lpopt: A Rule Optimization Tool for Answer Set Programming

TL;DR

lpopt is a tool that decomposes large ASP rules into smaller, more manageable rules, enhancing solver performance and making ASP programming more accessible without extensive manual tuning.

Contribution

We extend a previous rule decomposition approach to fully support ASP syntax, including aggregates, weak constraints, and arithmetic, with a detailed algorithm and experimental validation.

Findings

Decomposition reduces grounding size and improves solver efficiency.

lpopt effectively handles complex ASP constructs.

Experimental results confirm the approach's viability.

Abstract

State-of-the-art answer set programming (ASP) solvers rely on a program called a grounder to convert non-ground programs containing variables into variable-free, propositional programs. The size of this grounding depends heavily on the size of the non-ground rules, and thus, reducing the size of such rules is a promising approach to improve solving performance. To this end, in this paper we announce lpopt, a tool that decomposes large logic programming rules into smaller rules that are easier to handle for current solvers. The tool is specifically tailored to handle the standard syntax of the ASP language (ASP-Core) and makes it easier for users to write efficient and intuitive ASP programs, which would otherwise often require significant hand-tuning by expert ASP engineers. It is based on an idea proposed by Morak and Woltran (2012) that we extend significantly in order to handle the full ASP syntax, including complex constructs like aggregates, weak constraints, and arithmetic expressions. We present the algorithm, the theoretical foundations on how to treat these constructs, as well as an experimental evaluation showing the viability of our approach.