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Rewriting recursive aggregates in answer set programming: back to monotonicity

Alviano, Mario, Faber, Wolfgang and Gebser, Martin (2015) Rewriting recursive aggregates in answer set programming: back to monotonicity. Theory and Practice of Logic Programming, 15 (4-5). pp. 559-573. ISSN 1471-0684

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Aggregation functions are widely used in answer set programming for representing and reasoning on knowledge involving sets of objects collectively. Current implementations simplify the structure of programs in order to optimize the overall performance. In particular, aggregates are rewritten into simpler forms known as monotone aggregates. Since the evaluation of normal programs with monotone aggregates is in general on a lower complexity level than the evaluation of normal programs with arbitrary aggregates, any faithful translation function must introduce disjunction in rule heads in some cases. However, no function of this kind is known. The paper closes this gap by introducing a polynomial, faithful, and modular translation for rewriting common aggregation functions into the simpler form accepted by current solvers. A prototype system allows for experimenting with arbitrary recursive aggregates, which are also supported in the recent version 4.5 of the grounder gringo, using the methods presented in this paper.

Item Type: Article
Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Q Science > QA Mathematics > QA76 Computer software
Schools: School of Computing and Engineering
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Depositing User: Wolfgang Faber
Date Deposited: 10 Feb 2016 15:19
Last Modified: 10 Feb 2016 19:30


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