TY - JOUR A1 - Cabalar, Pedro A1 - Fandinno, Jorge A1 - Schaub, Torsten H. A1 - Schellhorn, Sebastian T1 - Gelfond-Zhang aggregates as propositional formulas JF - Artificial intelligence N2 - Answer Set Programming (ASP) has become a popular and widespread paradigm for practical Knowledge Representation thanks to its expressiveness and the available enhancements of its input language. One of such enhancements is the use of aggregates, for which different semantic proposals have been made. In this paper, we show that any ASP aggregate interpreted under Gelfond and Zhang's (GZ) semantics can be replaced (under strong equivalence) by a propositional formula. Restricted to the original GZ syntax, the resulting formula is reducible to a disjunction of conjunctions of literals but the formulation is still applicable even when the syntax is extended to allow for arbitrary formulas (including nested aggregates) in the condition. Once GZ-aggregates are represented as formulas, we establish a formal comparison (in terms of the logic of Here-and-There) to Ferraris' (F) aggregates, which are defined by a different formula translation involving nested implications. In particular, we prove that if we replace an F-aggregate by a GZ-aggregate in a rule head, we do not lose answer sets (although more can be gained). This extends the previously known result that the opposite happens in rule bodies, i.e., replacing a GZ-aggregate by an F-aggregate in the body may yield more answer sets. Finally, we characterize a class of aggregates for which GZ- and F-semantics coincide. KW - Aggregates KW - Answer Set Programming Y1 - 2019 U6 - https://doi.org/10.1016/j.artint.2018.10.007 SN - 0004-3702 SN - 1872-7921 VL - 274 SP - 26 EP - 43 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Janhunen, Tomi A1 - Kaminski, Roland A1 - Ostrowski, Max A1 - Schellhorn, Sebastian A1 - Wanko, Philipp A1 - Schaub, Torsten H. T1 - Clingo goes linear constraints over reals and integers JF - Theory and practice of logic programming N2 - The recent series 5 of the Answer Set Programming (ASP) system clingo provides generic means to enhance basic ASP with theory reasoning capabilities. We instantiate this framework with different forms of linear constraints and elaborate upon its formal properties. Given this, we discuss the respective implementations, and present techniques for using these constraints in a reactive context. More precisely, we introduce extensions to clingo with difference and linear constraints over integers and reals, respectively, and realize them in complementary ways. Finally, we empirically evaluate the resulting clingo derivatives clingo[dl] and clingo[lp] on common language fragments and contrast them to related ASP systems. KW - Constraint Answer Set Programming (CASP) KW - Answer Set Programming (ASP) KW - Constraint Processing (CP) KW - Theory Solving Y1 - 2017 U6 - https://doi.org/10.1017/S1471068417000242 SN - 1471-0684 SN - 1475-3081 VL - 17 SP - 872 EP - 888 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Sarsakov, Vladimir A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - A compiler for nested logic programming Y1 - 2004 SN - 3-540- 20721-x ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - On Computing belief change operations using quantifield boolean formulas N2 - In this paper, we show how an approach to belief revision and belief contraction can be axiomatized by means of quantified Boolean formulas. Specifically, we consider the approach of belief change scenarios, a general framework that has been introduced for expressing different forms of belief change. The essential idea is that for a belief change scenario (K, R, C), the set of formulas K, representing the knowledge base, is modified so that the sets of formulas R and C are respectively true in, and consistent with the result. By restricting the form of a belief change scenario, one obtains specific belief change operators including belief revision, contraction, update, and merging. For both the general approach and for specific operators, we give a quantified Boolean formula such that satisfying truth assignments to the free variables correspond to belief change extensions in the original approach. Hence, we reduce the problem of determining the results of a belief change operation to that of satisfiability. This approach has several benefits. First, it furnishes an axiomatic specification of belief change with respect to belief change scenarios. This then leads to further insight into the belief change framework. Second, this axiomatization allows us to identify strict complexity bounds for the considered reasoning tasks. Third, we have implemented these different forms of belief change by means of existing solvers for quantified Boolean formulas. As well, it appears that this approach may be straightforwardly applied to other specific approaches to belief change Y1 - 2004 SN - 0955-792X ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - On computing solutions to belief change scenarios Y1 - 2001 SN - 3-540- 42464-4 ER - TY - JOUR A1 - Pearce, David A1 - Sarsakov, Vladimir A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - A polynomial translation of logic programs with nested expressions into disjunctive logic programs Y1 - 2002 SN - 3-540-43930-7 ER - TY - JOUR A1 - Besnard, Philippe A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - Paraconsistent reasoning via quantified boolean formulas Y1 - 2002 SN - 3-540-44190-5 ER - TY - JOUR A1 - Brain, Martin A1 - Gebser, Martin A1 - Pührer, Jörg A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - "That is illogical, Captain!" : the debugging support tool spock for answer-set programs ; system description Y1 - 2007 ER - TY - JOUR A1 - Pearce, David A1 - Sarsakov, Vladimir A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - A polynomial translation of logic programs with nested expressions into disjunctive logic programs : preliminary report Y1 - 2002 ER - TY - JOUR A1 - Schaub, Torsten H. A1 - Woltran, Stefan T1 - Answer set programming unleashed! JF - Künstliche Intelligenz N2 - Answer Set Programming faces an increasing popularity for problem solving in various domains. While its modeling language allows us to express many complex problems in an easy way, its solving technology enables their effective resolution. In what follows, we detail some of the key factors of its success. Answer Set Programming [ASP; Brewka et al. Commun ACM 54(12):92–103, (2011)] is seeing a rapid proliferation in academia and industry due to its easy and flexible way to model and solve knowledge-intense combinatorial (optimization) problems. To this end, ASP offers a high-level modeling language paired with high-performance solving technology. As a result, ASP systems provide out-off-the-box, general-purpose search engines that allow for enumerating (optimal) solutions. They are represented as answer sets, each being a set of atoms representing a solution. The declarative approach of ASP allows a user to concentrate on a problem’s specification rather than the computational means to solve it. This makes ASP a prime candidate for rapid prototyping and an attractive tool for teaching key AI techniques since complex problems can be