The Impact of Treewidth on ASP Grounding and Solving

Bliem, Bernhard; Moldovan, Marius; Morak, Michael; Woltran, Stefan

doi:10.24963/ijcai.2017/118

Cited by 10 publications

(6 citation statements)

References 20 publications

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“…Furthermore, we want to design a version of SmartDecomposition specifically geared towards solvers, with the aim of further automatically optimizing the whole ASP computational process. A starting point to this direction can be the recent work of Bliem et al (2017), where it emerged that the performance of modern solvers are highly influenced by the tree-width of the input program; thus, this represents a starting point to explore the potential of our technique on the solving step.…”

Section: Resultsmentioning

confidence: 99%

Optimizing Answer Set Computation via Heuristic-Based Decomposition

Calimeri

Perri

Zangari

2019

Theory and Practice of Logic Programming

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Answer Set Programming (ASP) is a purely declarative formalism developed in the field of logic programming and non-monotonic reasoning: computational problems are encoded by logic programs whose answer sets, corresponding to solutions, are computed by an ASP system. Different, semantically equivalent, programs can be defined for the same problem; however, performance of systems evaluating them might significantly vary. We propose an approach for automatically transforming an input logic program into an equivalent one that can be evaluated more efficiently. One can make use of existing tree-decomposition techniques for rewriting selected rules into a set of multiple ones; the idea is to guide and adaptively apply them on the basis of proper new heuristics, to obtain a smart rewriting algorithm to be integrated into an ASP system. The method is rather general: it can be adapted to any system and implement different preference policies. Furthermore, we define a set of new heuristics tailored at optimizing grounding, one of the main phases of the ASP computation; we use them in order to implement the approach into the ASP systemDLV, in particular into its grounding subsystemℐ-DLV, and carry out an extensive experimental activity for assessing the impact of the proposal.

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Section: Resultsmentioning

confidence: 99%

Optimizing Answer Set Computation via Heuristic-Based Decomposition

Calimeri

Perri

Zangari

2019

Theory and Practice of Logic Programming

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“…It would be interesting to investigate if and how parts of ELPs can be replaced in such a way that the solving performance of selp improves, seeing that selp is sensitive to treewidth. This could lead to an encoding technique for ELPs that tries to minimize the treewidth, similar to the class of connection-guarded ASP (Bliem et al . 2017), which was recently proposed in order to write ASP programs in such a way as to keep the treewidth of the resulting ground program low.…”

Section: Discussionmentioning

confidence: 99%

selp: A Single-Shot Epistemic Logic Program Solver

Bichler¹,

Morak²,

Woltran³

2020

Theory and Practice of Logic Programming

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AbstractEpistemic logic programs (ELPs) are an extension of answer set programming (ASP) with epistemic operators that allow for a form of meta-reasoning, that is, reasoning over multiple possible worlds. Existing ELP solving approaches generally rely on making multiple calls to an ASP solver in order to evaluate the ELP. However, in this paper, we show that there also exists a direct translation from ELPs into non-ground ASP with bounded arity. The resulting ASP program can thus be solved in a single shot. We then implement this encoding method, using recently proposed techniques to handle large, non-ground ASP rules, into the prototype ELP solving system “selp,” which we present in this paper. This solver exhibits competitive performance on a set of ELP benchmark instances.

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“…This work is an improved and significantly extended version of the conference publications by Bliem, Moldovan, Morak, and Woltran (2017) and Bliem (2018), and contains additional proofs, constructions, and discussions, based on the PhD thesis of Bliem (2017). It was funded in part by the Austrian Science Fund (FWF) under grant numbers Y698, P30930, and P32830, as well as by the Academy of Finland under grants 276412 and 312662.…”

Section: Acknowledgmentsmentioning

confidence: 99%

The Impact of Treewidth on Grounding and Solving of Answer Set Programs

Bliem

Morak

Moldovan

et al. 2020

jair

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In this paper, we aim to study how the performance of modern answer set programming (ASP) solvers is influenced by the treewidth of the input program and to investigate the consequences of this relationship. We first perform an experimental evaluation that shows that the solving performance is heavily influenced by treewidth, given ground input programs that are otherwise uniform, both in size and construction. This observation leads to an important question for ASP, namely, how to design encodings such that the treewidth of the resulting ground program remains small. To this end, we study two classes of disjunctive programs, namely guarded and connection-guarded programs. In order to investigate these classes, we formalize the grounding process using MSO transductions. Our main results show that both classes guarantee that the treewidth of the program after grounding only depends on the treewidth (and the maximum degree, in case of connection-guarded programs) of the input instance. In terms of parameterized complexity, our findings yield corresponding FPT results for answer-set existence for bounded treewidth (and also degree, for connection-guarded programs) of the input instance. We further show that bounding treewidth alone leads to NP-hardness in the data complexity for connection-guarded programs, which indicates that the two classes are fundamentally different. Finally, we show that for both classes, the data complexity remains as hard as in the general case of ASP.

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The Impact of Treewidth on ASP Grounding and Solving

Cited by 10 publications

References 20 publications

Optimizing Answer Set Computation via Heuristic-Based Decomposition

Optimizing Answer Set Computation via Heuristic-Based Decomposition

selp: A Single-Shot Epistemic Logic Program Solver

The Impact of Treewidth on Grounding and Solving of Answer Set Programs

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