TY  - JOUR
A1  - Bibel, Wolfgang
A1  - Brüning, Stefan
A1  - Otten, Jens
A1  - Rath, Thomas
A1  - Schaub, Torsten
T1  - Compressions and extensions
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten
T1  - Characterization of non-monotone non-constructive systems
Y1  - 1998
SN  - 1012-2443
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten
T1  - Signed systems for paraconsistent reasoning
Y1  - 1998
SN  - 0168-7433
ER  - 
TY  - JOUR
A1  - Schaub, Torsten
A1  - Brüning, Stefan
T1  - Prolog technology for default reasoning : proof theory and compilation techniques
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Schaub, Torsten
T1  - The family of default logics
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Delgrande, James
A1  - Schaub, Torsten
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  - Delgrande, James Patrick
A1  - Schaub, Torsten
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  - Gebser, Martin
A1  - Schaub, Torsten
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
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  - Gebser, Martin
A1  - Gharib, Mona
A1  - Mercer, Robert E.
A1  - Schaub, Torsten
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  - Gebser, Martin
A1  - Kaufmann, Benjamin
A1  - Schaub, Torsten
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  - Hermenegildo, Manuel
A1  - Schaub, Torsten
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  - Delgrande, James Patrick
A1  - Liu, Daphne H.
A1  - Schaub, Torsten
A1  - Thiele, Sven
T1  - COBA 2.0 : a consistency-based belief change system
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Gharib, Mona
A1  - Schaub, Torsten
A1  - Mercer, Robert E.
T1  - Incremental answer set programming : a preliminary report
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten
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  - Konczak, Kathrin
A1  - Linke, Thomas
A1  - Schaub, Torsten
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  - Anger, Christian
A1  - Gebser, Martin
A1  - Schaub, Torsten
T1  - Approaching the core of unfounded sets
Y1  - 2006
UR  - http://www.cs.uni-potsdam.de/wv/pdfformat/angesc06a.pdf
ER  - 
TY  - JOUR
A1  - Mileo, Alessandra
A1  - Schaub, Torsten
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  - Schaub, Torsten
A1  - Tompits, Hans
T1  - A preference-based framework for updating logic programs
Y1  - 2007
SN  - 978-3-540- 72199-4
ER  - 
TY  - JOUR
A1  - Gressmann, Jean
A1  - Janhunen, Tomi
A1  - Mercer, Robert E.
A1  - Schaub, Torsten
A1  - Thiele, Sven
A1  - Tichy, Richard
T1  - On probing and multi-threading in platypus
Y1  - 2006
ER  - 
TY  - JOUR
A1  - Grell, Susanne
A1  - Schaub, Torsten
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  - Gerbser, Martin
A1  - Schaub, Torsten
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  - Gerbser, Martin
A1  - Schaub, Torsten
T1  - Characterizing (ASP) inferences by unit propagation
Y1  - 2006
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten
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  - Flöter, André
A1  - Nicolas, Jacques
A1  - Schaub, Torsten
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  - Gharib, Mona
A1  - Mercer, Robert E.
A1  - Risch, V.
A1  - Schaub, Torsten
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  - Delgrande, James Patrick
A1  - Schaub, Torsten
T1  - On the relation between Reiterïs default logic and its (major) variants
Y1  - 2003
SN  - 3-540- 409494-5
ER  - 
TY  - JOUR
A1  - Konczak, Kathrin
A1  - Schaub, Torsten
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  - Besnard, Philippe
A1  - Mercer, Robert E.
A1  - Schaub, Torsten
T1  - Optimality theory throught default logic
Y1  - 2003
SN  - 3-540-20059-2
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten
A1  - Tompits, Hans
T1  - A framework for compiling preferences in logic programs
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten
T1  - Reasoning credulously and skeptically within a single extension
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Schaub, Torsten
A1  - Wang, Kewen
T1  - A semantic framework for prefernce handling in answer set programming
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Benhammadi, Farid
A1  - Nicolas, Pascal
A1  - Schaub, Torsten
T1  - Query-answering in prioritized default logic
Y1  - 1999
SN  - 3-540-66131-X
ER  - 
TY  - JOUR
A1  - Linke, Thomas
A1  - Schaub, Torsten
T1  - On bottom-up pre-processing techniques for automated default reasoning
Y1  - 1999
SN  - 3-540-66131-x
ER  - 
TY  - JOUR
A1  - Benhammadi, Farid
A1  - Nicolas, Pascal
A1  - Schaub, Torsten
T1  - Query-answering in prioritized default logic
Y1  - 1999
SN  - 3-540-66131-X
ER  - 
TY  - JOUR
A1  - Brüning, Stefan
A1  - Schaub, Torsten
T1  - Avoiding non-ground variables
Y1  - 1999
SN  - 3-540-66131-x
ER  - 
TY  - JOUR
A1  - Nicolas, Pascal
A1  - Schaub, Torsten
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  - Brüning, Stefan
A1  - Schaub, Torsten
T1  - A voiding non-ground variables
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten
T1  - Signed systems for paraconsistent reasoning
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Brain, Martin
A1  - Gebser, Martin
A1  - Pührer, Jörg
A1  - Schaub, Torsten
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  - Kaufmann, Benjamin
A1  - Neumann, André
A1  - Schaub, Torsten
T1  - Conflict-driven answer set enumeration
Y1  - 2007
SN  - 978-3-540- 72199-4
ER  - 
TY  - JOUR
A1  - Linke, Thomas
A1  - Schaub, Torsten
T1  - Putting default logics in perspective
Y1  - 1996
SN  - 3-540-61708-6
ER  - 
TY  - JOUR
A1  - Linke, Thomas
A1  - Schaub, Torsten
T1  - Lemma handling in default logic theorem provers
Y1  - 1995
SN  - 3540601120
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Kaufmann, Benjamin
A1  - Neumann, André
A1  - Schaub, Torsten
T1  - Conflict-driven answer set solving
Y1  - 2007
SN  - 978-1-57735-323-2
ER  - 
TY  - JOUR
A1  - Besnard, Philippe
A1  - Schaub, Torsten
T1  - A context-based framework for default logics
Y1  - 1993
SN  - 0-262-51071-5
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Gharib, Mona
A1  - Schaub, Torsten
T1  - Incremental answer sets and their computation
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Gebser, Martin
A1  - Schaub, Torsten
T1  - Generic tableaux for answer set programming
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Delgrande, James Patrick
A1  - Schaub, Torsten
T1  - A consistency-based framework for merging knowledge bases
Y1  - 2007
SN  - 1570-8683
ER  - 
TY  - JOUR
A1  - Konczak, Kathrin
A1  - Linke, Thomas
A1  - Schaub, Torsten
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  - Gressmann, Jean
A1  - Janhunen, Tomi
A1  - Mercer, Robert E.
A1  - Schaub, Torsten
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  -