Strategic port graph rewriting: an interactive modelling framework

Abstract

Abstract. We present strategic port graph rewriting as a basis for the implementation of visual modelling tools. The goal is to facilitate the specification and programming tasks associated with the modelling of complex systems. A system is represented by an initial graph and a collection of graph rewrite rules, together with a user-defined strategy to control the application of rules. The traditional operators found in strategy languages for term rewriting have been adapted to deal with the more general setting of graph rewriting, and some new constructs have been included in the strategy language to deal with graph traversal and management of rewriting positions in the graph. We give a formal semantics for the language, and describe its implementation: the graph transformation and visualisation tool Porgy.

Finding the Transitive Closure of Functional Dependencies using Strategic Port Graph Rewriting

“…Let R be a relation schema and Σ its set of functional dependencies. A Funtional Dependency Port Graph representing Σ is an attributed port graph [12] G Σ = (V, P, E, D) F and is defined as: • P = P A ∪ P FD is a union of two defined sets of ports:…”

“…For as long as there is at least one FD node the strategy hasn't visited and iterated, do Proof. From the semantics of strategic port graph programs [12] we know that strategy constructs we use (match(), while(), repeat(one()) and one()) will not branch the Derivation Tree at all. The loop constructs we use execute their arguments sequentially as many times as they apply.…”

Implementation of a Port-graph Model for Finance

“…Port graphs are transformed by applying port graph rewrite rules. We refer to [4] for a formal definition of labelled port graphs, where labels are records, i.e., lists of pairs attribute-value. The values can be concrete (numbers, Booleans, etc.)…”

“…Definition 5 (Match) [4] Let L ⇒ R be a port graph rewrite rule and G a port graph. We say a match g(L) of the left-hand side (i.e., a redex) is found if: there is a port graph morphism g from L to G (hence g(L) is a subgraph of G), C holds, and for each port in L that is not connected to the arrow node, its corresponding port in g(L) must not be an extremity in the set of edges of G − g(L).…”

“…Intuitively, the derivation tree is a representation of the possible evolutions of the system starting from a given initial state (each derivation provides a trace, which can be used to analyse and reason about the behaviour of system). In PORGY [4], the strategy language allows us to control the way derivations are generated. The strategy expression setPos(crtGraph) sets the position graph as the full current graph.…”