Representation of constraints in an extended transition network

We inspect the issues of using extended transition networks as a representation for systems development activity as outlined at the first EDRG workshop. In particular, joint work between the two teams authoring this paper is illustrated. The work on the extensions to the transition network as required for systems development (both theoretical and practical aspects) has progressed jointly with work on the further development of GEDBLOG; the deductive DBMS with graphical user interface developed at lEI-CNR. Many aspects of systems development methods have been discussed; this paper concentrates on the representation of different kinds of constraints, as well as on the definition of basic elements of semantics.