Algorithms for Kleene Algebra with Converse

Brunet Paul (1) , Damien Pous (1)

1 LIP - Laboratoire de l'Informatique du Parallélisme

The equational theory generated by all algebras of binary relations with operations of union, composition, converse and reflexive transitive closure was studied by Bernátsky, Bloom, Ésik and Stefanescu in 1995. In particular, they obtained its decidability by using a particular automata construction. We show that deciding this equational theory is PSPACE-complete, by providing a PSPACE\ algorithm (the problem is easily shown to be PSPACE-hard). We obtain other algorithms that are time-efficient in practice, despite not being PSPACE. Our results use an alternative automata construction, inspired by the one from Bloom, Ésik and Stefanescu. We relate those two constructions by exhibiting a bisimulation between the resulting deterministic automata, and by showing how our construction results in more sharing between states, thus producing smaller automata.

Mots clés: Kleene algebra; converse; automata; decidability; PSPACE; algorithm; bisimulation

Domaines: Logique en informatique [cs.LO]

Brunet Paul, Damien Pous. Algorithms for Kleene Algebra with Converse. [Research Report] LIP - ENS Lyon. 2014. ⟨hal-01073936v1⟩