expressed in a succinct and elaboration tolerant way. This is eased by the tuning of ASP’s modeling language to knowledge representation and reasoning (KRR). The resulting impact is nicely reflected by a growing range of successful applications of ASP [Erdem et al. AI Mag 37(3):53–68, 2016; Falkner et al. Industrial applications of answer set programming. K++nstliche Intelligenz (2018)] Y1 - 2018 U6 - https://doi.org/10.1007/s13218-018-0550-z SN - 0933-1875 SN - 1610-1987 VL - 32 IS - 2-3 SP - 105 EP - 108 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Abseher, Michael A1 - Musliu, Nysret A1 - Woltran, Stefan A1 - Gebser, Martin A1 - Schaub, Torsten H. T1 - Shift Design with Answer Set Programming JF - Fundamenta informaticae N2 - Answer Set Programming (ASP) is a powerful declarative programming paradigm that has been successfully applied to many different domains. Recently, ASP has also proved successful for hard optimization problems like course timetabling and travel allotment. In this paper, we approach another important task, namely, the shift design problem, aiming at an alignment of a minimum number of shifts in order to meet required numbers of employees (which typically vary for different time periods) in such a way that over- and understaffing is minimized. We provide an ASP encoding of the shift design problem, which, to the best of our knowledge, has not been addressed by ASP yet. Our experimental results demonstrate that ASP is capable of improving the best known solutions to some benchmark problems. Other instances remain challenging and make the shift design problem an interesting benchmark for ASP-based optimization methods. Y1 - 2016 U6 - https://doi.org/10.3233/FI-2016-1396 SN - 0169-2968 SN - 1875-8681 VL - 147 SP - 1 EP - 25 PB - IOS Press CY - Amsterdam ER - TY - GEN A1 - Schaub, Torsten H. A1 - Woltran, Stefan T1 - Special issue on answer set programming T2 - Künstliche Intelligenz Y1 - 2018 U6 - https://doi.org/10.1007/s13218-018-0554-8 SN - 0933-1875 SN - 1610-1987 VL - 32 IS - 2-3 SP - 101 EP - 103 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Besnard, Philippe A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - Paraconsistent reasoning via quantified boolean formulas : Part II: Circumscribing inconsistent theories Y1 - 2003 SN - 3-540- 409494-5 ER - TY - JOUR A1 - Delgrande, James A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - A model-theoretic approach to belief change in answer set programming JF - ACM transactions on computational logic N2 - We address the problem of belief change in (nonmonotonic) logic programming under answer set semantics. Our formal techniques are analogous to those of distance-based belief revision in propositional logic. In particular, we build upon the model theory of logic programs furnished by SE interpretations, where an SE interpretation is a model of a logic program in the same way that a classical interpretation is a model of a propositional formula. Hence we extend techniques from the area of belief revision based on distance between models to belief change in logic programs. We first consider belief revision: for logic programs P and Q, the goal is to determine a program R that corresponds to the revision of P by Q, denoted P * Q. We investigate several operators, including (logic program) expansion and two revision operators based on the distance between the SE models of logic programs. It proves to be the case that expansion is an interesting operator in its own right, unlike in classical belief revision where it is relatively uninteresting. Expansion and revision are shown to satisfy a suite of interesting properties; in particular, our revision operators satisfy all or nearly all of the AGM postulates for revision. We next consider approaches for merging a set of logic programs, P-1,...,P-n. Again, our formal techniques are based on notions of relative distance between the SE models of the logic programs. Two approaches are examined. The first informally selects for each program P-i those models of P-i that vary the least from models of the other programs. The second approach informally selects those models of a program P-0 that are closest to the models of programs P-1,...,P-n. In this case, P-0 can be thought of as a set of database integrity constraints. We examine these operators with regards to how they satisfy relevant postulate sets. Last, we present encodings for computing the revision as well as the merging of logic programs within the same logic programming framework. This gives rise to a direct implementation of our approach in terms of off-the-shelf answer set solvers. These encodings also reflect the fact that our change operators do not increase the complexity of the base formalism. KW - Theory KW - Answer set programming KW - belief revision KW - belief merging KW - program encodings KW - strong equivalence Y1 - 2013 U6 - https://doi.org/10.1145/2480759.2480766 SN - 1529-3785 VL - 14 IS - 2 PB - Association for Computing Machinery CY - New York ER - TY - JOUR A1 - Brain, Martin A1 - Gebser, Martin A1 - Pührer, Jörg A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - Debugging ASP programs by means of ASP Y1 - 2007 SN - 978-3-540- 72199-4 ER - TY - JOUR A1 - Gebser, Martin A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Woltran, Stefan T1 - Alternative characterizations for program equivalence under aswer-set semantics : a preliminary report Y1 - 2007 ER - TY - GEN A1 - Schäpers, Björn A1 - Niemueller, Tim A1 - Lakemeyer, Gerhard A1 - Gebser, Martin A1 - Schaub, Torsten H. T1 - ASP-Based Time-Bounded Planning for Logistics Robots T2 - Twenty-Eighth International Conference on Automated Planning and Scheduling (ICAPS 2018) N2 - Manufacturing industries are undergoing a major paradigm shift towards more autonomy. Automated planning and scheduling then becomes a necessity. The Planning and Execution Competition for Logistics Robots in Simulation held at ICAPS is based on this scenario and provides an interesting testbed. However, the posed problem is challenging as also demonstrated by the somewhat weak results in 2017. The domain requires temporal reasoning and dealing with uncertainty. We propose a novel planning system based on Answer Set Programming and the Clingo solver to tackle these problems and incentivize robot cooperation. Our results show a significant performance improvement, both, in terms of lowering computational requirements and better game metrics. Y1 - 2018 SN - 2334-0835 SN - 2334-0843 SP - 509 EP - 517 PB - ASSOC Association for the Advancement of Artificial Intelligence CY - Palo Alto ER - TY - GEN A1 - Alviano, Mario A1 - Romero Davila, Javier A1 - Schaub, Torsten H. T1 - Preference Relations by Approximation T2 - Sixteenth International Conference on Principles of Knowledge Representation and Reasoning N2 - 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 Y1 - 2018 SP - 2 EP - 11 PB - AAAI Conference on Artificial Intelligence CY - Palo Alto ER - TY - GEN A1 - Neubauer, Kai A1 - Wanko, Philipp A1 - Schaub, Torsten H. A1 - Haubelt, Christian T1 - Enhancing symbolic system synthesis through ASPmT with partial assignment evaluation T2 - Proceedings of the Design, Automation & Test in Europe Conference & Exhibition (DATE), 2017 N2 - The design of embedded systems is becoming continuously more complex such that efficient system-level design methods are becoming crucial. Recently, combined Answer Set Programming (ASP) and Quantifier Free Integer Difference Logic (QF-IDL) solving has been shown to be a promising approach in system synthesis. However, this approach still has several restrictions limiting its applicability. In the paper at hand, we propose a novel ASP modulo Theories (ASPmT) system synthesis approach, which (i) supports more sophisticated system models, (ii) tightly integrates the QF-IDL solving into the ASP solving, and (iii) makes use of partial assignment checking. As a result, more realistic systems are considered and an early exclusion of infeasible solutions improves the entire system synthesis. Y1 - 2017 SN - 978-3-9815370-9-3 U6 - https://doi.org/10.23919/DATE.2017.7927005 SN - 1530-1591 SP - 306 EP - 309 PB - IEEE CY - New York ER - TY - JOUR A1 - Grell, Susanne A1 - Schaub, Torsten H. A1 - Selbig, Joachim T1 - Modelling biological networks by action languages via set programming Y1 - 2006 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/gebsch06c.pdf U6 - https://doi.org/10.1007/11799573 SN - 0302-9743 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - A Preference-Based Framework for Updating logic Programs : preliminary reports Y1 - 2006 UR - http://www.easychair.org/FLoC-06/PREFS-preproceedings.pdf ER - TY - JOUR A1 - Gressmann, Jean A1 - Janhunen, Tomi A1 - Mercer, Robert E. A1 - Schaub, Torsten H. A1 - Thiele, Sven A1 - Tichy, Richard T1 - On probing and multi-threading in platypus Y1 - 2006 UR - http://www2.in.tu-clausthal.de/~tmbehrens/NMR_Proc_TR4.pdf ER - TY - JOUR A1 - Anger, Christian A1 - Gebser, Martin A1 - Schaub, Torsten H. T1 - Approaching the core of unfounded sets Y1 - 2006 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/angesc06a.pdf ER - TY - JOUR A1 - Gerbser, Martin A1 - Schaub, Torsten H. T1 - Tableau calculi for answer set programming Y1 - 2006 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/gebsch06c.pdf U6 - https://doi.org/10.1007/11799573 SN - 0302-9743 ER - TY - JOUR A1 - Anger, Christian A1 - Gebser, Martin A1 - Janhunen, Tomi A1 - Schaub, Torsten H. T1 - What's a head without a body? Y1 - 2006 ER - TY - JOUR A1 - Gerbser, Martin A1 - Schaub, Torsten H. T1 - Characterizing (ASP) inferences by unit propagation Y1 - 2006 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - A preference-based framework for updating logic programs Y1 - 2007 SN - 978-3-540- 72199-4 ER - TY - JOUR A1 - Mileo, Alessandra A1 - Schaub, Torsten H. T1 - Qualitative constraint enforcement in advanced policy specification Y1 - 2007 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Lang, Jérôme A1 - Schaub, Torsten H. T1 - Belief change based on global minimisation Y1 - 2007 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Graphs and colorings for answer set programming N2 - We investigate the usage of rule dependency graphs and their colorings for characterizing and computing answer sets of logic programs. This approach provides us with insights into the interplay between rules when inducing answer sets. We start with different characterizations of answer sets in terms of totally colored dependency graphs that differ ill graph-theoretical aspects. We then develop a series of operational characterizations of answer sets in terms of operators on partial colorings. In analogy to the notion of a derivation in proof theory, our operational characterizations are expressed as (non-deterministically formed) sequences of colorings, turning an uncolored graph into a totally colored one. In this way, we obtain an operational framework in which different combinations of operators result in different formal properties. Among others, we identify the basic strategy employed by the noMoRe system and justify its algorithmic approach. Furthermore, we distinguish operations corresponding to Fitting's operator as well as to well-founded semantics Y1 - 2006 UR - http://www.cs.kuleuven.ac.be/~dtai/projects/ALP//TPLP/ U6 - https://doi.org/10.1017/S1471068405002528 SN - 1471-0684 ER - TY - JOUR A1 - Gebser, Martin A1 - Schaub, Torsten H. A1 - Thiele, Sven T1 - GrinGo : a new grounder for answer set programming Y1 - 2007 SN - 978-3-540- 72199-4 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Graphs and cologings for answer set programming : adridged report Y1 - 2004 SN - 3-540- 20721-x ER - TY - JOUR A1 - Boesel, Andreas A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Profiling answer set programming : the visualization component of the noMoRe System Y1 - 2004 SN - 3-540-23242-7 ER - TY - JOUR A1 - Gressmann, Jean A1 - Janhunen, Tomi A1 - Mercer, Robert E. A1 - Schaub, Torsten H. A1 - Thiele, Sven A1 - Tichy, Richard T1 - On probing and multi-threading in platypus Y1 - 2006 ER - TY - JOUR A1 - Mileo, Alessandra A1 - Schaub, Torsten H. T1 - Extending ordered disjunctions for policy enforcement : preliminary report Y1 - 2006 UR - http://www.easychair.org/FLoC-06/PREFS-preproceedings.pdf ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Liu, Daphne H. A1 - Schaub, Torsten H. A1 - Thiele, Sven T1 - COBA 2.0 : a consistency-based belief change system Y1 - 2006 UR - http://www2.in.tu-clausthal.de/~tmbehrens/NMR_Proc_TR4.pdf ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - An Extended Query language for action languages (and its application to aggregates and preferences) Y1 - 2006 UR - http://www2.in.tu-clausthal.de/~tmbehrens/NMR_Proc_TR4.pdf ER - TY - JOUR A1 - Anger, Christian A1 - Gebser, Martin A1 - Linke, Thomas A1 - Neumann, Andre A1 - Schaub, Torsten H. T1 - The nomore++ approach to answer set solving Y1 - 2005 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/angelinesc05c.pdf ER - TY - JOUR A1 - Gressmann, Jean A1 - Janhunen, Tomi A1 - Mercer, Robert E. A1 - Schaub, Torsten H. A1 - Thiele, Sven A1 - Tichy, Richard T1 - Platypus : a platform for distributed answer set solving Y1 - 2005 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/grjamescthti05a.pdf ER - TY - JOUR A1 - Anger, Christian A1 - Gebser, Martin A1 - Linke, Thomas A1 - Neumann, Andre A1 - Schaub, Torsten H. T1 - The nomore++ approach to answer set solving Y1 - 2005 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/angelinesc05c.pdf ER - TY - JOUR A1 - Grell, Susanne A1 - Konczak, Kathrin A1 - Schaub, Torsten H. T1 - nomore) : a system for computing preferred Answer Sets Y1 - 2005 SN - 0302-9743 ER - TY - JOUR A1 - Anger, Christian A1 - Konczak, Kathrin A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - A Glimpse of Answer Set Programming Y1 - 2005 UR - http://www.cs.uni-potsdam.de/~konczak/Papers/ankolisc05.pdf SN - 0170-4516 ER - TY - JOUR A1 - Gebser, Martin A1 - Schaub, Torsten H. T1 - Loops: Relevant or Redundant? Y1 - 2005 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/gebsch05a.pdf ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Expressing default logic variants in default logic N2 - Reiter's default logic is one of the best known and most studied of the approaches to nonmonotonic reasoning. Several variants of default logic have subsequently been proposed to give systems with properties