Van Kampen Squares For Graph Transformation

This paper demonstrates the benefits of a recent result by the authors, proving a necessary and sufficient condition for a pushout of two morphisms to be a Van Kampen Square, even if both morphisms are not monomorphisms. The theorem can be applied in categories that are based on graph structure signatures. We discuss its value in the context of general views on co-transformations and illustrate an application in a software co-evolution scenario.