An Abstract Equivalence Notion for Object Models

Equivalence notions for object models are usually too concrete in the sense that they assume that the compared models are formed by elements with the same names. This is not adequate in several situations: during model refactoring, when using auxiliary model elements, or when the compared models comprise distinct but corresponding elements. So, in this paper, we propose a more abstract and language-independent equivalence notion for object models. It supports, as desired, abstraction from names and elements when comparing models. We use the PVS system to specify and prove properties of our notion. It is illustrated here by comparing simple models in Alloy, a formal object-oriented modeling language, but has also been applied for deriving a comprehensive set of algebraic laws for Alloy.