Abstract

We present a procedure transforming intuitionistic matrix proofs into proofs within the intuitionistic standard sequent calculus. The transformation is based on L. Wallen’s proof justifying his matrix characterization for the validity of intuitionistic formulae. Since this proof makes use of Fitting‘s non-standard sequent calculus our procedure consists of two steps. First a non-standard sequent proof will be extracted from a given matrix proof. Secondly we transform each non-standard proof into a standard proof in a structure preserving way. To simplify the latter step we introduce an extended standard calculus which is shown to be sound and complete.

Citations