TY  - JOUR
A1  - Hoos, Holger
A1  - Kaminski, Roland
A1  - Lindauer, Marius
A1  - Schaub, Torsten H.
T1  - aspeed: Solver scheduling via answer set programming
JF  - Theory and practice of logic programming
N2  - Although Boolean Constraint Technology has made tremendous progress over the last decade, the efficacy of state-of-the-art solvers is known to vary considerably across different types of problem instances, and is known to depend strongly on algorithm parameters. This problem was addressed by means of a simple, yet effective approach using handmade, uniform, and unordered schedules of multiple solvers in ppfolio, which showed very impressive performance in the 2011 Satisfiability Testing (SAT) Competition. Inspired by this, we take advantage of the modeling and solving capacities of Answer Set Programming (ASP) to automatically determine more refined, that is, nonuniform and ordered solver schedules from the existing benchmarking data. We begin by formulating the determination of such schedules as multi-criteria optimization problems and provide corresponding ASP encodings. The resulting encodings are easily customizable for different settings, and the computation of optimum schedules can mostly be done in the blink of an eye, even when dealing with large runtime data sets stemming from many solvers on hundreds to thousands of instances. Also, the fact that our approach can be customized easily enabled us to swiftly adapt it to generate parallel schedules for multi-processor machines.
KW  - algorithm schedules
KW  - answer set programming
KW  - portfolio-based solving
Y1  - 2015
U6  - https://doi.org/10.1017/S1471068414000015
SN  - 1471-0684
SN  - 1475-3081
VL  - 15
SP  - 117
EP  - 142
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Lindauer, Marius
A1  - Hoos, Holger H.
A1  - Hutter, Frank
A1  - Schaub, Torsten H.
T1  - An automatically configured algorithm selector
JF  - The journal of artificial intelligence research
N2  - Algorithm selection (AS) techniques - which involve choosing from a set of algorithms the one expected to solve a given problem instance most efficiently - have substantially improved the state of the art in solving many prominent AI problems, such as SAT, CSP, ASP, MAXSAT and QBF. Although several AS procedures have been introduced, not too surprisingly, none of them dominates all others across all AS scenarios. Furthermore, these procedures have parameters whose optimal values vary across AS scenarios. This holds specifically for the machine learning techniques that form the core of current AS procedures, and for their hyperparameters. Therefore, to successfully apply AS to new problems, algorithms and benchmark sets, two questions need to be answered: (i) how to select an AS approach and (ii) how to set its parameters effectively. We address both of these problems simultaneously by using automated algorithm configuration. Specifically, we demonstrate that we can automatically configure claspfolio 2, which implements a large variety of different AS approaches and their respective parameters in a single, highly-parameterized algorithm framework. Our approach, dubbed AutoFolio, allows researchers and practitioners across a broad range of applications to exploit the combined power of many different AS methods. We demonstrate AutoFolio can significantly improve the performance of claspfolio 2 on 8 out of the 13 scenarios from the Algorithm Selection Library, leads to new state-of-the-art algorithm selectors for 7 of these scenarios, and matches state-of-the-art performance (statistically) on all other scenarios. Compared to the best single algorithm for each AS scenario, AutoFolio achieves average speedup factors between 1.3 and 15.4.
Y1  - 2015
SN  - 1076-9757
SN  - 1943-5037
VL  - 53
SP  - 745
EP  - 778
PB  - AI Access Foundation
CY  - Marina del Rey
ER  - 
TY  - JOUR
A1  - Videla, Santiago
A1  - Guziolowski, Carito
A1  - Eduati, Federica
A1  - Thiele, Sven
A1  - Gebser, Martin
A1  - Nicolas, Jacques
A1  - Saez-Rodriguez, Julio
A1  - Schaub, Torsten H.
