Correctness of recursive flow diagram programs

Abstract

This paper presents a simple algebraic description of the semantics of non-deterministic recursive flow diagram programs with parallel assignment, culminating in a method for proving their partial correctness which generalizes the well-known Floyd-Naur method for ordinary flow diagram programs. Our treatment involves first considering a program scheme, and then interpreting it in an appropriate semantic model. The program schemes are conveniently viewed as diagrams in an algebraic theory, with semantic model a relational algebra. Some examples are given in a simple programming language whose features correspond precisely to our algebraic framework.