Labelled Port Graph – A Formal Structure for Models and Computations

We present a general definition of labelled port graph that serves as a basis for the design of graph-based programming and modelling frameworks (syntax and semantics). We show that this structure provides the syntax for programs, which are composed of an initial graph, a set of rules and a strategy. Rules, represented as labelled port graphs, apply to states, also represented as labelled port graphs, and compute their successors according to the given strategy. The description of states, rules, and computations controlled by strategies, using labelled port graphs, is detailed and illustrated with examples from Porgy, a strategic port graph rewriting environment for the design of executable specifications of complex systems.