A1  - Siegel, Anne
T1  - Learning Boolean logic models of signaling networks with ASP
JF  - Theoretical computer science
N2  - Boolean networks provide a simple yet powerful qualitative modeling approach in systems biology. However, manual identification of logic rules underlying the system being studied is in most cases out of reach. Therefore, automated inference of Boolean logical networks from experimental data is a fundamental question in this field. This paper addresses the problem consisting of learning from a prior knowledge network describing causal interactions and phosphorylation activities at a pseudo-steady state, Boolean logic models of immediate-early response in signaling transduction networks. The underlying optimization problem has been so far addressed through mathematical programming approaches and the use of dedicated genetic algorithms. In a recent work we have shown severe limitations of stochastic approaches in this domain and proposed to use Answer Set Programming (ASP), considering a simpler problem setting. Herein, we extend our previous work in order to consider more realistic biological conditions including numerical datasets, the presence of feedback-loops in the prior knowledge network and the necessity of multi-objective optimization. In order to cope with such extensions, we propose several discretization schemes and elaborate upon our previous ASP encoding. Towards real-world biological data, we evaluate the performance of our approach over in silico numerical datasets based on a real and large-scale prior knowledge network. The correctness of our encoding and discretization schemes are dealt with in Appendices A-B. (C) 2014 Elsevier B.V. All rights reserved.
KW  - Answer set programming
KW  - Signaling transduction networks
KW  - Boolean logic models
KW  - Combinatorial multi-objective optimization
KW  - Systems biology
Y1  - 2015
U6  - https://doi.org/10.1016/j.tcs.2014.06.022
SN  - 0304-3975
SN  - 1879-2294
VL  - 599
SP  - 79
EP  - 101
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Hoos, Holger
A1  - Lindauer, Marius
A1  - Schaub, Torsten H.
T1  - claspfolio 2
BT  - advances in algorithm selection for answer set programming
JF  - Theory and practice of logic programming
N2  - Building on the award-winning, portfolio-based ASP solver claspfolio, we present claspfolio 2, a modular and open solver architecture that integrates several different portfolio-based algorithm selection approaches and techniques. The claspfolio 2 solver framework supports various feature generators, solver selection approaches, solver portfolios, as well as solver-schedule-based pre-solving techniques. The default configuration of claspfolio 2 relies on a light-weight version of the ASP solver clasp to generate static and dynamic instance features. The flexible open design of claspfolio 2 is a distinguishing factor even beyond ASP. As such, it provides a unique framework for comparing and combining existing portfolio-based algorithm selection approaches and techniques in a single, unified framework. Taking advantage of this, we conducted an extensive experimental study to assess the impact of different feature sets, selection approaches and base solver portfolios. In addition to gaining substantial insights into the utility of the various approaches and techniques, we identified a default configuration of claspfolio 2 that achieves substantial performance gains not only over clasp's default configuration and the earlier version of claspfolio, but also over manually tuned configurations of clasp.
Y1  - 2014
U6  - https://doi.org/10.1017/S1471068414000210
SN  - 1471-0684
SN  - 1475-3081
VL  - 14
SP  - 569
EP  - 585
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Sabuncu, Orkunt
A1  - Schaub, Torsten H.
T1  - An incremental answer set programming based system for finite model computation
JF  - AI communications : AICOM ; the European journal on artificial intelligence
N2  - We address the problem of Finite Model Computation (FMC) of first-order theories and show that FMC can efficiently and transparently be solved by taking advantage of a recent extension of Answer Set Programming (ASP), called incremental Answer Set Programming (iASP). The idea is to use the incremental parameter in iASP programs to account for the domain size of a model. The FMC problem is then successively addressed for increasing domain sizes until an answer set, representing a finite model of the original first-order theory, is found. We implemented a system based on the iASP solver iClingo and demonstrate its competitiveness by showing that it slightly outperforms the winner of the FNT division of CADE's 2009 Automated Theorem Proving (ATP) competition on the respective benchmark collection.
KW  - Incremental answer set programming
KW  - finite model computation
Y1  - 2011
U6  - https://doi.org/10.3233/AIC-2011-0496
SN  - 0921-7126
VL  - 24
IS  - 2
SP  - 195
EP  - 212
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Kaufmann, Benjamin
A1  - Kaminski, Roland
A1  - Ostrowski, Max
A1  - Schaub, Torsten H.
