@article{AngerGebserJanhunenetal.2006, author = {Anger, Christian and Gebser, Martin and Janhunen, Tomi and Schaub, Torsten H.}, title = {What's a head without a body?}, year = {2006}, language = {en} } @article{AngerGebserLinkeetal.2005, author = {Anger, Christian and Gebser, Martin and Linke, Thomas and Neumann, Andre and Schaub, Torsten H.}, title = {The nomore++ approach to answer set solving}, year = {2005}, language = {en} } @article{AngerGebserLinkeetal.2005, author = {Anger, Christian and Gebser, Martin and Linke, Thomas and Neumann, Andre and Schaub, Torsten H.}, title = {The nomore++ approach to answer set solving}, year = {2005}, language = {en} } @article{AngerGebserSchaub2006, author = {Anger, Christian and Gebser, Martin and Schaub, Torsten H.}, title = {Approaching the core of unfounded sets}, year = {2006}, language = {en} } @article{AngerKonczakLinkeetal.2005, author = {Anger, Christian and Konczak, Kathrin and Linke, Thomas and Schaub, Torsten H.}, title = {A Glimpse of Answer Set Programming}, issn = {0170-4516}, year = {2005}, language = {en} } @article{BanbaraInoueKaufmannetal.2018, author = {Banbara, Mutsunori and Inoue, Katsumi and Kaufmann, Benjamin and Okimoto, Tenda and Schaub, Torsten H. and Soh, Takehide and Tamura, Naoyuki and Wanko, Philipp}, title = {teaspoon}, series = {Annals of operation research}, volume = {275}, journal = {Annals of operation research}, number = {1}, publisher = {Springer}, address = {Dordrecht}, issn = {0254-5330}, doi = {10.1007/s10479-018-2757-7}, pages = {3 -- 37}, year = {2018}, abstract = {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.}, language = {en} } @article{BanbaraSohTamuraetal.2013, author = {Banbara, Mutsunori and Soh, Takehide and Tamura, Naoyuki and Inoue, Katsumi and Schaub, Torsten H.}, title = {Answer set programming as a modeling language for course timetabling}, series = {Theory and practice of logic programming}, volume = {13}, journal = {Theory and practice of logic programming}, number = {2}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068413000495}, pages = {783 -- 798}, year = {2013}, abstract = {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.}, language = {en} } @article{BenhammadiNicolasSchaub1998, author = {Benhammadi, Farid and Nicolas, Pascal and Schaub, Torsten H.}, title = {Extension calculus and query answering in prioritized default logic}, isbn = {3-540-64993-X}, year = {1998}, language = {en} } @article{BenhammadiNicolasSchaub1998, author = {Benhammadi, Farid and Nicolas, Pascal and Schaub, Torsten H.}, title = {Extension calculus and query answering in prioritized default logic}, isbn = {3-540- 64993-X}, year = {1998}, language = {en} } @article{BenhammadiNicolasSchaub1999, author = {Benhammadi, Farid and Nicolas, Pascal and Schaub, Torsten H.}, title = {Query-answering in prioritized default logic}, isbn = {3-540-66131-X}, year = {1999}, language = {en} } @article{BenhammadiNicolasSchaub1999, author = {Benhammadi, Farid and Nicolas, Pascal and Schaub, Torsten H.}, title = {Query-answering in prioritized default logic}, isbn = {3-540-66131-X}, year = {1999}, language = {en} } @article{BesnardFanselowSchaub2002, author = {Besnard, Philippe and Fanselow, Gisbert and Schaub, Torsten H.}, title = {Optimality theory as a family of cumulative logics}, year = {2002}, language = {en} } @article{BesnardMercerSchaub2003, author = {Besnard, Philippe and Mercer, Robert E. and Schaub, Torsten H.}, title = {Optimality theory throught default logic}, isbn = {3-540-20059-2}, year = {2003}, language = {en} } @article{BesnardMercerSchaub2002, author = {Besnard, Philippe and Mercer, Robert E. and Schaub, Torsten H.}, title = {Optimality Theory via Default Logic}, year = {2002}, language = {en} } @article{BesnardSchaub1996, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {A simple signed system for paraconsistent reasoning}, isbn = {3-540-61630-6}, year = {1996}, language = {en} } @article{BesnardSchaub1993, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {A context-based framework for default logics}, isbn = {0-262-51071-5}, year = {1993}, language = {en} } @article{BesnardSchaub1998, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {Signed systems for paraconsistent reasoning}, year = {1998}, language = {en} } @article{BesnardSchaub1998, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {Characterization of non-monotone