Deriving Unbounded Reachability Proof of Linear Hybrid Automata during Bounded Checking Procedure

Abstract

Reachability analysis of linear hybrid automata (LHA) is an important problem. Classical model checking (CMC) technique is not scalable and not guaranteed to terminate. On the other hand, bounded model checking (BMC) is more cost-effective to conduct but can not guarantee the safety beyond the bound. In this paper, we seek to bridge the gap between BMC and CMC for reachability analysis of LHA. During BMC of LHA, typical procedures can discover sets of unsatisfiable constraint cores, which can be mapped back to path segments in the graph structure of LHA. If every path connecting the initial and target location has to go through such infeasible path segment, the target location is entirely not reachable. Based on this characteristic, we propose a LTL model checking based approach to check whether the target location is blocked. To further optimize the performance, we propose an automata based solution to check the LTL specification incrementally and adopt an on-the-fly algorithm to check the accepting condition to avoid an explicit construction of product automata.