The Complexity of One-Agent Refinement Modal Logic.

We investigate the complexity of satisfiability for one-agent refinement modal logic (RML), an extension of basic modal logic (ML) obtained by adding refinement quantifiers on structures. RML is known to have the same expressiveness as ML, but the translation of RML into ML is of non-elementary complexity, and RML is at least doubly exponentially more succinct than ML. In this paper we show that RML-satisfiability is ‘only’ singly exponentially harder than ML-satisfiability, the latter being a well-known PSPACE-complete problem.