@misc{BoissierKurzynski2018, author = {Boissier, Martin and Kurzynski, Daniel}, title = {Workload-Driven Horizontal Partitioning and Pruning for Large HTAP Systems}, series = {2018 IEEE 34th International Conference on Data Engineering Workshops (ICDEW)}, journal = {2018 IEEE 34th International Conference on Data Engineering Workshops (ICDEW)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-6306-6}, doi = {10.1109/ICDEW.2018.00026}, pages = {116 -- 121}, year = {2018}, abstract = {Modern server systems with large NUMA architectures necessitate (i) data being distributed over the available computing nodes and (ii) NUMA-aware query processing to enable effective parallel processing in database systems. As these architectures incur significant latency and throughout penalties for accessing non-local data, queries should be executed as close as possible to the data. To further increase both performance and efficiency, data that is not relevant for the query result should be skipped as early as possible. One way to achieve this goal is horizontal partitioning to improve static partition pruning. As part of our ongoing work on workload-driven partitioning, we have implemented a recent approach called aggressive data skipping and extended it to handle both analytical as well as transactional access patterns. In this paper, we evaluate this approach with the workload and data of a production enterprise system of a Global 2000 company. The results show that over 80\% of all tuples can be skipped in average while the resulting partitioning schemata are surprisingly stable over time.}, language = {en} } @misc{HalfpapSchlosser2019, author = {Halfpap, Stefan and Schlosser, Rainer}, title = {Workload-Driven Fragment Allocation for Partially Replicated Databases Using Linear Programming}, series = {2019 IEEE 35th International Conference on Data Engineering (ICDE)}, journal = {2019 IEEE 35th International Conference on Data Engineering (ICDE)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-7474-1}, issn = {1084-4627}, doi = {10.1109/ICDE.2019.00188}, pages = {1746 -- 1749}, year = {2019}, abstract = {In replication schemes, replica nodes can process read-only queries on snapshots of the master node without violating transactional consistency. By analyzing the workload, we can identify query access patterns and replicate data depending to its access frequency. In this paper, we define a linear programming (LP) model to calculate the set of partial replicas with the lowest overall memory capacity while evenly balancing the query load. Furthermore, we propose a scalable decomposition heuristic to calculate solutions for larger problem sizes. While guaranteeing the same performance as state-of-the-art heuristics, our decomposition approach calculates allocations with up to 23\% lower memory footprint for the TPC-H benchmark.}, language = {en} } @misc{TeusnerMatthiesStaubitz2018, author = {Teusner, Ralf and Matthies, Christoph and Staubitz, Thomas}, title = {What Stays in Mind?}, series = {IEEE Frontiers in Education Conference (FIE)}, journal = {IEEE Frontiers in Education Conference (FIE)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-1174-6}, issn = {0190-5848}, doi = {10.1109/FIE.2018.8658890}, pages = {9}, year = {2018}, language = {en} } @misc{AndjelkovicBabicLietal.2019, author = {Andjelkovic, Marko and Babic, Milan and Li, Yuanqing and Schrape, Oliver and Krstić, Miloš and Kraemer, Rolf}, title = {Use of decoupling cells for mitigation of SET effects in CMOS combinational gates}, series = {2018 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS)}, journal = {2018 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-9562-3}, doi = {10.1109/ICECS.2018.8617996}, pages = {361 -- 364}, year = {2019}, abstract = {This paper investigates the applicability of CMOS decoupling cells for mitigating the Single Event Transient (SET) effects in standard combinational gates. The concept is based on the insertion of two decoupling cells between the gate's output and the power/ground terminals. To verify the proposed hardening approach, extensive SPICE simulations have been performed with standard combinational cells designed in IHP's 130 nm bulk CMOS technology. Obtained simulation results have shown that the insertion of decoupling cells results in the increase of the gate's critical charge, thus reducing the gate's soft error rate (SER). Moreover, the decoupling cells facilitate the suppression of SET pulses propagating through the gate. It has been shown that the decoupling cells may be a competitive alternative to gate upsizing and gate duplication for hardening the gates with lower critical charge and multiple (3 or 4) inputs, as well as for filtering the short SET pulses induced by low-LET particles.