A1  - Schneider, Marius
T1  - Potassco the Potsdam answer set solving collection
JF  - AI communications : AICOM ; the European journal on artificial intelligence
N2  - This paper gives an overview of the open source project Potassco, the Potsdam Answer Set Solving Collection, bundling tools for Answer Set Programming developed at the University of Potsdam.
KW  - Answer set programming
KW  - declarative problem solving
Y1  - 2011
U6  - https://doi.org/10.3233/AIC-2011-0491
SN  - 0921-7126
VL  - 24
IS  - 2
SP  - 107
EP  - 124
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Schaub, Torsten H.
A1  - Thiele, Sven
A1  - Veber, Philippe
T1  - Detecting inconsistencies in large biological networks with answer set programming
JF  - Theory and practice of logic programming
N2  - We introduce an approach to detecting inconsistencies in large biological networks by using answer set programming. To this end, we build upon a recently proposed notion of consistency between biochemical/genetic reactions and high-throughput profiles of cell activity. We then present an approach based on answer set programming to check the consistency of large-scale data sets. Moreover, we extend this methodology to provide explanations for inconsistencies by determining minimal representations of conflicts. In practice, this can be used to identify unreliable data or to indicate missing reactions.
KW  - answer set programming
KW  - bioinformatics
KW  - consistency
KW  - diagnosis
Y1  - 2011
U6  - https://doi.org/10.1017/S1471068410000554
SN  - 1471-0684
VL  - 11
IS  - 5-6
SP  - 323
EP  - 360
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Kaminski, Roland
A1  - Schaub, Torsten H.
T1  - Complex optimization in answer set programming
JF  - Theory and practice of logic programming
N2  - Preference handling and optimization are indispensable means for addressing nontrivial applications in Answer Set Programming (ASP). However, their implementation becomes difficult whenever they bring about a significant increase in computational complexity. As a consequence, existing ASP systems do not offer complex optimization capacities, supporting, for instance, inclusion-based minimization or Pareto efficiency. Rather, such complex criteria are typically addressed by resorting to dedicated modeling techniques, like saturation. Unlike the ease of common ASP modeling, however, these techniques are rather involved and hardly usable by ASP laymen. We address this problem by developing a general implementation technique by means of meta-prpogramming, thus reusing existing ASP systems to capture various forms of qualitative preferences among answer sets. In this way, complex preferences and optimization capacities become readily available for ASP applications.
KW  - Answer Set Programming
KW  - Preference Handling
KW  - Complex optimization
KW  - Meta-Programming
Y1  - 2011
U6  - https://doi.org/10.1017/S1471068411000329
SN  - 1471-0684
VL  - 11
IS  - 3
SP  - 821
EP  - 839
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Durzinsky, Markus
A1  - Marwan, Wolfgang
A1  - Ostrowski, Max
A1  - Schaub, Torsten H.
A1  - Wagler, Annegret
T1  - Automatic network reconstruction using ASP
JF  - Theory and practice of logic programming
N2  - Building biological models by inferring functional dependencies from experimental data is an important issue in Molecular Biology. To relieve the biologist from this traditionally manual process, various approaches have been proposed to increase the degree of automation. However, available approaches often yield a single model only, rely on specific assumptions, and/or use dedicated, heuristic algorithms that are intolerant to changing circumstances or requirements in the view of the rapid progress made in Biotechnology. Our aim is to provide a declarative solution to the problem by appeal to Answer Set Programming (ASP) overcoming these difficulties. We build upon an existing approach to Automatic Network Reconstruction proposed by part of the authors. This approach has firm mathematical foundations and is well suited for ASP due to its combinatorial flavor providing a characterization of all models explaining a set of experiments. The usage of ASP has several benefits over the existing heuristic algorithms. First, it is declarative and thus transparent for biological experts. Second, it is elaboration tolerant and thus allows for an easy exploration and incorporation of biological constraints. Third, it allows for exploring the entire space of possible models. Finally, our approach offers an excellent performance, matching existing, special-purpose systems.
