PROGRES, A Visual Language and Environment for PROgramming with Graph
REwrite Systems

A. Schürr

	  Graphs paly an important role within many areas of
	  applied computer science, and there exists an abundance of
	  (diagrammatic) visual languages which have graphs as their
	  underlying data model.  Furthermore, rule-based languages and
	  systems have proven to be well-suited for the description of
	  complex transformation or inference processes on complex data
	  structures. Although graphs and rule-based systems are quite
	  popular, their combination in the form of graph rewriting
	  systems (graph grammars) were more or less unknown among
	  computer scientists for a very long time.

	  Nowadays the situation is gradually improving with the
	  appearance of a number of graph grammar based languages and
	  tools. Currently, the multi-paradigm language PROGRES is the
	  latest and most expressive descendant of a whole family of
	  graph-rewriting system based specification languages. It
	  has the flavor of a visual database programming language
	  with powerful pattern matching and replacing facilities as
	  well as backtracking capabilities. An integrated set of
	  language-specific tools supports editing, analyzing, and
	  debugging of applications, and even prototypes of PROGRES
	  compilers with Modula-2 and C as target languages are available.