non-constructive systems}, issn = {1012-2443}, year = {1998}, language = {en} } @article{BesnardSchaub1998, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {Signed systems for paraconsistent reasoning}, issn = {0168-7433}, year = {1998}, language = {en} } @article{BesnardSchaub1995, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {An approach to context-based default reasoning}, issn = {0169-2968}, year = {1995}, language = {en} } @article{BesnardSchaub1997, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {Circumscribing inconsistency}, isbn = {1-558-60480-4}, issn = {1045-0823}, year = {1997}, language = {en} } @article{BesnardSchaub2000, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {Significant inferences}, isbn = {1-55860-690-4}, year = {2000}, language = {en} } @article{BesnardSchaub2000, author = {Besnard, Philippe and Schaub, Torsten H.}, title = {What is a (non-constructive) non-monotone logical system?}, issn = {0304-3975}, year = {2000}, language = {en} } @article{BesnardSchaubTompitsetal.2002, author = {Besnard, Philippe and Schaub, Torsten H. and Tompits, Hans and Woltran, Stefan}, title = {Paraconsistent reasoning via quantified boolean formulas}, isbn = {3-540-44190-5}, year = {2002}, language = {en} } @article{BesnardSchaubTompitsetal.2003, author = {Besnard, Philippe and Schaub, Torsten H. and Tompits, Hans and Woltran, Stefan}, title = {Paraconsistent reasoning via quantified boolean formulas : Part II: Circumscribing inconsistent theories}, isbn = {3-540- 409494-5}, year = {2003}, language = {en} } @article{BibelBrueningOttenetal.1998, author = {Bibel, Wolfgang and Br{\"u}ning, Stefan and Otten, Jens and Rath, Thomas and Schaub, Torsten H.}, title = {Compressions and extensions}, year = {1998}, language = {en} } @article{BoeselLinkeSchaub2004, author = {Boesel, Andreas and Linke, Thomas and Schaub, Torsten H.}, title = {Profiling answer set programming : the visualization component of the noMoRe System}, isbn = {3-540-23242-7}, year = {2004}, language = {en} } @article{BorchertAngerSchaubetal.2004, author = {Borchert, P. and Anger, Christian and Schaub, Torsten H. and Truszczynski, M.}, title = {Towards systematic benchmarking in answer set programming : the dagstuhl initiative}, isbn = {3-540- 20721-x}, year = {2004}, language = {en} } @article{BrainFaberMarateaetal.2007, author = {Brain, Martin and Faber, Wolfgang and Maratea, Marco and Polleres, Axel and Schaub, Torsten H. and Schindlauer, Roman}, title = {What should an ASP solver output? : a multiple position paper}, year = {2007}, language = {en} } @article{BrainGebserPuehreretal.2007, author = {Brain, Martin and Gebser, Martin and P{\"u}hrer, J{\"o}rg and Schaub, Torsten H. and Tompits, Hans and Woltran, Stefan}, title = {"That is illogical, Captain!" : the debugging support tool spock for answer-set programs ; system description}, year = {2007}, language = {en} } @article{BrainGebserPuehreretal.2007, author = {Brain, Martin and Gebser, Martin and P{\"u}hrer, J{\"o}rg and Schaub, Torsten H. and Tompits, Hans and Woltran, Stefan}, title = {Debugging ASP programs by means of ASP}, isbn = {978-3-540- 72199-4}, year = {2007}, language = {en} } @article{BrewkaEllmauthalerKernIsberneretal.2018, author = {Brewka, Gerhard and Ellmauthaler, Stefan and Kern-Isberner, Gabriele and Obermeier, Philipp and Ostrowski, Max and Romero, Javier and Schaub, Torsten H. and Schieweck, Steffen}, title = {Advanced solving technology for dynamic and reactive applications}, series = {K{\"u}nstliche Intelligenz}, volume = {32}, journal = {K{\"u}nstliche Intelligenz}, number = {2-3}, publisher = {Springer}, address = {Heidelberg}, issn = {0933-1875}, doi = {10.1007/s13218-018-0538-8}, pages = {199 -- 200}, year = {2018}, language = {en} } @article{BrueningSchaub1996, author = {Br{\"u}ning, Stefan and Schaub, Torsten H.}, title = {A model-based approach to consistency-checking}, isbn = {3-540-61286-6}, year = {1996}, language = {en} } @article{BrueningSchaub2000, author = {Br{\"u}ning, Stefan and Schaub, Torsten H.}, title = {A connection calculus for handling incomplete information}, year = {2000}, language = {en} } @article{BrueningSchaub1999, author = {Br{\"u}ning, Stefan and Schaub, Torsten H.}, title = {Avoiding non-ground variables}, isbn = {3-540-66131-x}, year = {1999}, language = {en} } @article{BrueningSchaub1999, author = {Br{\"u}ning, Stefan and Schaub, Torsten H.