Y1  - 2011
U6  - https://doi.org/10.1017/S1471068411000287
SN  - 1471-0684
VL  - 11
SP  - 749
EP  - 766
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Mileo, Alessandra
A1  - Schaub, Torsten H.
A1  - Merico, Davide
A1  - Bisiani, Roberto
T1  - Knowledge-based multi-criteria optimization to support indoor positioning
JF  - Annals of mathematics and artificial intelligence
N2  - Indoor position estimation constitutes a central task in home-based assisted living environments. Such environments often rely on a heterogeneous collection of low-cost sensors whose diversity and lack of precision has to be compensated by advanced techniques for localization and tracking. Although there are well established quantitative methods in robotics and neighboring fields for addressing these problems, they lack advanced knowledge representation and reasoning capacities. Such capabilities are not only useful in dealing with heterogeneous and incomplete information but moreover they allow for a better inclusion of semantic information and more general homecare and patient-related knowledge. We address this problem and investigate how state-of-the-art localization and tracking methods can be combined with Answer Set Programming, as a popular knowledge representation and reasoning formalism. We report upon a case-study and provide a first experimental evaluation of knowledge-based position estimation both in a simulated as well as in a real setting.
KW  - Knowledge representation
KW  - Answer Set Programming
KW  - Wireless Sensor Networks
KW  - Localization
KW  - Tracking
Y1  - 2011
U6  - https://doi.org/10.1007/s10472-011-9241-2
SN  - 1012-2443
SN  - 1573-7470
VL  - 62
IS  - 3-4
SP  - 345
EP  - 370
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Kaufmann, Benjamin
A1  - Schaub, Torsten H.
T1  - Multi-threaded ASP solving with clasp
JF  - Theory and practice of logic programming
N2  - We present the new multi-threaded version of the state-of-the-art answer set solver clasp. We detail its component and communication architecture and illustrate how they support the principal functionalities of clasp. Also, we provide some insights into the data representation used for different constraint types handled by clasp. All this is accompanied by an extensive experimental analysis of the major features related to multi-threading in clasp.
Y1  - 2012
U6  - https://doi.org/10.1017/S1471068412000166
SN  - 1471-0684
VL  - 12
IS  - 8
SP  - 525
EP  - 545
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Ostrowski, Max
A1  - Schaub, Torsten H.
T1  - ASP modulo CSP The clingcon system
JF  - Theory and practice of logic programming
N2  - We present the hybrid ASP solver clingcon, combining the simple modeling language and the high performance Boolean solving capacities of Answer Set Programming (ASP) with techniques for using non-Boolean constraints from the area of Constraint Programming (CP). The new clingcon system features an extended syntax supporting global constraints and optimize statements for constraint variables. The major technical innovation improves the interaction between ASP and CP solver through elaborated learning techniques based on irreducible inconsistent sets. A broad empirical evaluation shows that these techniques yield a performance improvement of an order of magnitude.
Y1  - 2012
U6  - https://doi.org/10.1017/S1471068412000142
SN  - 1471-0684
VL  - 12
SP  - 485
EP  - 503
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Kaufmann, Benjamin
A1  - Schaub, Torsten H.
T1  - Conflict-driven answer set solving: From theory to practice
JF  - Artificial intelligence
N2  - We introduce an approach to computing answer sets of logic programs, based on concepts successfully applied in Satisfiability (SAT) checking. The idea is to view inferences in Answer Set Programming (ASP) as unit propagation on nogoods. This provides us with a uniform constraint-based framework capturing diverse inferences encountered in ASP solving. Moreover, our approach allows us to apply advanced solving techniques from the area of SAT. As a result, we present the first full-fledged algorithmic framework for native conflict-driven ASP solving. Our approach is implemented in the ASP solver clasp that has demonstrated its competitiveness and versatility by winning first places at various solver contests.
