A Model for Representing Programs Using Hierarchical Graphs

In this paper a hierarchical graph model for programs based on the concepts of recursive graphs (RG's) and Codd relations is presented. The purpose of the model is to clearly represent the structure of a program implemented in a structured language, such as Pascal, Algol, or PL/1, so that the program can be analyzed and modifications to the program can be clearly specified. The model uses an RG representation for the control flow and the data flow with an equivalent relational representation. It also has a relational representation for the objects defmed within the program. The various aspects of the model are illustrated using Pascal constructs and a model for an example Pascal program is given.