Term Graph Rewriting

O. Introduction. In this paper we will discuss in an informM way some aspects of t@rm graph rewriting. We will indicate why this subject falls in the scope of higher-order rewriting, and thus in the scope of the present workshop. Our discussion will be loosely structured by a numbered sequence of keywords and phrases, thereby following a talk given at the workshop. In the theory of rewriting, term graph rewriting is a relatively new development, prompted by the actual practice in functional language implementations where subterm sharing is a mat ter of routine. There are several approaches to a theoretical foundation of graph rewriting, of which an important one is that based on category theory and single or double push-outs. We will not discuss this approach here, but instead refer to [SPvE93] where several references to the categorical t reatment can be found.