differing from the original. In this paper, we examine the relationship between default logic and its major variants. We accomplish this by translating a default theory under a variant interpretation into a second default theory, under the original Reiter semantics, wherein the variant interpretation is respected. That is, in each case we show that, given an extension of a translated theory, one may extract an extension of the original variant default logic theory. We show how constrained, rational, justified, and cumulative default logic can be expressed in Reiter's default logic. As well, we show how Reiter's default logic can be expressed in rational default logic. From this, we suggest that any such variant can be similarly treated. Consequently, we provide a unification of default logics, showing how the original formulation of default logic may express its variants. Moreover, the translations clearly express the relationships between alternative approaches to default logic. The translations themselves are shown to generally have good properties. Thus, in at least a theoretical sense, we show that these variants are in a sense superfluous, in that for any of these variants of default logic, we can exactly mimic the behaviour of a variant in standard default logic. As well, the translations lend insight into means of classifying the expressive power of default logic variants; specifically we suggest that the property of semi-monotonicity represents a division with respect to expressibility, whereas regularity and cumulativity do not Y1 - 2005 SN - 0955-792X ER - TY - JOUR A1 - Gebser, Martin A1 - Liu, Lengning A1 - Namasivayam, Gayathri A1 - Neumann, André A1 - Schaub, Torsten H. A1 - Truszczynski, Miroslaw T1 - The first answer set programming system competition Y1 - 2007 SN - 978-3-540- 72199-4 ER - TY - JOUR A1 - Borchert, P. A1 - Anger, Christian A1 - Schaub, Torsten H. A1 - Truszczynski, M. T1 - Towards systematic benchmarking in answer set programming : the dagstuhl initiative Y1 - 2004 SN - 3-540- 20721-x ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Two approaches to merging knowledge bases Y1 - 2004 SN - 3-540-23242-7 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - Domain-specific preference for causal reasoning and planning Y1 - 2004 SN - 1-577-35201-7 ER - TY - JOUR A1 - Flöter, André A1 - Selbig, Joachim A1 - Schaub, Torsten H. T1 - Finding metabolic pathways in decision forests Y1 - 2004 SN - 3-540-23221-4 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Consistency-based approaches to merging knowledge based : preliminary report Y1 - 2004 UR - http://www.pims.math.ca/science/2004/NMR/papers/paper17.pdf SN - 92-990021-0-X ER - TY - JOUR A1 - Flöter, André A1 - Nicolas, Jacques A1 - Schaub, Torsten H. A1 - Selbig, Joachim T1 - Threshold extraction in metabolite concentration data N2 - Motivation: Continued development of analytical techniques based on gas chromatography and mass spectrometry now facilitates the generation of larger sets of metabolite concentration data. An important step towards the understanding of metabolite dynamics is the recognition of stable states where metabolite concentrations exhibit a simple behaviour. Such states can be characterized through the identification of significant thresholds in the concentrations. But general techniques for finding discretization thresholds in continuous data prove to be practically insufficient for detecting states due to the weak conditional dependences in concentration data. Results: We introduce a method of recognizing states in the framework of decision tree induction. It is based upon a global analysis of decision forests where stability and quality are evaluated. It leads to the detection of thresholds that are both comprehensible and robust. Applied to metabolite concentration data, this method has led to the discovery of hidden states in the corresponding variables. Some of these reflect known properties of the biological experiments, and others point to putative new states Y1 - 2004 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Wang, Kewen T1 - A classification and survey of preference handling approchaches in nonmonotonic reasoning N2 - In recent years, there has been a large amount of disparate work concerning the representation and reasoning with qualitative preferential information by means of approaches to nonmonotonic reasoning. Given the variety of underlying systems, assumptions, motivations, and intuitions, it is difficult to compare or relate one approach with another. Here, we present an overview and classification for approaches to dealing with preference. A set of criteria for classifying approaches is given, followed by a set of desiderata that an approach might be expected to satisfy. A comprehensive set of approaches is subsequently given and classified with respect to these sets of underlying principles Y1 - 2004 SN - 0824-7935 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Reasoning with sets of preferences in default logic N2 - We present a general approach for representing and reasoning with sets of defaults in default logic, focusing on reasoning about preferences among sets of defaults. First, we consider how to control the application of a set of defaults so that either all apply (if possible) or none do (if not). From this, an approach to dealing with preferences among sets of default rules is developed. We begin with an ordered default theory, consisting of a standard default theory, but with possible preferences on sets of rules. This theory is transformed into a second, standard default theory wherein the preferences are respected. The approach differs from other work, in that we obtain standard default theories and do not rely on prioritized versions of default logic. In practical terms this means we can immediately use existing default logic theorem provers for an implementation. Also, we directly generate just those extensions containing the most preferred applied rules; in contrast, most previous approaches generate all extensions, then select the most preferred. In a major application of the approach, we show how semimonotonic default theories can be encoded so that reasoning can be carried out at the object level. With this, we can reason about default extensions from within the framework of a standard default logic. Hence one can encode notions such as skeptical and credulous conclusions, and can reason about such conclusions within a single extension Y1 - 2004 SN - 0824-7935 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - A framework for compiling preferences in logic programs Y1 - 2003 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Reasoning credulously and skeptically within a single extension Y1 - 2003 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Graphs and colorings for answer set programming : abridged report Y1 - 2003 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/kolisch03a.pdf SN - 1613-0073 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - On the relation between Reiterïs default logic and its (major) variants Y1 - 2003 SN - 3-540- 409494-5 ER - TY - JOUR A1 - Besnard, Philippe A1 - Mercer, Robert E. A1 - Schaub, Torsten H. T1 - Optimality theory throught