Automatic proof search in logic of justified common knowledge

We consider the logic of justified common knowledge S4n introduced in [Artemov, 2004]. This system captures the notion of justified common knowledge, which is free of some of the deficiencies of the usual common knowledge operator, and yet sufficient for analysis of epistemic problems where common knowledge has been traditionally applied. In particular, S4n enjoys cut-elimination, which opens a possibility for an automatic proof search in logic of common knowledge. In this paper, we present an implementation that automatically builds cut-free proofs in S4n. Our work is based on the existing matrix-based prover for intuitionistic logic [Schmitt et al., 2001].