Answer Set programming (ASP) is a powerful form of declarative programming used in areas such as planning or reasoning. ASP solvers enforce stable model semantics, which rule out solutions representing certain kinds o...
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Answer Set programming (ASP) is a powerful form of declarative programming used in areas such as planning or reasoning. ASP solvers enforce stable model semantics, which rule out solutions representing certain kinds of circular reasoning. Unfortunately, current ASP solvers are incapable of solving problems involving cyclic dependencies between multiple integer or continuous quantities effectively. In this paper, we generalize the notion of stable models to bound founded variables with arbitrary domains, where bounds on such variables need to be justified by some rule in the program in order for the model to be stable. We show how to handle significantly more general rule forms where bound founded variables can act as head or body variables, and where head and body variables can be related via complex constraints subject to certain monotonicity requirements. We describe a new unfounded set detection algorithm which allows us to enforce this generalization of the stable model semantics. We also show how these unfounded sets can be explained in order to allow effective conflict-directed clause learning. The new solver merges the best features of CP, SAT and ASP solvers and allows new types of problems to be solved very efficiently.
For some computational problems (e. g., product configuration, planning, diagnosis, query answering, phylogeny reconstruction), computing a set of similar/diverse solutions may be desirable for better decision-making....
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For some computational problems (e. g., product configuration, planning, diagnosis, query answering, phylogeny reconstruction), computing a set of similar/diverse solutions may be desirable for better decision-making. With this motivation, we have studied several decision/optimization versions of this problem in the context of Answer set programming (ASP), analyzed their computational complexity, and introduced offline/online methods to compute similar/diverse solutions of such computational problems with respect to a given distance function. All these methods rely on the idea of computing solutions to a problem by means of finding the answer sets for an ASP program that describes the problem. The offline methods compute all solutions of a problem in advance using the ASP formulation of the problem with an existing ASP solver, like clasp, and then identify similar/diverse solutions using some clustering methods (possibly in ASP as well). The online methods compute similar/diverse solutions of a problem following one of the three approaches: by reformulating the ASP representation of the problem to compute similar/diverse solutions at once using an existing ASP solver;by computing similar/diverse solutions iteratively (one after the other) using an existing ASP solver;by modifying the search algorithm of an ASP solver to compute similar/diverse solutions incrementally. All these methods are sound;the offline method and the first online method are complete whereas the others are not. We have modified clasp to implement the last online method and called it clasp-nk. In the first two online methods, the given distance function is represented in ASP;in the last one, however, it is implemented in C++. We have shown the applicability and the effectiveness of these methods using clasp or clasp-nk on two sorts of problems with different distance measures: on a real-world problem in phylogenetics (i.e., reconstruction of similar/diverse phylogenies for Indo-European languages
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...
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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.
The proceedings contain 17 papers. The topics discussed include: probabilistic soft logic: a scalable approach for Markov random fields over continuous-valued variables;rapid text-based authoring of defeasible higher-...
ISBN:
(纸本)9783642396168
The proceedings contain 17 papers. The topics discussed include: probabilistic soft logic: a scalable approach for Markov random fields over continuous-valued variables;rapid text-based authoring of defeasible higher-order logic formulas, via textual logic and rulelog;ontology repositories make a world of difference;formalization of natural language regulations through SBVR structured English;multi-agent activity modeling with the BRAHMS environment;rules and policy based handling of XML in government contexts including NIEM;reasoning over 2D and 3D directional relations in OWL: a rule-based approach;grailog 1.0: graph-logic visualization of ontologies and rules;modeling stable matching problems with answer set programming;a fuzzy, utility-based approach for proactive policy-based management;and picking up the best goal: an analytical study in defeasible logic.
This proceedings contains 6 papers. The conference covers the topics that related to theoretical aspects of computer science, including algorithms and data structures;algorithmic game theory;combinatorial optimization...
ISBN:
(纸本)9781921770265
This proceedings contains 6 papers. The conference covers the topics that related to theoretical aspects of computer science, including algorithms and data structures;algorithmic game theory;combinatorial optimization;computability;computational complexity theory;computational geometry;graph theory and combinatorics;parallel and distributed algorithms;logic and type systems;program derivation, analysis, and verification;theory of programming languages. The key terms of this proceedings include geometric extent problems, multiple-machine power management, weighted flow time, rotated library sort, superstring, logic circuits, beaver machines, range-aggregate query, counting complexity, potential analysis.