KW  - Answer set programming
KW  - Logic programming
KW  - Nonmonotonic reasoning
Y1  - 2012
U6  - https://doi.org/10.1016/j.artint.2012.04.001
SN  - 0004-3702
VL  - 187
IS  - 8
SP  - 52
EP  - 89
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Schaub, Torsten H.
T1  - Tableau calculi for logic programs under answer set semantics
JF  - ACM transactions on computational logic
N2  - We introduce formal proof systems based on tableau methods for analyzing computations in Answer Set Programming (ASP). Our approach furnishes fine-grained instruments for characterizing operations as well as strategies of ASP solvers. The granularity is detailed enough to capture a variety of propagation and choice methods of algorithms used for ASP solving, also incorporating SAT-based and conflict-driven learning approaches to some extent. This provides us with a uniform setting for identifying and comparing fundamental properties of ASP solving approaches. In particular, we investigate their proof complexities and show that the run-times of best-case computations can vary exponentially between different existing ASP solvers. Apart from providing a framework for comparing ASP solving approaches, our characterizations also contribute to their understanding by pinning down the constitutive atomic operations. Furthermore, our framework is flexible enough to integrate new inference patterns, and so to study their relation to existing ones. To this end, we generalize our approach and provide an extensible basis aiming at a modular incorporation of additional language constructs. This is exemplified by augmenting our basic tableau methods with cardinality constraints and disjunctions.
KW  - Theory
KW  - Answer Set Programming
KW  - tableau calculi
KW  - proof complexity
Y1  - 2013
U6  - https://doi.org/10.1145/2480759.2480767
SN  - 1529-3785
VL  - 14
IS  - 2
PB  - Association for Computing Machinery
CY  - New York
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  - Banbara, Mutsunori
A1  - Soh, Takehide
A1  - Tamura, Naoyuki
A1  - Inoue, Katsumi
A1  - Schaub, Torsten H.
T1  - Answer set programming as a modeling language for course timetabling
JF  - Theory and practice of logic programming
N2  - The course timetabling problem can be generally defined as the task of assigning a number of lectures to a limited set of timeslots and rooms, subject to a given set of hard and soft constraints. The modeling language for course timetabling is required to be expressive enough to specify a wide variety of soft constraints and objective functions. Furthermore, the resulting encoding is required to be extensible for capturing new constraints and for switching them between hard and soft, and to be flexible enough to deal with different formulations. In this paper, we propose to make effective use of ASP as a modeling language for course timetabling. We show that our ASP-based approach can naturally satisfy the above requirements, through an ASP encoding of the curriculum-based course timetabling problem proposed in the third track of the second international timetabling competition (ITC-2007). Our encoding is compact and human-readable, since each constraint is individually expressed by either one or two rules. Each hard constraint is expressed by using integrity constraints and aggregates of ASP. Each soft constraint S is expressed by rules in which the head is the form of penalty (S, V, C), and a violation V and its penalty cost C are detected and calculated respectively in the body. We carried out experiments on four different benchmark sets with five different formulations. We succeeded either in improving the bounds or producing the same bounds for many combinations of problem instances and formulations, compared with the previous best known bounds.
KW  - answer set programming
KW  - educational timetabling
KW  - course timetabling
Y1  - 2013
U6  - https://doi.org/10.1017/S1471068413000495
SN  - 1471-0684
VL  - 13
IS  - 2
SP  - 783
EP  - 798
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Kaminski, Roland
A1  - Schaub, Torsten H.
A1  - Siegel, Anne
A1  - Videla, Santiago
T1  - Minimal intervention strategies in logical signaling networks with ASP
JF  - Theory and practice of logic programming
N2  - Proposing relevant perturbations to biological signaling networks is central to many problems in biology and medicine because it allows for enabling or disabling certain biological outcomes. In contrast to quantitative methods that permit fine-grained (kinetic) analysis, qualitative approaches allow for addressing large-scale networks. This is accomplished by more abstract representations such as logical networks. We elaborate upon such a qualitative approach aiming at the computation of minimal interventions in logical signaling networks relying on Kleene's three-valued logic and fixpoint semantics. We address this problem within answer set programming and show that it greatly outperforms previous work using dedicated algorithms.