default logic Y1 - 2003 SN - 3-540-20059-2 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Schaub, Torsten H. A1 - Linke, Thomas T1 - Graphs and colorings for answer set programming with prefernces : preliminary report Y1 - 2003 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/koschli03a.pdf SN - 1613-0073 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Gharib, Mona A1 - Mercer, Robert E. A1 - Risch, V. A1 - Schaub, Torsten H. T1 - Lukaszewicz-style answer set programming : a preliminary report Y1 - 2003 UR - http://sunsite.informatik.rwth-aachen.de/Publications/CEUR-WS/Vol-78/ SN - 1613-0073 ER - TY - JOUR A1 - Schaub, Torsten H. A1 - Wang, Kewen T1 - A semantic framework for prefernce handling in answer set programming Y1 - 2003 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - A concictency-based paradigm for belief change Y1 - 2003 SN - 0004-3702 ER - TY - JOUR A1 - Schaub, Torsten H. T1 - Antwortmengenprogrammierung Y1 - 2003 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Schaub, Torsten H. A1 - Linke, Thomas T1 - Graphs and colorings for answer set programming with preferences N2 - The integration of preferences into answer set programming constitutes an important practical device for distinguishing certain preferred answer sets from non-preferred ones. To this end, we elaborate upon rule dependency graphs and their colorings for characterizing different preference handling strategies found in the literature. We start from a characterization of (three types of) preferred answer sets in terms of totally colored dependency graphs. In particular, we demonstrate that this approach allows us to capture all three approaches to preferences in a uniform setting by means of the concept of a height function. In turn, we exemplarily develop an operational characterization of preferred answer sets in terms of operators on partial colorings for one particular strategy. In analogy to the notion of a derivation in proof theory, our operational characterization is expressed as a (non-deterministically formed) sequence of colorings, gradually turning an uncolored graph into a totally colored one Y1 - 2003 SN - 0169-2968 ER - TY - JOUR A1 - Flöter, André A1 - Nicolas, Jacques A1 - Schaub, Torsten H. A1 - Selbig, Joachim T1 - Threshold extraction in metabolite concentration data Y1 - 2003 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/floeterGCB2003.pdf ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Wang, Kewen T1 - Towards a classification of preference handling approaches in nonmonotonic reasoning Y1 - 2002 SN - 1-577-35166-5 ER - TY - JOUR A1 - Besnard, Philippe A1 - Mercer, Robert E. A1 - Schaub, Torsten H. T1 - Optimality Theory via Default Logic Y1 - 2002 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Reasoning credulously and skeptically within a single extension Y1 - 2002 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Hunter, Anthony A1 - Schaub, Torsten H. T1 - COBA: a consistency-based belief revision system Y1 - 2002 SN - 3-540-44190-5 ER - TY - JOUR A1 - Schaub, Torsten H. A1 - Wang, T. T1 - Preferred well-founded semantics for logic programming by alternating fixpoints : preliminary report Y1 - 2002 ER - TY - JOUR A1 - Bobda, Christophe A1 - Yonga, Franck A1 - Gebser, Martin A1 - Ishebabi, Harold A1 - Schaub, Torsten H. T1 - High-level synthesis of on-chip multiprocessor architectures based on answer set programming JF - Journal of Parallel and Distributed Computing N2 - We present a system-level synthesis approach for heterogeneous multi-processor on chip, based on Answer Set Programming(ASP). Starting with a high-level description of an application, its timing constraints and the physical constraints of the target device, our goal is to produce the optimal computing infrastructure made of heterogeneous processors, peripherals, memories and communication components. Optimization aims at maximizing speed, while minimizing chip area. Also, a scheduler must be produced that fulfills the real-time requirements of the application. Even though our approach will work for application specific integrated circuits, we have chosen FPGA as target device in this work because of their reconfiguration capabilities which makes it possible to explore several design alternatives. This paper addresses the bottleneck of problem representation size by providing a direct and compact ASP encoding for automatic synthesis that is semantically equivalent to previously established ILP and ASP models. We describe a use-case in which designers specify their applications in C/C++ from which optimum systems can be derived. We demonstrate the superiority of our approach toward existing heuristics and exact methods with synthesis results on a set of realistic case studies. (C) 2018 Elsevier Inc. All rights reserved. KW - System design KW - Architecture synthesis KW - Answer set programming KW - Multi-objective optimization KW - Technology mapping KW - Reconfigurable architecture Y1 - 2018 U6 - https://doi.org/10.1016/j.jpdc.2018.02.010 SN - 0743-7315 SN - 1096-0848 VL - 117 SP - 161 EP - 179 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Cabalar, Pedro A1 - Kaminski, Roland A1 - Schaub, Torsten H. A1 - Schuhmann, Anna T1 - Temporal answer set programming on finite traces JF - Theory and practice of logic programming N2 - In this paper, we introduce an alternative approach to Temporal Answer Set Programming that relies on a variation of Temporal Equilibrium Logic (TEL) for finite traces. This approach allows us to even out the expressiveness of TEL over infinite traces with the computational capacity of (incremental) Answer Set Programming (ASP). Also, we argue that finite traces are more natural when reasoning about action and change. As a result, our approach is readily implementable via multi-shot ASP systems and benefits from an extension of ASP's full-fledged input language with temporal operators. This includes future as well as past operators whose combination offers a rich temporal modeling language. For computation, we identify the class of temporal logic programs and prove that it constitutes a normal form for our approach. Finally, we outline two implementations, a generic one and an extension of the ASP system clingo. Under consideration for publication in Theory and Practice of Logic Programming (TPLP) Y1 - 2018 U6 - https://doi.org/10.1017/S1471068418000297 SN - 1471-0684 SN - 1475-3081 VL - 18 IS - 3-4 SP - 406 EP - 420 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Gebser, Martin A1 - Obermeier, Philipp A1 - Otto, Thomas A1 - Schaub, Torsten H. A1 - Sabuncu, Orkunt A1 - Van Nguyen, A1 - Tran Cao Son, T1 - Experimenting with robotic intra-logistics domains JF - Theory and practice of logic programming N2 - We introduce the asprilo1 framework to facilitate experimental studies of approaches addressing complex dynamic applications. For this purpose, we have chosen the domain of robotic intra-logistics. This domain is not only highly relevant in the context of today's fourth industrial revolution but it moreover combines a multitude of challenging issues within a single uniform framework. This includes multi-agent planning, reasoning about action, change, resources, strategies, etc. In