}, language = {en} } @misc{SukmanaTorkuraChengetal.2018, author = {Sukmana, Muhammad Ihsan Haikal and Torkura, Kennedy A. and Cheng, Feng and Meinel, Christoph and Graupner, Hendrik}, title = {Unified logging system for monitoring multiple cloud storage providers in cloud storage broker}, series = {32ND International Conference on Information Networking (ICOIN)}, journal = {32ND International Conference on Information Networking (ICOIN)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-2290-2}, doi = {10.1109/ICOIN.2018.8343081}, pages = {44 -- 49}, year = {2018}, abstract = {With the increasing demand for personal and enterprise data storage service, Cloud Storage Broker (CSB) provides cloud storage service using multiple Cloud Service Providers (CSPs) with guaranteed Quality of Service (QoS), such as data availability and security. However monitoring cloud storage usage in multiple CSPs has become a challenge for CSB due to lack of standardized logging format for cloud services that causes each CSP to implement its own format. In this paper we propose a unified logging system that can be used by CSB to monitor cloud storage usage across multiple CSPs. We gather cloud storage log files from three different CSPs and normalise these into our proposed log format that can be used for further analysis process. We show that our work enables a coherent view suitable for data navigation, monitoring, and analytics.}, language = {en} } @misc{KovacsIonLopesetal.2019, author = {Kovacs, Robert and Ion, Alexandra and Lopes, Pedro and Oesterreich, Tim and Filter, Johannes and Otto, Philip and Arndt, Tobias and Ring, Nico and Witte, Melvin and Synytsia, Anton and Baudisch, Patrick}, title = {TrussFormer}, series = {The 31st Annual ACM Symposium on User Interface Software and Technology}, journal = {The 31st Annual ACM Symposium on User Interface Software and Technology}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-5971-9}, doi = {10.1145/3290607.3311766}, pages = {1}, year = {2019}, abstract = {We present TrussFormer, an integrated end-to-end system that allows users to 3D print large-scale kinetic structures, i.e., structures that involve motion and deal with dynamic forces. TrussFormer builds on TrussFab, from which it inherits the ability to create static large-scale truss structures from 3D printed connectors and PET bottles. TrussFormer adds movement to these structures by placing linear actuators into them: either manually, wrapped in reusable components called assets, or by demonstrating the intended movement. TrussFormer verifies that the resulting structure is mechanically sound and will withstand the dynamic forces resulting from the motion. To fabricate the design, TrussFormer generates the underlying hinge system that can be printed on standard desktop 3D printers. We demonstrate TrussFormer with several example objects, including a 6-legged walking robot and a 4m-tall animatronics dinosaur with 5 degrees of freedom.}, language = {en} } @misc{KovacsIonLopesetal.2018, author = {Kovacs, Robert and Ion, Alexandra and Lopes, Pedro and Oesterreich, Tim and Filter, Johannes and Otto, Philip and Arndt, Tobias and Ring, Nico and Witte, Melvin and Synytsia, Anton and Baudisch, Patrick}, title = {TrussFormer}, series = {UIST '18: Proceedings of the 31st Annual ACM Symposium on User Interface Software and Technology}, journal = {UIST '18: Proceedings of the 31st Annual ACM Symposium on User Interface Software and Technology}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-5948-1}, doi = {10.1145/3242587.3242607}, pages = {113 -- 125}, year = {2018}, abstract = {We present TrussFormer, an integrated end-to-end system that allows users to 3D print large-scale kinetic structures, i.e., structures that involve motion and deal with dynamic forces. TrussFormer builds on TrussFab, from which it inherits the ability to create static large-scale truss structures from 3D printed connectors and PET bottles. TrussFormer adds movement to these structures by placing linear actuators into them: either manually, wrapped in reusable components called assets, or by demonstrating the intended movement. TrussFormer verifies that the resulting structure is mechanically sound and will withstand the dynamic forces resulting from the motion. To fabricate the design, TrussFormer generates the underlying hinge system that can be printed on standard desktop 3D printers. We demonstrate TrussFormer with several example objects, including a 6-legged walking robot and a 4m-tall animatronics dinosaur with 5 degrees of freedom.