A Forward-Backward Abstraction Refinement Algorithm

Abstraction refinement-based model checking has become a standard approach for efficiently verifying safety properties of hardware/software systems. Abstraction refinement algorithms can be guided by counterexamples generated from abstract transition systems or by fixpoints computed in abstract domains. Cousot, Ganty and Raskin recently put forward a new fixpoint-guided abstraction refinement algorithm that is based on standard abstract interpretation and improves the state-of-the-art, also for counterexample-driven methods. This work presents a new fixpoint-guided abstraction refinement algorithm that enhances the Cousot-Ganty-Raskin’s procedure. Our algorithm is based on three main ideas: (1) within each abstraction refinement step, we perform multiple forward-backward abstract state space traversals; (2) our abstraction is a disjunctive abstract domain that is used both as an overapproximation and an underapproximation; (3) we maintain and iteratively refine an overapproximation M of the set of states that belong to some minimal (i.e. shortest) counterexample to the given safety property so that each abstract state space traversal is limited to the states inM .