Capturing Multi-level Models in a Two-Level Formal Modeling Technique

Conceptual models are often built with techniques that propose a strict stratification of entities into two classification levels: a level of types (or classes) and a level of instances. Multi-level conceptual modeling extends the conventional two-level scheme by admitting that types can be instances of other types, giving rise to multiple levels of classification. Nevertheless, the vast majority of tools and techniques are still confined to the two-level scheme, and hence cannot be used for multi-level models directly. We show here how a multi-level model in ML2 can be transformed into a two-level specification in the formal modeling technique Alloy, thereby leveraging the Alloy analyzer to multi-level models.