Abstract. Algebraic graph transformation is a well known rule-based approach to manipulate graphs that can be applied in many contexts. In this paper we use it in the context of model-driven engineering (MDE). Graph transformation rules usually only describing changes of one graph, however there are use cases such as model co-evolution where not only a single graphshouldbemanipulatedbutrelatedones.Theco-transformation of type graphs together with their instance graphs has shown to be a promising approach to formalize model and meta-model co-evolution. In this paper, we extend our earlier work on co-evolution by allowing transformation rules that have less restrictions so that graph manipulations such as merging and retyping of graph elements become possible.
