards. In the present paper, we define a notion of correctness for monadic SDPs and identify three conditions that allow us to prove a correctness result for monadic backward induction that is comparable to textbook correctness proofs for ordinary backward induction. The conditions that we impose are fairly general and can be cast in category-theoretical terms using the notion of Eilenberg-Moore algebra. They hold in familiar settings like those of deterministic or stochastic SDPs, but we also give examples in which they fail. Our results show that backward induction can safely be employed for a broader class of SDPs than usually treated in textbooks. However, they also rule out certain instances that were considered admissible in the context of Botta et al. 's generic framework. Our development is formalised in Idris as an extension of the Botta et al. framework and the sources are available as supplementary material. Y1 - 2021 U6 - https://doi.org/10.1017/S0956796821000228 SN - 1469-7653 SN - 0956-7968 VL - 31 PB - Cambridge University Press CY - Cambridge ER - TY - JOUR A1 - Benson, Lawrence A1 - Makait, Hendrik A1 - Rabl, Tilmann T1 - Viper BT - An Efficient Hybrid PMem-DRAM Key-Value Store JF - Proceedings of the VLDB Endowment N2 - Key-value stores (KVSs) have found wide application in modern software systems. For persistence, their data resides in slow secondary storage, which requires KVSs to employ various techniques to increase their read and write performance from and to the underlying medium. Emerging persistent memory (PMem) technologies offer data persistence at close-to-DRAM speed, making them a promising alternative to classical disk-based storage. However, simply drop-in replacing existing storage with PMem does not yield good results, as block-based access behaves differently in PMem than on disk and ignores PMem's byte addressability, layout, and unique performance characteristics. In this paper, we propose three PMem-specific access patterns and implement them in a hybrid PMem-DRAM KVS called Viper. We employ a DRAM-based hash index and a PMem-aware storage layout to utilize the random-write speed of DRAM and efficient sequential-write performance PMem. Our evaluation shows that Viper significantly outperforms existing KVSs for core KVS operations while providing full data persistence. Moreover, Viper outperforms existing PMem-only, hybrid, and disk-based KVSs by 4-18x for write workloads, while matching or surpassing their get performance. KW - memory Y1 - 2021 U6 - https://doi.org/10.14778/3461535.3461543 SN - 2150-8097 VL - 14 IS - 9 SP - 1544 EP - 1556 PB - Association for Computing Machinery CY - New York ER - TY - CHAP A1 - Krause, Hannes-Vincent A1 - Baumann, Annika T1 - The devil in disguise BT - malicious envy’s impact on harmful interactions between social networking site users T2 - ICIS 2021: user behaviors, engagement, and consequences N2 - Envy constitutes a serious issue on Social Networking Sites (SNSs), as this painful emotion can severely diminish individuals' well-being. With prior research mainly focusing on the affective consequences of envy in the SNS context, its behavioral consequences remain puzzling. While negative interactions among SNS users are an alarming issue, it remains unclear to which extent the harmful emotion of malicious envy contributes to these toxic dynamics. This study constitutes a first step in understanding malicious envy’s causal impact on negative interactions within the SNS sphere. Within an online experiment, we experimentally induce malicious envy and measure its immediate impact on users’ negative behavior towards other users. Our findings show that malicious envy seems to be an essential factor fueling negativity among SNS users and further illustrate that this effect is especially pronounced when users are provided an objective factor to mask their envy and justify their norm-violating negative behavior. Y1 - 2021 UR - https://aisel.aisnet.org/icis2021/user_behaivors/user_behaivors/21 PB - AIS Electronic Library (AISeL) CY - [Erscheinungsort nicht ermittelbar] ER - TY - JOUR A1 - Xu, Rudan A1 - Razaghi-Moghadam, Zahra A1 - Nikoloski, Zoran T1 - Maximization of non-idle enzymes improves the coverage of the estimated maximal in vivo enzyme catalytic rates in Escherichia coli JF - Bioinformatics N2 - Motivation: Constraint-based modeling approaches allow the estimation of maximal in vivo enzyme catalytic rates that can serve as proxies for enzyme turnover numbers. Yet, genome-scale flux profiling remains a challenge in deploying these approaches to catalogue proxies for enzyme catalytic rates across organisms. Results: Here, we formulate a constraint-based approach, termed NIDLE-flux, to estimate fluxes at a genome-scale level by using the principle of efficient usage of expressed enzymes. Using proteomics data from Escherichia coli, we show that the fluxes estimated by NIDLE-flux and the existing approaches are in excellent qualitative agreement (Pearson correlation > 0.9). We also find that the maximal in vivo catalytic rates estimated by NIDLE-flux exhibits a Pearson correlation of 0.74 with in vitro enzyme turnover numbers. However, NIDLE-flux results in a 1.4-fold increase in the size of the estimated maximal in vivo catalytic rates in comparison to the contenders. Integration of the maximum in vivo catalytic rates with publically available proteomics and metabolomics data provide a better match to fluxes estimated by NIDLE-flux. Therefore, NIDLE-flux facilitates more effective usage of proteomics data to estimate proxies for kcatomes. Y1 - 2021 U6 - https://doi.org/10.1093/bioinformatics/btab575 SN - 1367-4803 SN - 1460-2059 VL - 37 IS - 21 SP - 3848 EP - 3855 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Angeleska, Angela A1 - Omranian, Sara A1 - Nikoloski, Zoran T1 - Coherent network partitions BT - Characterizations with cographs and prime graphs JF - Theoretical computer science : the journal of the EATCS N2 - We continue to study coherent partitions of graphs whereby the vertex set is partitioned into subsets that induce biclique spanned subgraphs. The problem of identifying the minimum number of edges to obtain biclique spanned connected components (CNP), called the coherence number, is NP-hard even on bipartite graphs. Here, we propose a graph transformation geared towards obtaining an O (log n)-approximation algorithm for the CNP on a bipartite graph with n vertices. The transformation is inspired by a new characterization of biclique spanned subgraphs. In addition, we study coherent partitions on prime graphs, and show that finding coherent partitions reduces to the problem of finding coherent partitions in a prime graph. Therefore, these results provide future directions for approximation algorithms for the coherence number of a given graph. KW - Graph partitions KW - Network clustering KW - Cographs KW - Coherent partition KW - Prime graphs Y1 - 2021 U6 - https://doi.org/10.1016/j.tcs.2021.10.002 SN - 0304-3975 VL - 894 SP - 3 EP - 11 PB - Elsevier CY - Amsterdam [u.a.] ER -