}, title = {A voiding non-ground variables}, year = {1999}, language = {en} } @article{CabalarDieguezSchaubetal.2020, author = {Cabalar, Pedro and Dieguez, Martin and Schaub, Torsten H. and Schuhmann, Anna}, title = {Towards metric temporal answer set programming}, series = {Theory and practice of logic programming}, volume = {20}, journal = {Theory and practice of logic programming}, number = {5}, publisher = {Cambridge Univ. Press}, address = {Cambridge [u.a.]}, issn = {1471-0684}, doi = {10.1017/S1471068420000307}, pages = {783 -- 798}, year = {2020}, abstract = {We elaborate upon the theoretical foundations of a metric temporal extension of Answer Set Programming. In analogy to previous extensions of ASP with constructs from Linear Temporal and Dynamic Logic, we accomplish this in the setting of the logic of Here-and-There and its non-monotonic extension, called Equilibrium Logic. More precisely, we develop our logic on the same semantic underpinnings as its predecessors and thus use a simple time domain of bounded time steps. This allows us to compare all variants in a uniform framework and ultimately combine them in a common implementation.}, language = {en} } @article{CabalarFandinnoGareaetal.2020, author = {Cabalar, Pedro and Fandinno, Jorge and Garea, Javier and Romero, Javier and Schaub, Torsten H.}, title = {Eclingo}, series = {Theory and practice of logic programming}, volume = {20}, journal = {Theory and practice of logic programming}, number = {6}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068420000228}, pages = {834 -- 847}, year = {2020}, abstract = {We describe eclingo, a solver for epistemic logic programs under Gelfond 1991 semantics built upon the Answer Set Programming system clingo. The input language of eclingo uses the syntax extension capabilities of clingo to define subjective literals that, as usual in epistemic logic programs, allow for checking the truth of a regular literal in all or in some of the answer sets of a program. The eclingo solving process follows a guess and check strategy. It first generates potential truth values for subjective literals and, in a second step, it checks the obtained result with respect to the cautious and brave consequences of the program. This process is implemented using the multi-shot functionalities of clingo. We have also implemented some optimisations, aiming at reducing the search space and, therefore, increasing eclingo 's efficiency in some scenarios. Finally, we compare the efficiency of eclingo with two state-of-the-art solvers for epistemic logic programs on a pair of benchmark scenarios and show that eclingo generally outperforms their obtained results.}, language = {en} } @article{CabalarFandinnoSchaubetal.2019, author = {Cabalar, Pedro and Fandinno, Jorge and Schaub, Torsten H. and Schellhorn, Sebastian}, title = {Gelfond-Zhang aggregates as propositional formulas}, series = {Artificial intelligence}, volume = {274}, journal = {Artificial intelligence}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0004-3702}, doi = {10.1016/j.artint.2018.10.007}, pages = {26 -- 43}, year = {2019}, abstract = {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.}, language = {en} } @article{DelgrandeGharibMerceretal.2003, author = {Delgrande, James Patrick and Gharib, Mona and Mercer, Robert E. and Risch, V. and Schaub, Torsten H.}, title = {Lukaszewicz-style answer set programming : a preliminary report}, issn = {1613-0073}, year = {2003}, language = {en} } @article{DelgrandeHunterSchaub2002, author = {Delgrande, James Patrick and Hunter, Anthony and Schaub, Torsten H.}, title = {COBA: a consistency-based belief revision system}, isbn = {3-540-44190-5}, year = {2002}, language = {en} } @article{DelgrandeLangSchaub2007, author = {Delgrande, James Patrick and Lang, J{\´e}r{\^o}me and Schaub, Torsten H.