Combining Abstraction Refinement and SAT-Based Model Checking

Unbounded model checking methods based on Boolean satisfiability (SAT) solvers are proving to be a viable alternative to BDD-based model checking. These methods include, for example, interpolation based and sequential ATPG-based approaches. In this paper, we explore the implications of using abstraction refinement in conjunction with interpolation-based model checking. Based on experiments using a large industrial benchmark set, we conclude that when using interpolationbased model checking, measures must be taken to prevent the overhead of abstraction refinement from dominating runtime. We present two new approaches to this problem. One is a hybrid approach that decides heuristically when to apply abstraction. The other is a very coarse but inexpensive abstraction method based on ideas from ATPG. This approach can produce order-of-magnitude reductions in memory usage, allowing significantly larger designs to be verified.