In this paper, we present SeaLion, an integrated development environment (IDE) for answer-set programming (ASP). SeaLion provides source-code editors for the languages of Gringo and DLV and offers popular amenities li...
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In this paper, we present SeaLion, an integrated development environment (IDE) for answer-set programming (ASP). SeaLion provides source-code editors for the languages of Gringo and DLV and offers popular amenities like syntax highlighting, syntax checking, code completion, visual program outline, and refactoring functionality. The tool has been realised in the context of a research project whose goal is the development of techniques to support the practical coding process of answer-set programs. In this respect, SeaLion is the first IDE for ASP that provides debugging features that work for real-world answer-set programs and supports the rich languages of modern answer-set solvers. Indeed, SeaLion implements a stepping-based debugging approach that allows the developer to quickly track down programming errors by simply following his or her intuitions on the intended semantics. Besides that, SeaLion supports ASP development using model-driven engineering techniques including domain modelling with extended UML class diagrams and visualisation of answer sets in corresponding instance diagrams. Moreover, customised visualisation as well as visual editing of answer sets is realised by the Kara plugin of SeaLion. Further implemented features are a documentation generator based on the LANA annotation language, support for external solvers, and interoperability with external tools. SeaLion comes as a plugin of the popular Eclipse platform and provides interfaces for future extensions of the IDE.
We describe how the Davis-Putnam-Logemann-Loveland procedure DPLL is bisimilar to the goal-directed proof-search mechanism described by a standard but carefully chosen sequent calculus. We thus relate a procedure desc...
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The proceedings contain 20 papers. The topics discussed include: logic and agent programming languages;natural models of homotopy type theory;modeling infinite structures with atoms;counting in SPARQL property paths: ...
ISBN:
(纸本)9783642399916
The proceedings contain 20 papers. The topics discussed include: logic and agent programming languages;natural models of homotopy type theory;modeling infinite structures with atoms;counting in SPARQL property paths: perspectives from theory and practice;quantitative approaches to information protection;perspectives of dynamic complexity;linear time proof verification on N-graphs: a graph theoretic approach;first order extensions of residue classes and uniform circuit complexity;quantum probabilistic dyadic second-order logic;structural extensions of display calculi: a general recipe;the same, similar, or just completely different? equivalence for argumentation in light of logic;Boolean dependence logic and partially-ordered connectives;extended modal dependence logic EMDL;dependence logic with generalized quantifiers: axiomatizations;continuous truth ii: reflections;and a simple separation logic.
The proceedings contain 32 papers. The topics discussed include: the compiler forest;pretty-big-step semantics;language constructs for non-well-founded computation;laziness by need;compositional invariant checking for...
ISBN:
(纸本)9783642370359
The proceedings contain 32 papers. The topics discussed include: the compiler forest;pretty-big-step semantics;language constructs for non-well-founded computation;laziness by need;compositional invariant checking for overlaid and nested linked lists;a discipline for program verification based on backpointers and its use in observational disjointness;modular reasoning about separation of concurrent data structures;ribbon proofs for separation logic;abstract refinement types;constraining delimited control with contracts;verifying concurrent memory reclamation algorithms with grace;verifying concurrent programs against sequential specifications;behavioral polymorphism and parametricity in session-based communication;higher-order processes, functions, and sessions: a monadic integration;and structural lock correlation with ownership types.
We present an approach for handling non-local control flow (goto and return statements) in the presence of allocation and deallocation of block scope variables in imperative programming languages. We define a small st...
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ISBN:
(纸本)9783642370755;9783642370748
We present an approach for handling non-local control flow (goto and return statements) in the presence of allocation and deallocation of block scope variables in imperative programming languages. We define a small step operational semantics and an axiomatic semantics (in the form of a separation logic) for a small C-like language that combines these two features, and which also supports pointers to block scope variables. Our operational semantics represents the program state through a generalization of Huet's zipper data structure. We prove soundness of our axiomatic semantics with respect to our operational semantics. This proof has been fully formalized in Coq.
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