}, title = {Belief change based on global minimisation}, year = {2007}, language = {en} } @article{DelgrandeLiuSchaubetal.2006, author = {Delgrande, James Patrick and Liu, Daphne H. and Schaub, Torsten H. and Thiele, Sven}, title = {COBA 2.0 : a consistency-based belief change system}, year = {2006}, language = {en} } @article{DelgrandeLiuSchaubetal.2007, author = {Delgrande, James Patrick and Liu, Daphne H. and Schaub, Torsten H. and Thiele, Sven}, title = {COBA 2.0 : a consistency-based belief change system}, year = {2007}, language = {en} } @article{DelgrandeSchaub2005, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Expressing default logic variants in default logic}, issn = {0955-792X}, year = {2005}, abstract = {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}, language = {en} } @article{DelgrandeSchaub2004, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Two approaches to merging knowledge bases}, isbn = {3-540-23242-7}, year = {2004}, language = {en} } @article{DelgrandeSchaub2004, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Consistency-based approaches to merging knowledge based : preliminary report}, isbn = {92-990021-0-X}, year = {2004}, language = {en} } @article{DelgrandeSchaub2004, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Reasoning with sets of preferences in default logic}, issn = {0824-7935}, year = {2004}, abstract = {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}, language = {en} } @article{DelgrandeSchaub2003, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Reasoning credulously and skeptically within a single extension}, year = {2003}, language = {en} } @article{DelgrandeSchaub2003, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {On the relation between Reiter{\"i}s default logic and its (major) variants}, isbn = {3-540- 409494-5}, year = {2003}, language = {en} } @article{DelgrandeSchaub2003, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {A concictency-based paradigm for belief change}, issn = {0004-3702}, year = {2003}, language = {en} } @article{DelgrandeSchaub2002, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Reasoning credulously and skeptically within a single extension}, year = {2002}, language = {en} } @article{DelgrandeSchaub1997, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Compiling specificity into approaches to nonmonotonic reasoning}, issn = {0004-3702}, year = {1997}, language = {en} } @article{DelgrandeSchaub2007, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {A consistency-based framework for merging knowledge bases}, issn = {1570-8683}, year = {2007}, language = {en} } @article{DelgrandeSchaub1998, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Reasoning with sets of preferences in default logic}, isbn = {3-540- 65271-x}, year = {1998}, language = {en} } @article{DelgrandeSchaub1997, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Compiling reasoning with and about preferences into default logic}, isbn = {1-558-60480-4}, issn = {1045-0823}, year = {1997}, language = {en} } @article{DelgrandeSchaub2001, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {How to reason credulously and skeptically within a single extension.}, isbn = {3-540- 42464-4}, year = {2001}, language = {en} } @article{DelgrandeSchaub2001, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {How to reason credulously and skeptically within a single extension}, year = {2001}, language = {en} } @article{DelgrandeSchaub2000, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {The role of default logic in knowledge representation}, isbn = {0-7923-7224-7}, year = {2000}, language = {en} } @article{DelgrandeSchaub2000, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {Expressing preferences in default logic}, issn = {0004-3702}, year = {2000}, language = {en} } @article{DelgrandeSchaub2000, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {A consistency-based model for belief change: preliminary report}, isbn = {0-262-51112-6}, year = {2000}, language = {en} } @article{DelgrandeSchaub2000, author = {Delgrande, James Patrick and Schaub, Torsten H.}, title = {A consistency-based model for belief change: preliminary report}, year = {2000}, language = {en} } @article{DelgrandeSchaubTompits2006, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {A Preference-Based Framework for Updating logic Programs : preliminary reports}, year = {2006}, language = {en} } @article{DelgrandeSchaubTompits2007, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {A preference-based framework for updating logic programs}, isbn = {978-3-540- 72199-4}, year = {2007}, language = {en} } @article{DelgrandeSchaubTompits2006, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {An Extended Query language for action languages (and its application to aggregates and preferences)}, year = {2006}, language = {en} } @article{DelgrandeSchaubTompits2004, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {Domain-specific preference for causal reasoning and planning}, isbn = {1-577-35201-7}, year = {2004}, language = {en} } @article{DelgrandeSchaubTompits2003, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {A framework for compiling preferences in logic programs}, year = {2003}, language = {en} } @article{DelgrandeSchaubTompits2007, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {A general framework for expressing preferences in causal reasoning and planning}, issn = {0955-792X}, doi = {10.1093/logcom/exm046}, year = {2007}, abstract = {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.