Y1  - 2013
U6  - https://doi.org/10.1017/S1471068413000422
SN  - 1471-0684
VL  - 13
SP  - 675
EP  - 690
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Gharib, Mona
A1  - Schaub, Torsten H.
A1  - Mercer, Robert E.
T1  - Incremental answer set programming : a preliminary report
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Hermenegildo, Manuel
A1  - Schaub, Torsten H.
T1  - Introduction to the technical communications of the 26th International Conference on Logic Programming : special issue
Y1  - 2010
UR  - http://www.cs.kuleuven.ac.be/~dtai/projects/ALP//TPLP/
U6  - https://doi.org/10.1017/S1471068410000153
SN  - 1471-0684
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Gharib, Mona
A1  - Mercer, Robert E.
A1  - Schaub, Torsten H.
T1  - Monotonic answer set programming
N2  - Answer set programming (ASP) does not allow for incrementally constructing answer sets or locally validating constructions like proofs by only looking at a part of the given program. In this article, we elaborate upon an alternative approach to ASP that allows for incremental constructions. Our approach draws its basic intuitions from the area of default logics. We investigate the feasibility of the concept of semi-monotonicity known from default logics as a basis of incrementality. On the one hand, every logic program has at least one answer set in our alternative setting, which moreover can be constructed incrementally based on generating rules. On the other hand, the approach may produce answer sets lacking characteristic properties of standard answer sets, such as being a model of the given program. We show how integrity constraints can be used to re-establish such properties, even up to correspondence with standard answer sets. Furthermore, we develop an SLD-like proof procedure for our incremental approach to ASP, which allows for query-oriented computations. Also, we provide a characterization of our definition of answer sets via a modification of Clarks completion. Based on this notion of program completion, we present an algorithm for computing the answer sets of a logic program in our approach.
Y1  - 2009
UR  - http://logcom.oxfordjournals.org/
U6  - https://doi.org/10.1093/logcom/exn040
SN  - 0955-792X
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
A1  - Tompits, Hans
T1  - A general framework for expressing preferences in causal reasoning and planning
N2  - We consider the problem of representing arbitrary preferences in causal reasoning and planning systems. In planning, a preference may be seen as a goal or constraint that is desirable, but not necessary, to satisfy. To begin, we define a very general query language for histories, or interleaved sequences of world states and actions. Based on this, we specify a second language in which preferences are defined. A single preference defines a binary relation on histories, indicating that one history is preferred to the other. From this, one can define global preference orderings on the set of histories, the maximal elements of which are the preferred histories. The approach is very general and flexible; thus it constitutes a base language in terms of which higher-level preferences may be defined. To this end, we investigate two fundamental types of preferences that we call choice and temporal preferences. We consider concrete strategies for these types of preferences and encode them in terms of our framework. We suggest how to express aggregates in the approach, allowing, e.g. the expression of a preference for histories with lowest total action costs. Last, our approach can be used to express other approaches and so serves as a common framework in which such approaches can be expressed and compared. We illustrate this by indicating how an approach due to Son and Pontelli can be encoded in our approach, as well as the language PDDL3.
Y1  - 2007
UR  - http://logcom.oxfordjournals.org/
U6  - https://doi.org/10.1093/logcom/exm046
SN  - 0955-792X
ER  - 
TY  - JOUR
A1  - Brain, Martin
A1  - Faber, Wolfgang
A1  - Maratea, Marco
A1  - Polleres, Axel
A1  - Schaub, Torsten H.
A1  - Schindlauer, Roman
T1  - What should an ASP solver output? : a multiple position paper
Y1  - 2007
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  - 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  - 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  - Clasp : a conflict-driven answer set solver
Y1  - 2007
SN  - 978-3-540- 72199-4
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  - 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  - Gebser, Martin
A1  - Schaub, Torsten H.
T1  - Generic tableaux for answer set programming
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Gharib, Mona
A1  - Schaub, Torsten H.