}, language = {en} } @misc{PlauthPolze2018, author = {Plauth, Max and Polze, Andreas}, title = {Towards improving data transfer efficiency for accelerators using hardware compression}, series = {Sixth International Symposium on Computing and Networking Workshops (CANDARW)}, journal = {Sixth International Symposium on Computing and Networking Workshops (CANDARW)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-9184-7}, doi = {10.1109/CANDARW.2018.00031}, pages = {125 -- 131}, year = {2018}, abstract = {The overhead of moving data is the major limiting factor in todays hardware, especially in heterogeneous systems where data needs to be transferred frequently between host and accelerator memory. With the increasing availability of hardware-based compression facilities in modern computer architectures, this paper investigates the potential of hardware-accelerated I/O Link Compression as a promising approach to reduce data volumes and transfer time, thus improving the overall efficiency of accelerators in heterogeneous systems. Our considerations are focused on On-the-Fly compression in both Single-Node and Scale-Out deployments. Based on a theoretical analysis, this paper demonstrates the feasibility of hardware-accelerated On-the-Fly I/O Link Compression for many workloads in a Scale-Out scenario, and for some even in a Single-Node scenario. These findings are confirmed in a preliminary evaluation using software-and hardware-based implementations of the 842 compression algorithm.}, language = {en} } @misc{BrandGiese2019, author = {Brand, Thomas and Giese, Holger Burkhard}, title = {Towards Generic Adaptive Monitoring}, series = {2018 IEEE 12th International Conference on Self-Adaptive and Self-Organizing Systems (SASO)}, journal = {2018 IEEE 12th International Conference on Self-Adaptive and Self-Organizing Systems (SASO)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-5172-8}, issn = {1949-3673}, doi = {10.1109/SASO.2018.00027}, pages = {156 -- 161}, year = {2019}, abstract = {Monitoring is a key prerequisite for self-adaptive software and many other forms of operating software. Monitoring relevant lower level phenomena like the occurrences of exceptions and diagnosis data requires to carefully examine which detailed information is really necessary and feasible to monitor. Adaptive monitoring permits observing a greater variety of details with less overhead, if most of the time the MAPE-K loop can operate using only a small subset of all those details. However, engineering such an adaptive monitoring is a major engineering effort on its own that further complicates the development of self-adaptive software. The proposed approach overcomes the outlined problems by providing generic adaptive monitoring via runtime models. It reduces the effort to introduce and apply adaptive monitoring by avoiding additional development effort for controlling the monitoring adaptation. Although the generic approach is independent from the monitoring purpose, it still allows for substantial savings regarding the monitoring resource consumption as demonstrated by an example.}, language = {en} } @misc{RenzMeinel2019, author = {Renz, Jan and Meinel, Christoph}, title = {The "Bachelor Project"}, series = {2019 IEEE Global Engineering Education Conference (EDUCON)}, journal = {2019 IEEE Global Engineering Education Conference (EDUCON)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-9506-7}, issn = {2165-9567}, doi = {10.1109/EDUCON.2019.8725140}, pages = {580 -- 587}, year = {2019}, abstract = {One of the challenges of educating the next generation of computer scientists is to teach them to become team players, that are able to communicate and interact not only with different IT systems, but also with coworkers and customers with a non-it background. The "bachelor project" is a project based on team work and a close collaboration with selected industry partners. The authors hosted some of the teams since spring term 2014/15. In the paper at hand we explain and discuss this concept and evaluate its success based on students' evaluation and reports. Furthermore, the technology-stack that has been used by the teams is evaluated to understand how self-organized students in IT-related projects work. We will show that and why the bachelor is the most successful educational format in the perception of the students and how this positive results can be improved by the mentors.}, language = {en} } @misc{TeichmannUllrichGronau2019, author = {Teichmann, Malte and Ullrich, Andre and Gronau, Norbert}, title = {Subject-oriented learning}, series = {Procedia Manufacturing}, volume = {31}, journal = {Procedia Manufacturing}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2351-9789}, doi = {10.1016/j.promfg.2019.03.012}, pages = {72 -- 78}, year = {2019}, abstract = {The transformation to a digitized company changes not only the work but also social context for the employees and requires inter alia new knowledge and skills from them. Additionally, individual action problems arise. This contribution proposes the subject-oriented learning theory, in which the employees´ action problems are the starting point of training activities in learning factories. In this contribution, the subject-oriented learning theory is exemplified and respective advantages for vocational training in learning factories are pointed out both theoretically and practically. Thereby, especially the individual action problems of learners and the infrastructure are emphasized as starting point for learning processes and competence development.