return, asprilo allows users to study alternative solutions as regards effectiveness and scalability. Although asprilo relies on Answer Set Programming and Python, it is readily usable by any system complying with its fact-oriented interface format. This makes it attractive for benchmarking and teaching well beyond logic programming. More precisely, asprilo consists of a versatile benchmark generator, solution checker and visualizer as well as a bunch of reference encodings featuring various ASP techniques. Importantly, the visualizer's animation capabilities are indispensable for complex scenarios like intra-logistics in order to inspect valid as well as invalid solution candidates. Also, it allows for graphically editing benchmark layouts that can be used as a basis for generating benchmark suites. Y1 - 2018 U6 - https://doi.org/10.1017/S1471068418000200 SN - 1471-0684 SN - 1475-3081 VL - 18 IS - 3-4 SP - 502 EP - 519 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Gebser, Martin A1 - Obermeier, Philipp A1 - Schaub, Torsten H. A1 - Ratsch-Heitmann, Michel A1 - Runge, Mario T1 - Routing driverless transport vehicles in car assembly with answer set programming JF - Theory and practice of logic programming N2 - Automated storage and retrieval systems are principal components of modern production and warehouse facilities. In particular, automated guided vehicles nowadays substitute human-operated pallet trucks in transporting production materials between storage locations and assembly stations. While low-level control systems take care of navigating such driverless vehicles along programmed routes and avoid collisions even under unforeseen circumstances, in the common case of multiple vehicles sharing the same operation area, the problem remains how to set up routes such that a collection of transport tasks is accomplished most effectively. We address this prevalent problem in the context of car assembly at Mercedes-Benz Ludwigsfelde GmbH, a large-scale producer of commercial vehicles, where routes for automated guided vehicles used in the production process have traditionally been hand-coded by human engineers. Such adhoc methods may suffice as long as a running production process remains in place, while any change in the factory layout or production targets necessitates tedious manual reconfiguration, not to mention the missing portability between different production plants. Unlike this, we propose a declarative approach based on Answer Set Programming to optimize the routes taken by automated guided vehicles for accomplishing transport tasks. The advantages include a transparent and executable problem formalization, provable optimality of routes relative to objective criteria, as well as elaboration tolerance towards particular factory layouts and production targets. Moreover, we demonstrate that our approach is efficient enough to deal with the transport tasks evolving in realistic production processes at the car factory of Mercedes-Benz Ludwigsfelde GmbH. KW - automated guided vehicle routing KW - car assembly operations KW - answer set programming Y1 - 2018 U6 - https://doi.org/10.1017/S1471068418000182 SN - 1471-0684 SN - 1475-3081 VL - 18 IS - 3-4 SP - 520 EP - 534 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Gebser, Martin A1 - Kaminski, Roland A1 - Kaufmann, Benjamin A1 - Lühne, Patrick A1 - Obermeier, Philipp A1 - Ostrowski, Max A1 - Romero Davila, Javier A1 - Schaub, Torsten H. A1 - Schellhorn, Sebastian A1 - Wanko, Philipp T1 - The Potsdam Answer Set Solving Collection 5.0 JF - Künstliche Intelligenz N2 - The Potsdam answer set solving collection, or Potassco for short, bundles various tools implementing and/or applying answer set programming. The article at hand succeeds an earlier description of the Potassco project published in Gebser et al. (AI Commun 24(2):107-124, 2011). Hence, we concentrate in what follows on the major features of the most recent, fifth generation of the ASP system clingo and highlight some recent resulting application systems. Y1 - 2018 U6 - https://doi.org/10.1007/s13218-018-0528-x SN - 0933-1875 SN - 1610-1987 VL - 32 IS - 2-3 SP - 181 EP - 182 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Haubelt, Christian A1 - Neubauer, Kai A1 - Schaub, Torsten H. A1 - Wanko, Philipp T1 - Design space exploration with answer set programming JF - Künstliche Intelligenz N2 - The aim of our project design space exploration with answer set programming is to develop a general framework based on Answer Set Programming (ASP) that finds valid solutions to the system design problem and simultaneously performs Design Space Exploration (DSE) to find the most favorable alternatives. We leverage recent developments in ASP solving that allow for tight integration of background theories to create a holistic framework for effective DSE. Y1 - 2018 U6 - https://doi.org/10.1007/s13218-018-0530-3 SN - 0933-1875 SN - 1610-1987 VL - 32 IS - 2-3 SP - 205 EP - 206 PB - Springer CY - Heidelberg ER - TY - GEN A1 - Lifschitz, Vladimir A1 - Schaub, Torsten H. A1 - Woltran, Stefan T1 - Interview with Vladimir Lifschitz T2 - Künstliche Intelligenz N2 - This interview with Vladimir Lifschitz was conducted by Torsten Schaub at the University of Texas at Austin in August 2017. The question set was compiled by Torsten Schaub and Stefan Woltran. Y1 - 2018 U6 - https://doi.org/10.1007/s13218-018-0552-x SN - 0933-1875 SN - 1610-1987 VL - 32 IS - 2-3 SP - 213 EP - 218 PB - Springer CY - Heidelberg ER - TY - GEN A1 - Brewka, Gerhard A1 - Schaub, Torsten H. A1 - Woltran, Stefan T1 - Interview with Gerhard Brewka T2 - Künstliche Intelligenz N2 - This interview with Gerhard Brewka was conducted by correspondance in May 2018. The question set was compiled by Torsten Schaub and Stefan Woltran. Y1 - 2018 U6 - https://doi.org/10.1007/s13218-018-0549-5 SN - 0933-1875 SN - 1610-1987 VL - 32 IS - 2-3 SP - 219 EP - 221 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Dimopoulos, Yannis A1 - Gebser, Martin A1 - Lühne, Patrick A1 - Romero Davila, Javier A1 - Schaub, Torsten H. T1 - plasp 3 BT - Towards Effective ASP Planning JF - Theory and practice of logic programming N2 - We describe the new version of the Planning Domain Definition Language (PDDL)-to-Answer Set Programming (ASP) translator plasp. First, it widens the range of accepted PDDL features. Second, it contains novel planning encodings, some inspired by Satisfiability Testing (SAT) planning and others exploiting ASP features such as well-foundedness. All of them are designed for handling multivalued fluents in order to capture both PDDL as well as SAS planning formats. Third, enabled by multishot ASP solving, it offers advanced planning algorithms also borrowed from SAT planning. As a result, plasp provides us with an ASP-based framework for studying a variety of planning techniques in a uniform setting. Finally, we demonstrate in an empirical analysis that these techniques have a significant impact on the performance of ASP planning. KW - knowledge representation and nonmonotonic reasoning KW - technical notes and rapid communications KW - answer set programming KW - automated planning KW - action and change Y1 - 2019 U6 - https://doi.org/10.1017/S1471068418000583 SN - 1471-0684 SN - 