T1  - Incremental answer sets and their computation
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  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten H.
T1  - A context-based framework for default logics
Y1  - 1993
SN  - 0-262-51071-5
ER  - 
TY  - JOUR
A1  - Thielscher, Michael
A1  - Schaub, Torsten H.
T1  - Default reasoning by deductive planning
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten H.
T1  - An approach to context-based default reasoning
Y1  - 1995
SN  - 0169-2968
ER  - 
TY  - JOUR
A1  - Linke, Thomas
A1  - Schaub, Torsten H.
T1  - Lemma handling in default logic theorem provers
Y1  - 1995
SN  - 3540601120
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  - 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  - 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  - 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  - Brüning, Stefan
T1  - Prolog technology for default reasoning
Y1  - 1996
SN  - 0-471-96809-9
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  - Besnard, Philippe
A1  - Schaub, Torsten H.
T1  - Circumscribing inconsistency
Y1  - 1997
SN  - 1-558-60480-4
SN  - 1045-0823
ER  - 
TY  - JOUR
A1  - Linke, Thomas
A1  - Schaub, Torsten H.
T1  - Towards a classification of default logic
Y1  - 1997
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  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
T1  - Compiling reasoning with and about preferences into default logic
Y1  - 1997
SN  - 1-558-60480-4
SN  - 1045-0823
ER  - 
TY  - JOUR
A1  - Schaub, Torsten H.
A1  - Nicolas, Pascal
T1  - An implementation platform for query-answering in default logics : theoretical underpinnings
Y1  - 1997
SN  - 3-540-63614-5
ER  - 
TY  - JOUR
A1  - Schaub, Torsten H.
A1  - Nicolas, Pascal
T1  - An implementation platform for query-answering in default logics : the XRay system, its implementation and evaluation
Y1  - 1997
SN  - 3-540-63255-7
ER  - 
TY  - JOUR
A1  - Benhammadi, Farid
A1  - Nicolas, Pascal
A1  - Schaub, Torsten H.
T1  - Extension calculus and query answering in prioritized default logic
Y1  - 1998
SN  - 3-540-64993-X
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  - Reasoning with sets of preferences in default logic
Y1  - 1998
SN  - 3-540- 65271-x
ER  - 
TY  - JOUR
A1  - Schaub, Torsten H.
T1  - The family of default logics
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten H.
T1  - Signed systems for paraconsistent reasoning
Y1  - 1998
SN  - 0168-7433
ER  - 
TY  - JOUR
A1  - Schaub, Torsten H.
A1  - Brüning, Stefan
T1  - Prolog technology for default reasoning : proof theory and compilation techniques
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Benhammadi, Farid
A1  - Nicolas, Pascal
A1  - Schaub, Torsten H.
T1  - Extension calculus and query answering in prioritized default logic
Y1  - 1998
SN  - 3-540- 64993-X
ER  - 
TY  - JOUR
A1  - Linke, Thomas
A1  - Schaub, Torsten H.
T1  - An approach to query-answering in Reiter's default logic and the underlying existence of extensions problem.
Y1  - 1998
SN  - 3-540-65141-1
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten H.
T1  - Characterization of non-monotone non-constructive systems
Y1  - 1998
SN  - 1012-2443
ER  - 
TY  - JOUR
A1  - Nicolas, Pascal
A1  - Schaub, Torsten H.
T1  - The XRay system : an implementation platform for local query-answering in default logics
Y1  - 1998
SN  - 3-540-65312-0
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten H.
T1  - Signed systems for paraconsistent reasoning
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Linke, Thomas
A1  - Schaub, Torsten H.
T1  - On bottom-up pre-processing techniques for automated default reasoning
Y1  - 1999
SN  - 3-540-66131-x
ER  - 
TY  - JOUR
A1  - Brüning, Stefan
A1  - Schaub, Torsten H.
T1  - A voiding non-ground variables
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Benhammadi, Farid
A1  - Nicolas, Pascal
A1  - Schaub, Torsten H.
