On the axiomatization of finite K-frames (Q761445)

The authors find a way to construct a formula which axiomatizes a given finite frame of the modal logic K, i.e., for each finite frame \({\mathcal A}\), they construct a formula which holds in those and only those frames in which every formula true in \({\mathcal A}\) holds. To obtain this result they find, for each finite model \({\mathfrak A}\) and each natural number n, a formula which holds in those and only those models in which every formula true in \({\mathfrak A}\), and involving the first n propositional letters, holds.