}, language = {en} } @misc{WelearegaiSchlueterHammer2019, author = {Welearegai, Gebrehiwet B. and Schlueter, Max and Hammer, Christian}, title = {Static security evaluation of an industrial web application}, series = {Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing}, journal = {Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-5933-7}, doi = {10.1145/3297280.3297471}, pages = {1952 -- 1961}, year = {2019}, abstract = {JavaScript is the most popular programming language for web applications. Static analysis of JavaScript applications is highly challenging due to its dynamic language constructs and event-driven asynchronous executions, which also give rise to many security-related bugs. Several static analysis tools to detect such bugs exist, however, research has not yet reported much on the precision and scalability trade-off of these analyzers. As a further obstacle, JavaScript programs structured in Node. js modules need to be collected for analysis, but existing bundlers are either specific to their respective analysis tools or not particularly suitable for static analysis.}, language = {en} } @misc{KayemMeinelWolthusen2018, author = {Kayem, Anne Voluntas dei Massah and Meinel, Christoph and Wolthusen, Stephen D.}, title = {Smart micro-grid systems security and privacy preface}, series = {Smart micro-grid systems security and privacy}, volume = {71}, journal = {Smart micro-grid systems security and privacy}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-3-319-91427-5}, doi = {10.1007/978-3-319-91427-5_1}, pages = {VII -- VIII}, year = {2018}, abstract = {Studies indicate that reliable access to power is an important enabler for economic growth. To this end, modern energy management systems have seen a shift from reliance on time-consuming manual procedures , to highly automated management , with current energy provisioning systems being run as cyber-physical systems . Operating energy grids as a cyber-physical system offers the advantage of increased reliability and dependability , but also raises issues of security and privacy. In this chapter, we provide an overview of the contents of this book showing the interrelation between the topics of the chapters in terms of smart energy provisioning. We begin by discussing the concept of smart-grids in general, proceeding to narrow our focus to smart micro-grids in particular. Lossy networks also provide an interesting framework for enabling the implementation of smart micro-grids in remote/rural areas, where deploying standard smart grids is economically and structurally infeasible. To this end, we consider an architectural design for a smart micro-grid suited to low-processing capable devices. We model malicious behaviour, and propose mitigation measures based properties to distinguish normal from malicious behaviour .}, language = {en} } @misc{FrickeDoellnerAsche2018, author = {Fricke, Andreas and D{\"o}llner, J{\"u}rgen Roland Friedrich and Asche, Hartmut}, title = {Servicification - Trend or Paradigm Shift in Geospatial Data Processing?}, series = {Computational Science and Its Applications - ICCSA 2018, PT III}, volume = {10962}, journal = {Computational Science and Its Applications - ICCSA 2018, PT III}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-95168-3}, issn = {0302-9743}, doi = {10.1007/978-3-319-95168-3_23}, pages = {339 -- 350}, year = {2018}, abstract = {Currently we are witnessing profound changes in the geospatial domain. Driven by recent ICT developments, such as web services, serviceoriented computing or open-source software, an explosion of geodata and geospatial applications or rapidly growing communities of non-specialist users, the crucial issue is the provision and integration of geospatial intelligence in these rapidly changing, heterogeneous developments. This paper introduces the concept of Servicification into geospatial data processing. Its core idea is the provision of expertise through a flexible number of web-based software service modules. Selection and linkage of these services to user profiles, application tasks, data resources, or additional software allow for the compilation of flexible, time-sensitive geospatial data handling processes. Encapsulated in a string of discrete services, the approach presented here aims to provide non-specialist users with geospatial expertise required for the effective, professional solution of a defined application problem. Providing users with geospatial intelligence in the form of web-based, modular services, is a completely different approach to geospatial data processing. This novel concept puts geospatial intelligence, made available through services encapsulating rule bases and algorithms, in the centre and at the disposal of the users, regardless of their expertise.