1475-3081 VL - 19 IS - 3 SP - 477 EP - 504 PB - Cambridge Univ. Press CY - New York ER - TY - GEN A1 - Neubauer, Kai A1 - Haubelt, Christian A1 - Wanko, Philipp A1 - Schaub, Torsten H. T1 - Utilizing quad-trees for efficient design space exploration with partial assignment evaluation T2 - 2018 23rd Asia and South Pacific Design Automation Conference (ASP-DAC) N2 - Recently, it has been shown that constraint-based symbolic solving techniques offer an efficient way for deciding binding and routing options in order to obtain a feasible system level implementation. In combination with various background theories, a feasibility analysis of the resulting system may already be performed on partial solutions. That is, infeasible subsets of mapping and routing options can be pruned early in the decision process, which fastens the solving accordingly. However, allowing a proper design space exploration including multi-objective optimization also requires an efficient structure for storing and managing non-dominated solutions. In this work, we propose and study the usage of the Quad-Tree data structure in the context of partial assignment evaluation during system synthesis. Out experiments show that unnecessary dominance checks can be avoided, which indicates a preference of Quad-Trees over a commonly used list-based implementation for large combinatorial optimization problems. Y1 - 2018 SN - 978-1-5090-0602-1 U6 - https://doi.org/10.1109/ASPDAC.2018.8297362 SN - 2153-6961 SP - 434 EP - 439 PB - IEEE CY - New York ER - TY - GEN A1 - Bosser, Anne-Gwenn A1 - Cabalar, Pedro A1 - Dieguez, Martin A1 - Schaub, Torsten H. T1 - Introducing temporal stable models for linear dynamic logic T2 - 16th International Conference on Principles of Knowledge Representation and Reasoning N2 - We propose a new temporal extension of the logic of Here-and-There (HT) and its equilibria obtained by combining it with dynamic logic over (linear) traces. Unlike previous temporal extensions of HT based on linear temporal logic, the dynamic logic features allow us to reason about the composition of actions. For instance, this can be used to exercise fine grained control when planning in robotics, as exemplified by GOLOG. In this paper, we lay the foundations of our approach, and refer to it as Linear Dynamic Equilibrium Logic, or simply DEL. We start by developing the formal framework of DEL and provide relevant characteristic results. Among them, we elaborate upon the relationships to traditional linear dynamic logic and previous temporal extensions of HT. Y1 - 2018 UR - https://www.dc.fi.udc.es/~cabalar/del.pdf SP - 12 EP - 21 PB - ASSOC Association for the Advancement of Artificial Intelligence CY - Palo Alto ER - TY - GEN A1 - Neubauer, Kai A1 - Wanko, Philipp A1 - Schaub, Torsten H. A1 - Haubelt, Christian T1 - Exact multi-objective design space exploration using ASPmT T2 - Proceedings of the 2018 Design, Automation & Test in Europe Conference & Exhibition (DATE) N2 - An efficient Design Space Exploration (DSE) is imperative for the design of modern, highly complex embedded systems in order to steer the development towards optimal design points. The early evaluation of design decisions at system-level abstraction layer helps to find promising regions for subsequent development steps in lower abstraction levels by diminishing the complexity of the search problem. In recent works, symbolic techniques, especially Answer Set Programming (ASP) modulo Theories (ASPmT), have been shown to find feasible solutions of highly complex system-level synthesis problems with non-linear constraints very efficiently. In this paper, we present a novel approach to a holistic system-level DSE based on ASPmT. To this end, we include additional background theories that concurrently guarantee compliance with hard constraints and perform the simultaneous optimization of several design objectives. We implement and compare our approach with a state-of-the-art preference handling framework for ASP. Experimental results indicate that our proposed method produces better solutions with respect to both diversity and convergence to the true Pareto front. Y1 - 2018 SN - 978-3-9819-2630-9 U6 - https://doi.org/10.23919/DATE.2018.8342014 SN - 1530-1591 SN - 1558-1101 SP - 257 EP - 260 PB - IEEE CY - New York ER - TY - GEN A1 - Cabalar, Pedro A1 - Fandinno, Jorge A1 - Schaub, Torsten H. A1 - Schellhorn, Sebastian T1 - Lower Bound Founded Logic of Here-and-There T2 - Logics in Artificial Intelligence N2 - A distinguishing feature of Answer Set Programming is that all atoms belonging to a stable model must be founded. That is, an atom must not only be true but provably true. This can be made precise by means of the constructive logic of Here-and-There, whose equilibrium models correspond to stable models. One way of looking at foundedness is to regard Boolean truth values as ordered by letting true be greater than false. Then, each Boolean variable takes the smallest truth value that can be proven for it. This idea was generalized by Aziz to ordered domains and applied to constraint satisfaction problems. As before, the idea is that a, say integer, variable gets only assigned to the smallest integer that can be justified. In this paper, we present a logical reconstruction of Aziz’ idea in the setting of the logic of Here-and-There. More precisely, we start by defining the logic of Here-and-There with lower bound founded variables along with its equilibrium models and elaborate upon its formal properties. Finally, we compare our approach with related ones and sketch future work. Y1 - 2019 SN - 978-3-030-19570-0 SN - 978-3-030-19569-4 U6 - https://doi.org/10.1007/978-3-030-19570-0_34 SN - 0302-9743 SN - 1611-3349 VL - 11468 SP - 509 EP - 525 PB - Springer CY - Cham ER - TY - JOUR A1 - Gebser, Martin A1 - Kaminski, Roland A1 - Kaufmann, Benjamin A1 - Schaub, Torsten H. T1 - Multi-shot ASP solving with clingo JF - Theory and practice of logic programming N2 - We introduce a new flexible paradigm of grounding and solving in Answer Set Programming (ASP), which we refer to as multi-shot ASP solving, and present its implementation in the ASP system clingo. Multi-shot ASP solving features grounding and solving processes that deal with continuously changing logic programs. In doing so, they remain operative and accommodate changes in a seamless way. For instance, such processes allow for advanced forms of search, as in optimization or theory solving, or interaction with an environment, as in robotics or query answering. Common to them is that the problem specification evolves during the reasoning process, either because data or constraints are added, deleted, or replaced. This evolutionary aspect adds another dimension to ASP since it brings about state changing operations. We address this issue by providing an operational semantics that characterizes grounding and solving processes in multi-shot ASP solving. This characterization provides a semantic account of grounder and solver states along with the operations manipulating them. The operative nature of multi-shot solving avoids redundancies in relaunching grounder and solver programs and benefits from the solver's learning capacities. clingo accomplishes this by complementing