Symmetry-breaking Answer Set Solving

TL;DR

This paper introduces a method for symmetry-breaking in Answer Set Programming by reducing logic programs to coloured digraphs, enabling the use of graph automorphisms to simplify the search space.

Contribution

It proposes a novel reduction of disjunctive logic programs to coloured digraphs and integrates a preprocessor with a graph automorphism system for symmetry-breaking.

Findings

Significant reduction in search space complexity

Effective elimination of symmetric solutions

Improved computational performance in experiments

Abstract

In the context of Answer Set Programming, this paper investigates symmetry-breaking to eliminate symmetric parts of the search space and, thereby, simplify the solution process. We propose a reduction of disjunctive logic programs to a coloured digraph such that permutational symmetries can be constructed from graph automorphisms. Symmetries are then broken by introducing symmetry-breaking constraints. For this purpose, we formulate a preprocessor that integrates a graph automorphism system. Experiments demonstrate its computational impact.