Abstract

In modal logics we are interested in classes of frames that characterize the logic under consideration. Such classes are usually distinguished by their respective frame properties. In general these characterizations are not unique and it is desirable to find a strongest possible. In this article an approach is presented which helps in this respect. It allows us to transform a given background theory into one which is more general and which modal logics cannot distinguish from the former because of their syntactic and semantic restrictions. The underlying technique is based on the idea to find conservative extensions of a given logic whose frame properties allow us to extract significantly stronger characterizations of the original logic