ASP's declarative input language with control capacities. On the declarative side, a new directive allows for structuring logic programs into named and parameterizable subprograms. The grounding and integration of these subprograms into the solving process is completely modular and fully controllable from the procedural side. To this end, clingo offers a new application programming interface that is conveniently accessible via scripting languages. By strictly separating logic and control, clingo also abolishes the need for dedicated systems for incremental and reactive reasoning, like iclingo and oclingo, respectively, and its flexibility goes well beyond the advanced yet still rigid solving processes of the latter. Y1 - 2018 U6 - https://doi.org/10.1017/S1471068418000054 SN - 1471-0684 SN - 1475-3081 VL - 19 IS - 1 SP - 27 EP - 82 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Frioux, Clémence A1 - Schaub, Torsten H. A1 - Schellhorn, Sebastian A1 - Siegel, Anne A1 - Wanko, Philipp T1 - Hybrid metabolic network completion JF - Theory and practice of logic programming N2 - Metabolic networks play a crucial role in biology since they capture all chemical reactions in an organism. While there are networks of high quality for many model organisms, networks for less studied organisms are often of poor quality and suffer from incompleteness. To this end, we introduced in previous work an answer set programming (ASP)-based approach to metabolic network completion. Although this qualitative approach allows for restoring moderately degraded networks, it fails to restore highly degraded ones. This is because it ignores quantitative constraints capturing reaction rates. To address this problem, we propose a hybrid approach to metabolic network completion that integrates our qualitative ASP approach with quantitative means for capturing reaction rates. We begin by formally reconciling existing stoichiometric and topological approaches to network completion in a unified formalism. With it, we develop a hybrid ASP encoding and rely upon the theory reasoning capacities of the ASP system dingo for solving the resulting logic program with linear constraints over reals. We empirically evaluate our approach by means of the metabolic network of Escherichia coli. Our analysis shows that our novel approach yields greatly superior results than obtainable from purely qualitative or quantitative approaches. KW - answer set programming KW - metabolic network KW - gap-filling KW - linear programming KW - hybrid solving KW - bioinformatics Y1 - 2018 U6 - https://doi.org/10.1017/S1471068418000455 SN - 1471-0684 SN - 1475-3081 VL - 19 IS - 1 SP - 83 EP - 108 PB - Cambridge University Press CY - New York ER - TY - JOUR A1 - Banbara, Mutsunori A1 - Inoue, Katsumi A1 - Kaufmann, Benjamin A1 - Okimoto, Tenda A1 - Schaub, Torsten H. A1 - Soh, Takehide A1 - Tamura, Naoyuki A1 - Wanko, Philipp T1 - teaspoon BT - solving the curriculum-based course timetabling problems with answer set programming JF - Annals of operation research N2 - Answer Set Programming (ASP) is an approach to declarative problem solving, combining a rich yet simple modeling language with high performance solving capacities. We here develop an ASP-based approach to curriculum-based course timetabling (CB-CTT), one of the most widely studied course timetabling problems. The resulting teaspoon system reads a CB-CTT instance of a standard input format and converts it into a set of ASP facts. In turn, these facts are combined with a first-order encoding for CB-CTT solving, which can subsequently be solved by any off-the-shelf ASP systems. We establish the competitiveness of our approach by empirically contrasting it to the best known bounds obtained so far via dedicated implementations. Furthermore, we extend the teaspoon system to multi-objective course timetabling and consider minimal perturbation problems. KW - Educational timetabling KW - Course timetabling KW - Answer set programming KW - Multi-objective optimization KW - Minimal perturbation problems Y1 - 2018 U6 - https://doi.org/10.1007/s10479-018-2757-7 SN - 0254-5330 SN - 1572-9338 VL - 275 IS - 1 SP - 3 EP - 37 PB - Springer CY - Dordrecht ER - TY - GEN A1 - Dworschak, Steve A1 - Grell, Susanne A1 - Nikiforova, Victoria J. A1 - Schaub, Torsten H. A1 - Selbig, Joachim T1 - Modeling biological networks by action languages via answer set programming T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - We describe an approach to modeling biological networks by action languages via answer set programming. To this end, we propose an action language for modeling biological networks, building on previous work by Baral et al. We introduce its syntax and semantics along with a translation into answer set programming, an efficient Boolean Constraint Programming Paradigm. Finally, we describe one of its applications, namely, the sulfur starvation response-pathway of the model plant Arabidopsis thaliana and sketch the functionality of our system and its usage. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 843 KW - biological network model KW - action language KW - answer set programming Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-429846 SN - 1866-8372 IS - 843 ER - TY - JOUR A1 - Bibel, Wolfgang A1 - Brüning, Stefan A1 - Otten, Jens A1 - Rath, Thomas A1 - Schaub, Torsten H. T1 - Compressions and extensions Y1 - 1998 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Compiling specificity into approaches to nonmonotonic reasoning Y1 - 1997 SN - 0004-3702 ER - TY - JOUR A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Towards a classification of default logic Y1 - 1997 ER - TY - JOUR A1 - Schaub, Torsten H. A1 - Brüning, Stefan T1 - Prolog technology for default reasoning Y1 - 1996 SN - 0-471-96809-9 ER - TY - JOUR A1 - Besnard, Philippe A1 - Schaub, Torsten H. T1 - A simple signed system for paraconsistent reasoning Y1 - 1996 SN - 3-540-61630-6 ER - TY - JOUR A1 - Schaub, Torsten H. A1 - Thielscher, Michael T1 - Skeptical query-answering in constrained default logic Y1 - 1996 SN - 3-540-61313-7 ER - TY - JOUR A1 - Schaub, Torsten H. A1 - Brüning, Stefan A1 - Nicolas, Pascal T1 - XRay : a prolog technology theorem prover for default reasoning: a system description Y1 - 1996 SN - 3-540-61511-3 ER - TY - JOUR A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Putting default logics in perspective Y1 - 1996 SN - 3-540-61708-6 ER - TY - JOUR A1 - Brüning, Stefan A1 - Schaub, Torsten H. T1 - A model-based approach to consistency-checking Y1 - 1996 SN - 3-540-61286-6 ER - TY - JOUR A1 - Gebser, Martin A1 - Kaufmann, Benjamin A1 - Neumann, André A1 - Schaub, Torsten H. T1 - Conflict-driven answer set enumeration Y1 - 2007 SN - 978-3-540- 72199-4 ER - TY - JOUR A1 - Gebser, Martin A1 - Kaufmann, Benjamin A1 - Neumann, André A1 - Schaub, Torsten H. T1 - Conflict-driven answer set solving Y1 - 2007 SN - 978-1-57735-323-2 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Liu, Daphne H. A1 - Schaub, Torsten H. A1 - Thiele, Sven T1 - COBA 2.0 : a consistency-based belief change system Y1 - 2007 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - A consistency-based framework for merging knowledge bases Y1 - 2007 SN - 1570-8683 ER -