}, language = {en} } @misc{BartzYangMeinel2018, author = {Bartz, Christian and Yang, Haojin and Meinel, Christoph}, title = {SEE: Towards semi-supervised end-to-end scene text recognition}, series = {Proceedings of the Thirty-Second AAAI Conference on Artificial Intelligence, Thirtieth Innovative Applications of Artificial Intelligence Conference, Eight Symposium on Educational Advances in Artificial Intelligence}, volume = {10}, journal = {Proceedings of the Thirty-Second AAAI Conference on Artificial Intelligence, Thirtieth Innovative Applications of Artificial Intelligence Conference, Eight Symposium on Educational Advances in Artificial Intelligence}, publisher = {ASSOC Association for the Advancement of Artificial Intelligence}, address = {Palo Alto}, isbn = {978-1-57735-800-8}, pages = {6674 -- 6681}, year = {2018}, abstract = {Detecting and recognizing text in natural scene images is a challenging, yet not completely solved task. In recent years several new systems that try to solve at least one of the two sub-tasks (text detection and text recognition) have been proposed. In this paper we present SEE, a step towards semi-supervised neural networks for scene text detection and recognition, that can be optimized end-to-end. Most existing works consist of multiple deep neural networks and several pre-processing steps. In contrast to this, we propose to use a single deep neural network, that learns to detect and recognize text from natural images, in a semi-supervised way. SEE is a network that integrates and jointly learns a spatial transformer network, which can learn to detect text regions in an image, and a text recognition network that takes the identified text regions and recognizes their textual content. We introduce the idea behind our novel approach and show its feasibility, by performing a range of experiments on standard benchmark datasets, where we achieve competitive results.}, language = {en} } @misc{TorkuraSukmanaMeinigetal.2018, author = {Torkura, Kennedy A. and Sukmana, Muhammad Ihsan Haikal and Meinig, Michael and Kayem, Anne V. D. M. and Cheng, Feng and Meinel, Christoph and Graupner, Hendrik}, title = {Securing cloud storage brokerage systems through threat models}, series = {Proceedings IEEE 32nd International Conference on Advanced Information Networking and Applications (AINA)}, journal = {Proceedings IEEE 32nd International Conference on Advanced Information Networking and Applications (AINA)}, publisher = {IEEE}, address = {New York}, isbn = {978-1-5386-2195-0}, issn = {1550-445X}, doi = {10.1109/AINA.2018.00114}, pages = {759 -- 768}, year = {2018}, abstract = {Cloud storage brokerage is an abstraction aimed at providing value-added services. However, Cloud Service Brokers are challenged by several security issues including enlarged attack surfaces due to integration of disparate components and API interoperability issues. Therefore, appropriate security risk assessment methods are required to identify and evaluate these security issues, and examine the efficiency of countermeasures. A possible approach for satisfying these requirements is employment of threat modeling concepts, which have been successfully applied in traditional paradigms. In this work, we employ threat models including attack trees, attack graphs and Data Flow Diagrams against a Cloud Service Broker (CloudRAID) and analyze these security threats and risks. Furthermore, we propose an innovative technique for combining Common Vulnerability Scoring System (CVSS) and Common Configuration Scoring System (CCSS) base scores in probabilistic attack graphs to cater for configuration-based vulnerabilities which are typically leveraged for attacking cloud storage systems. This approach is necessary since existing schemes do not provide sufficient security metrics, which are imperatives for comprehensive risk assessments. We demonstrate the efficiency of our proposal by devising CCSS base scores for two common attacks against cloud storage: Cloud Storage Enumeration Attack and Cloud Storage Exploitation Attack. These metrics are then used in Attack Graph Metric-based risk assessment. Our experimental evaluation shows that our approach caters for the aforementioned gaps and provides efficient security hardening options. Therefore, our proposals can be employed to improve cloud security.}, language = {en} } @misc{ChakrabortyHammerBugiel2019, author = {Chakraborty, Dhiman and Hammer, Christian and Bugiel, Sven}, title = {Secure Multi-Execution in Android}, series = {Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing}, journal = {Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing}, publisher = {Association for Computing Machinery}, address = {New York}, isbn = {978-1-4503-5933-7}, doi = {10.1145/3297280.3297469}, pages = {1934 -- 1943}, year = {2019}, abstract = {Mobile operating systems, such as Google's Android, have become a fixed part of our daily lives and are entrusted with a plethora of private information. Congruously, their data protection mechanisms have been improved steadily over the last decade and, in particular, for Android, the research community has explored various enhancements and extensions to the access control model. However, the vast majority of those solutions has been concerned with controlling the access to data, but equally important is the question of how to control the flow of data once released. Ignoring control