Finite Satisfiability of UML Class Diagrams with Constrained Class Hierarchy

Models lie at the heart of the emerging model-driven engineering approach. In order to guarantee precise, consistent, and correct models, there is a need for efficient powerful methods for verifying model correctness. Class diagram is the central language within UML. Its correctness problems involve issues of contradiction, namely the consistency problem, and issues of finite instantiation, namely the finite satisfiability problem. This article analyzes the problem of finite satisfiability of class diagrams with class hierarchy constraints and generalization-set constraints. The article introduces the FiniteSat algorithm for efficient detection of finite satisfiability in such class diagrams, and analyzes its limitations in terms of complex hierarchy structures. FiniteSat is strengthened in two directions. First, an algorithm for identification of the cause for a finite satisfiability problem is introduced. Second, a method for propagation of generalization-set constraints in a class diagram is introduced. The propagation method serves as a preprocessing step that improves FiniteSat performance, and helps developers in clarifying intended constraints. These algorithms are implemented in the FiniteSatUSE tool [BGU Modeling Group 2011b], as part of our ongoing effort for constructing a model-level integrated development environment [BGU Modeling Group 2010a].