T1  - Query-answering in prioritized default logic
Y1  - 1999
SN  - 3-540-66131-X
ER  - 
TY  - JOUR
A1  - Benhammadi, Farid
A1  - Nicolas, Pascal
A1  - Schaub, Torsten H.
T1  - Query-answering in prioritized default logic
Y1  - 1999
SN  - 3-540-66131-X
ER  - 
TY  - JOUR
A1  - Brüning, Stefan
A1  - Schaub, Torsten H.
T1  - Avoiding non-ground variables
Y1  - 1999
SN  - 3-540-66131-x
ER  - 
TY  - BOOK
A1  - Schaub, Torsten H.
T1  - The automation of reasoning with incomplete information : from semantic foundations to efficient computation
T3  - Lecture notes in computer science
Y1  - 1999
SN  - 3-540-64515-2
U6  - https://doi.org/10.1007/BFb0054963
VL  - 1409
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Brüning, Stefan
A1  - Schaub, Torsten H.
T1  - A connection calculus for handling incomplete information
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
T1  - A consistency-based model for belief change: preliminary report
Y1  - 2000
UR  - http://xxx.lanl.gov/abs/cs.AI/0003052
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
A1  - Tompits, Hans
T1  - A compiler for ordered logic programs
Y1  - 2000
UR  - http://arxiv.org/abs/cs.AI/0003024
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
A1  - Tompits, Hans
T1  - Logic programs with compiled preferences
Y1  - 2000
UR  - http://xxx.lanl.gov/abs/cs.AI/0003028
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
A1  - Tompits, Hans
T1  - Logic programs with compiled preferences
Y1  - 2000
SN  - 1-58603-013-2
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
T1  - A consistency-based model for belief change: preliminary report
Y1  - 2000
SN  - 0-262-51112-6
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
A1  - Tompits, Hans
T1  - A compilation of Brewka and Eiter's approach to prioritizationtion
Y1  - 2000
SN  - 3-540-41131-3
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
T1  - Expressing preferences in default logic
Y1  - 2000
SN  - 0004-3702
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
T1  - The role of default logic in knowledge representation
Y1  - 2000
SN  - 0-7923-7224-7
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten H.
T1  - What is a (non-constructive) non-monotone logical system?
Y1  - 2000
SN  - 0304-3975
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten H.
T1  - Significant inferences
Y1  - 2000
SN  - 1-55860-690-4
ER  - 
TY  - JOUR
A1  - Linke, Thomas
A1  - Schaub, Torsten H.
T1  - Alternative foundations for Reiter's default logic.
Y1  - 2000
SN  - 0004-3702
ER  - 
TY  - JOUR
A1  - Schaub, Torsten H.
A1  - Wang, Kewen
T1  - A comparative study of logic programs with preference
Y1  - 2001
SN  - 1-558-60777-3
SN  - 1045-0823
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
A1  - Tompits, Hans
T1  - A generic compiler for ordered logic programs
Y1  - 2001
SN  - 3-540-42593-4
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
T1  - How to reason credulously and skeptically within a single extension.
Y1  - 2001
SN  - 3-540- 42464-4
ER  - 
TY  - JOUR
A1  - Schaub, Torsten H.
A1  - Wang, Kewen
T1  - A comparative study of logic programs with preference
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
T1  - How to reason credulously and skeptically within a single extension
Y1  - 2001
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  - 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  - 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  - 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  - 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  - 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  - 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  - Delgrande, James Patrick
A1  - Schaub, Torsten H.
T1  - Reasoning credulously and skeptically within a single extension
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Fanselow, Gisbert
A1  - Schaub, Torsten H.
T1  - Optimality theory as a family of cumulative logics
Y1  - 2002
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  - 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  - 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 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.
A1  - Wang, Kewen
T1  - A semantic framework for prefernce handling in answer set programming
Y1  - 2003
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  - Besnard, Philippe
A1  - Mercer, Robert E.
A1  - Schaub, Torsten H.
T1  - Optimality theory throught default logic
Y1  - 2003
SN  - 3-540-20059-2
ER  -