}, language = {en} } @article{DelgrandeSchaubTompits2001, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {A generic compiler for ordered logic programs}, isbn = {3-540-42593-4}, year = {2001}, language = {en} } @article{DelgrandeSchaubTompits2000, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {A compilation of Brewka and Eiter's approach to prioritizationtion}, isbn = {3-540-41131-3}, year = {2000}, language = {en} } @article{DelgrandeSchaubTompits2000, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {Logic programs with compiled preferences}, isbn = {1-58603-013-2}, year = {2000}, language = {en} } @article{DelgrandeSchaubTompits2000, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {Logic programs with compiled preferences}, year = {2000}, language = {en} } @article{DelgrandeSchaubTompits2000, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans}, title = {A compiler for ordered logic programs}, year = {2000}, language = {en} } @article{DelgrandeSchaubTompitsetal.2004, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans and Wang, Kewen}, title = {A classification and survey of preference handling approchaches in nonmonotonic reasoning}, issn = {0824-7935}, year = {2004}, abstract = {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}, language = {en} } @article{DelgrandeSchaubTompitsetal.2002, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans and Wang, Kewen}, title = {Towards a classification of preference handling approaches in nonmonotonic reasoning}, isbn = {1-577-35166-5}, year = {2002}, language = {en} } @article{DelgrandeSchaubTompitsetal.2004, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans and Woltran, Stefan}, title = {On Computing belief change operations using quantifield boolean formulas}, issn = {0955-792X}, year = {2004}, abstract = {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}, language = {en} } @article{DelgrandeSchaubTompitsetal.2001, author = {Delgrande, James Patrick and Schaub, Torsten H. and Tompits, Hans and Woltran, Stefan}, title = {On computing solutions to belief change scenarios}, isbn = {3-540- 42464-4}, year = {2001}, language = {en} } @article{DelgrandeSchaubTompitsetal.2013, author = {Delgrande, James and Schaub, Torsten H. and Tompits, Hans and Woltran, Stefan}, title = {A model-theoretic approach to belief change in answer set programming}, series = {ACM transactions on computational logic}, volume = {14}, journal = {ACM transactions on computational logic}, number = {2}, publisher = {Association for Computing Machinery}, address = {New York}, issn = {1529-3785}, doi = {10.1145/2480759.2480766}, pages = {46}, year = {2013}, abstract = {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.}, language = {en} } @article{DimopoulosGebserLuehneetal.2019, author = {Dimopoulos, Yannis and Gebser, Martin and L{\"u}hne, Patrick and Romero Davila, Javier and Schaub, Torsten H.}, title = {plasp 3}, series = {Theory and practice of logic programming}, volume = {19}, journal = {Theory and practice of logic programming}, number = {3}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068418000583}, pages = {477 -- 504}, year = {2019}, abstract = {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.}, language = {en} } @article{DurzinskyMarwanOstrowskietal.2011, author = {Durzinsky, Markus and Marwan, Wolfgang and Ostrowski, Max and Schaub, Torsten H. and Wagler, Annegret}, title = {Automatic network reconstruction using ASP}, series = {Theory and practice of logic programming}, volume = {11}, journal = {Theory and practice of logic programming}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068411000287}, pages = {749 -- 766}, year = {2011}, abstract = {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.