A collection operator for graph transformation

Algebraic graph transformation has a wellestablished theory and associated tools that can be used to perform model transformations. However, the lack of a construct to match and transform collections of similar subgraphs makes graph transformation complex or even impractical to use in a number of transformation cases. This is addressed in this paper, by defining a collection operator which is powerful, yet simple to model and understand. A rule can contain multiple collection operators, each with lower and upper bound cardinalities, and the collection operators can be nested. An associated matching process dynamically builds a collection free rule that enables us to reuse the existing graph transformation apparatus. We present model transformation examples from different modeling domains to illustrate the benefit of the approach.