over the dissemination of data between applications or between components of the same app, opens the door for attacks, such as permission re-delegation or privacy-violating third-party libraries. Controlling information flows is a long-standing problem, and one of the most recent and practical-oriented approaches to information flow control is secure multi-execution. In this paper, we present Ariel, the design and implementation of an IFC architecture for Android based on the secure multi-execution of apps. Ariel demonstrably extends Android's system with support for executing multiple instances of apps, and it is equipped with a policy lattice derived from the protection levels of Android's permissions as well as an I/O scheduler to achieve control over data flows between application instances. We demonstrate how secure multi-execution with Ariel can help to mitigate two prominent attacks on Android, permission re-delegations and malicious advertisement libraries.}, language = {en} } @misc{Matthies2018, author = {Matthies, Christoph}, title = {Scrum2kanban}, series = {Proceedings of the 2nd International Workshop on Software Engineering Education for Millennials}, journal = {Proceedings of the 2nd International Workshop on Software Engineering Education for Millennials}, publisher = {IEEE}, address = {New York}, isbn = {978-1-45035-750-0}, doi = {10.1145/3194779.3194784}, pages = {48 -- 55}, year = {2018}, abstract = {Using university capstone courses to teach agile software development methodologies has become commonplace, as agile methods have gained support in professional software development. This usually means students are introduced to and work with the currently most popular agile methodology: Scrum. However, as the agile methods employed in the industry change and are adapted to different contexts, university courses must follow suit. A prime example of this is the Kanban method, which has recently gathered attention in the industry. In this paper, we describe a capstone course design, which adds the hands-on learning of the lean principles advocated by Kanban into a capstone project run with Scrum. This both ensures that students are aware of recent process frameworks and ideas as well as gain a more thorough overview of how agile methods can be employed in practice. We describe the details of the course and analyze the participating students' perceptions as well as our observations. We analyze the development artifacts, created by students during the course in respect to the two different development methodologies. We further present a summary of the lessons learned as well as recommendations for future similar courses. The survey conducted at the end of the course revealed an overwhelmingly positive attitude of students towards the integration of Kanban into the course.}, language = {en} } @misc{HorowitzFeiRamosetal.2018, author = {Horowitz, Carol R. and Fei, Kezhen and Ramos, Michelle A. and Hauser, Diane and Ellis, Stephen B. and Calman, Neil and B{\"o}ttinger, Erwin}, title = {Receipt of genetic risk information significantly improves blood pressure control among African anecestry adults with hypertension}, series = {Journal of General Internal Medicine}, volume = {33}, journal = {Journal of General Internal Medicine}, publisher = {Springer}, address = {New York}, issn = {0884-8734}, doi = {10.1007/s11606-018-4413-y}, pages = {S322 -- S323}, year = {2018}, language = {en} } @misc{AlvianoRomeroDavilaSchaub2018, author = {Alviano, Mario and Romero Davila, Javier and Schaub, Torsten H.}, title = {Preference Relations by Approximation}, series = {Sixteenth International Conference on Principles of Knowledge Representation and Reasoning}, journal = {Sixteenth International Conference on Principles of Knowledge Representation and Reasoning}, publisher = {AAAI Conference on Artificial Intelligence}, address = {Palo Alto}, pages = {2 -- 11}, year = {2018}, abstract = {Declarative languages for knowledge representation and reasoning provide constructs to define preference relations over the set of possible interpretations, so that preferred models represent optimal solutions of the encoded problem. We introduce the notion of approximation for replacing preference relations with stronger preference relations, that is, relations comparing more pairs of interpretations. Our aim is to accelerate the computation of a non-empty subset of the optimal solutions by means of highly specialized algorithms. We implement our approach in Answer Set Programming (ASP), where problems involving quantitative and qualitative preference relations can be addressed by ASPRIN, implementing a generic optimization algorithm. Unlike this, chains of approximations allow us to reduce several preference relations to the preference relations associated with ASP's native weak constraints and heuristic directives. In this way, ASPRIN can now take advantage of several highly optimized algorithms implemented by ASP solvers for computing optimal solutions}, language = {en} }