A Theory of HR* Graph Conditions and their Application to Meta-Modeling
Hendrik Radke · Carl von Ossiezky University of Oldenburg · 2016
Graph transformation systems are an established visual modeling approach, using graphs to give an intuitive overview of a system. Structural system properties can be expressed by nested conditions (Habel, Pennemann 2009). However, nested conditions can not express non-local properties, like arbitrary-length paths, connectedness or circle-freeness. We propose HR* conditions, extending nested conditions with hyperedge replacement. The expressiveness of several variants HRs conditions is discussed. A method is presented to check the correctness of a specification consisting of a graph program with HR* pre- and postcondition, by utilizing basic transformations on the conditions. HR* conditions are used to generate instances of UML meta-models with OCL constraints. The type graph is transformed into a graph grammar. OCL constraints are transformed into HR* conditions, wich are then integrated into the graph grammar as application conditions to ensure the generation of valid instances.