A class of information logics with a decidable validity problem

For a class of propositional information logics defined from Pawlak's information systems, the validity problem is proved to be decidable using a significant variant of the standard filtration technique. Actually the decidability is proved by showing that each logic has the strong finite model property and by bounding the size of the models. The logics in the scope of this paper are characterized by classes of Kripke-style structures with interdependent equivalence relations and closed by the so-called restriction operation. They include Gargov's data analysis logic with local agreement and Nakamura's logic of graded modalities.