Abstract

The results were presented at the Seminar of Department of Logic ofJagiellonian University.An intermediate logic L has the Interpolation Property i for every ! 2 L, if V ar() \ V ar() =6 ;, then there exists a formula builtup from variables occurring both in and in such that ! 2 L, ! 2 L denotes the set of all variables occurring in ).The following simple lemma will be used in the sequel:Lemma. If a formula is built up from the variable x only, then ! 2 INT or ::x ! 2 INT.The proof reduces to the easy observation of the Rieger-Nishimura al-gebra