}, language = {en} } @article{FandinnoLifschitzLuehneetal.2020, author = {Fandinno, Jorge and Lifschitz, Vladimir and L{\"u}hne, Patrick and Schaub, Torsten H.}, title = {Verifying tight logic programs with Anthem and Vampire}, series = {Theory and practice of logic programming}, volume = {20}, journal = {Theory and practice of logic programming}, number = {5}, publisher = {Cambridge Univ. Press}, address = {Cambridge [u.a.]}, issn = {1471-0684}, doi = {10.1017/S1471068420000344}, pages = {735 -- 750}, year = {2020}, abstract = {This paper continues the line of research aimed at investigating the relationship between logic programs and first-order theories. We extend the definition of program completion to programs with input and output in a subset of the input language of the ASP grounder gringo, study the relationship between stable models and completion in this context, and describe preliminary experiments with the use of two software tools, anthem and vampire, for verifying the correctness of programs with input and output. Proofs of theorems are based on a lemma that relates the semantics of programs studied in this paper to stable models of first-order formulas.}, language = {en} } @article{FloeterNicolasSchaubetal.2004, author = {Fl{\"o}ter, Andr{\´e} and Nicolas, Jacques and Schaub, Torsten H. and Selbig, Joachim}, title = {Threshold extraction in metabolite concentration data}, year = {2004}, abstract = {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}, language = {en} } @article{FloeterNicolasSchaubetal.2003, author = {Fl{\"o}ter, Andr{\´e} and Nicolas, Jacques and Schaub, Torsten H. and Selbig, Joachim}, title = {Threshold extraction in metabolite concentration data}, year = {2003}, language = {en} } @article{FloeterSelbigSchaub2004, author = {Fl{\"o}ter, Andr{\´e} and Selbig, Joachim and Schaub, Torsten H.}, title = {Finding metabolic pathways in decision forests}, isbn = {3-540-23221-4}, year = {2004}, language = {en} } @article{FriouxSchaubSchellhornetal.2019, author = {Frioux, Cl{\´e}mence and Schaub, Torsten H. and Schellhorn, Sebastian and Siegel, Anne and Wanko, Philipp}, title = {Hybrid metabolic network completion}, series = {Theory and practice of logic programming}, volume = {19}, journal = {Theory and practice of logic programming}, number = {1}, publisher = {Cambridge University Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068418000455}, pages = {83 -- 108}, year = {2019}, abstract = {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.}, language = {en} } @article{GebserGharibMerceretal.2009, author = {Gebser, Martin and Gharib, Mona and Mercer, Robert E. and Schaub, Torsten H.}, title = {Monotonic answer set programming}, issn = {0955-792X}, doi = {10.1093/logcom/exn040}, year = {2009}, abstract = {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.}, language = {en} } @article{GebserGharibSchaub2007, author = {Gebser, Martin and Gharib, Mona and Schaub, Torsten H.}, title = {Incremental answer sets and their computation}, year = {2007}, language = {en} } @article{GebserKaminskiKaufmannetal.2018, author = {Gebser, Martin and Kaminski, Roland and Kaufmann, Benjamin and L{\"u}hne, Patrick and Obermeier, Philipp and Ostrowski, Max and Romero Davila, Javier and Schaub, Torsten H. and Schellhorn, Sebastian and Wanko, Philipp}, title = {The Potsdam Answer Set Solving Collection 5.0}, series = {K{\"u}nstliche Intelligenz}, volume = {32}, journal = {K{\"u}nstliche Intelligenz}, number = {2-3}, publisher = {Springer}, address = {Heidelberg}, issn = {0933-1875}, doi = {10.1007/s13218-018-0528-x}, pages = {181 -- 182}, year = {2018}, abstract = {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.}, language = {en} } @article{GebserKaminskiSchaub2011, author = {Gebser, Martin and Kaminski, Roland and Schaub, Torsten H.}, title = {Complex optimization in answer set programming}, series = {Theory and practice of logic programming}, volume = {11}, journal = {Theory and practice of logic programming}, number = {3}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068411000329}, pages = {821 -- 839}, year = {2011}, abstract = {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.