Encoding OCL Data Types for SAT-Based Verification of UML/OCL Models

Checking the correctness of UML/OCL models is a crucial task in the design of complex software and hardware systems. As a consequence, several approaches have been presented which address this problem. Methods based on satisfiability (SAT) solvers have been shown to be very promising in this domain. Here, the actual verification task is encoded as an equivalent bit-vector instance to be solved by an appropriate solving engine. However, while a bit-vector encoding for basic UML/OCL constructs has already been introduced, no encoding for non-trivial OCL data types and operations is available so far. In this paper, we close this gap and present a bit-vector encoding for more complex OCL data types, i.e. sets, bags, and their ordered counterparts. As a result, SAT-based UML/OCL verification becomes applicable for models containing these collections types. A case study illustrates the application of this encoding.