Constraint Answer Set Programming without Grounding

Extending ASP with constraints (CASP) enhances its expressiveness and performance. This extension is not straightforward as the grounding phase, present in most ASP systems, removes variables and the links among them, and also causes a combinatorial explosion in the size of the program. Several meth...

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Bibliographic Details
Published in:Theory and practice of logic programming Vol. 18; no. 3-4; pp. 337 - 354
Main Authors: ARIAS, JOAQUIN, CARRO, MANUEL, SALAZAR, ELMER, MARPLE, KYLE, GUPTA, GOPAL
Format: Journal Article
Language:English
Published: Cambridge, UK Cambridge University Press 01.07.2018
Subjects:
Combinatorial analysis
Mathematical models
Mathematical programming
Original Article
ISSN:1471-0684, 1475-3081
Online Access:Get full text
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Summary:Extending ASP with constraints (CASP) enhances its expressiveness and performance. This extension is not straightforward as the grounding phase, present in most ASP systems, removes variables and the links among them, and also causes a combinatorial explosion in the size of the program. Several methods to overcome this issue have been devised: restricting the constraint domains (e.g., discrete instead of dense), or the type (or number) of models that can be returned. In this paper we propose to incorporate constraints into s(ASP), a goal-directed, top-down execution model which implements ASP while retaining logical variables both during execution and in the answer sets. The resulting model, s(CASP), can constrain variables that, as in CLP, are kept during the execution and in the answer sets. s(CASP) inherits and generalizes the execution model of s(ASP) and is parametric w.r.t. the constraint solver. We describe this novel execution model and show through several examples the enhanced expressiveness of s(CASP) w.r.t. ASP, CLP, and other CASP systems. We also report improved performance w.r.t. other very mature, highly optimized ASP systems in some benchmarks.
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ISSN:1471-0684
1475-3081
DOI:10.1017/S1471068418000285