}, language = {en} } @article{GebserKaufmannKaminskietal.2011, author = {Gebser, Martin and Kaufmann, Benjamin and Kaminski, Roland and Ostrowski, Max and Schaub, Torsten H. and Schneider, Marius}, title = {Potassco the Potsdam answer set solving collection}, series = {AI communications : AICOM ; the European journal on artificial intelligence}, volume = {24}, journal = {AI communications : AICOM ; the European journal on artificial intelligence}, number = {2}, publisher = {IOS Press}, address = {Amsterdam}, issn = {0921-7126}, doi = {10.3233/AIC-2011-0491}, pages = {107 -- 124}, year = {2011}, abstract = {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.}, language = {en} } @article{GebserKaufmannNeumannetal.2007, author = {Gebser, Martin and Kaufmann, Benjamin and Neumann, Andr{\´e} and Schaub, Torsten H.}, title = {Conflict-driven answer set enumeration}, isbn = {978-3-540- 72199-4}, year = {2007}, language = {en} } @article{GebserKaufmannNeumannetal.2007, author = {Gebser, Martin and Kaufmann, Benjamin and Neumann, Andr{\´e} and Schaub, Torsten H.}, title = {Conflict-driven answer set solving}, isbn = {978-1-57735-323-2}, year = {2007}, language = {en} } @article{GebserKaufmannNeumannetal.2007, author = {Gebser, Martin and Kaufmann, Benjamin and Neumann, Andr{\´e} and Schaub, Torsten H.}, title = {Clasp : a conflict-driven answer set solver}, isbn = {978-3-540- 72199-4}, year = {2007}, language = {en} } @article{GebserKaufmannSchaub2012, author = {Gebser, Martin and Kaufmann, Benjamin and Schaub, Torsten H.}, title = {Conflict-driven answer set solving: From theory to practice}, series = {Artificial intelligence}, volume = {187}, journal = {Artificial intelligence}, number = {8}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0004-3702}, doi = {10.1016/j.artint.2012.04.001}, pages = {52 -- 89}, year = {2012}, abstract = {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.}, language = {en} } @article{GebserKaufmannSchaub2012, author = {Gebser, Martin and Kaufmann, Benjamin and Schaub, Torsten H.}, title = {Multi-threaded ASP solving with clasp}, series = {Theory and practice of logic programming}, volume = {12}, journal = {Theory and practice of logic programming}, number = {8}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068412000166}, pages = {525 -- 545}, year = {2012}, abstract = {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.}, language = {en} } @article{GebserLiuNamasivayametal.2007, author = {Gebser, Martin and Liu, Lengning and Namasivayam, Gayathri and Neumann, Andr{\´e} and Schaub, Torsten H. and Truszczynski, Miroslaw}, title = {The first answer set programming system competition}, isbn = {978-3-540- 72199-4}, year = {2007}, language = {en} } @article{GebserObermeierSchaubetal.2018, author = {Gebser, Martin and Obermeier, Philipp and Schaub, Torsten H. and Ratsch-Heitmann, Michel and Runge, Mario}, title = {Routing driverless transport vehicles in car assembly with answer set programming}, series = {Theory and practice of logic programming}, volume = {18}, journal = {Theory and practice of logic programming}, number = {3-4}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {1471-0684}, doi = {10.1017/S1471068418000182}, pages = {520 -- 534}, year = {2018}, abstract = {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.}, language = {en} } @article{GebserSabuncuSchaub2011, author = {Gebser, Martin and Sabuncu, Orkunt and Schaub, Torsten H.}, title = {An incremental answer set programming based system for finite model computation}, series = {AI communications : AICOM ; the European journal on artificial intelligence}, volume = {24}, journal = {AI communications : AICOM ; the European journal on artificial intelligence}, number = {2}, publisher = {IOS Press}, address = {Amsterdam}, issn = {0921-7126}, doi = {10.3233/AIC-2011-0496}, pages = {195 -- 212}, year = {2011}, abstract = {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.}, language = {en} } @article{GebserSchaub2007, author = {Gebser, Martin and Schaub, Torsten H.}, title = {Generic tableaux for answer set programming}, year = {2007}, language = {en} } @article{GebserSchaub2013, author = {Gebser, Martin and Schaub, Torsten H.}, title = {Tableau calculi for logic programs under answer set semantics}, series = {ACM transactions on computational logic}, volume = {14}, journal = {ACM transactions on computational logic}, number = {2}, publisher = {Association for Computing Machinery}, address = {New York}, issn = {1529-3785}, doi = {10.1145/2480759.2480767}, pages = {40}, year = {2013}, abstract = {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.}, language = {en} }