A lazy approach to symmetry reduction

Thomas Wahl (1) , Vijay d'Silva (1)

1 Computing Science Laboratory - Oxford University

is a technique to counter state explosion for systems with regular structure. It relies on idealistic assumptions about indistinguishable components, which in practice may only be similar. In this article, we present a flexible, lazy approach to symmetry-reducing a structure without any prior knowledge about its global symmetry. Instead of a-priori checking for compliance with symmetry conditions, each encountered state is annotated on the fly with information about how symmetry is along the path leading to it. The method naturally favors “very symmetric” systems: more similarity among the components leads to greater compression. A notion of is used to prune the annotated search space during exploration. Previous solutions to the approximate symmetry reduction problem are restricted to specific types of asymmetry, such as up to bisimilarity, or incur a large overhead, either during preprocessing of the structure or during the verification run. In contrast, the strength of our method is its balance between ease of implementation and algorithmic flexibility. We include analytic and experimental results that witness its efficiency.

Mots clés: Model checking; Symmetry; Annotated Structure; Partition; Subsumption

Thomas Wahl, Vijay d'Silva. A lazy approach to symmetry reduction. Formal Aspects of Computing, 2009, 22 (6), pp.713-733. ⟨10.1007/s00165-009-0131-x⟩. ⟨hal-00536833⟩