参数化系统安全性的启发式符号验证

参数化系统(paramterized system)是指包含特定有限状态进程多个实例的并发系统,其中的参数是指系统内进程实例的数目,即系统的规模.反向可达性分析(backward reachability analysis)已被广泛用于验证参数化系统是否满足以向上封闭(upward-closed)集合表示的安全性(safety property).与有限状态系统验证相类似,参数化系统的验证同样也面临着状态爆炸(state explosion)问题,并且模型检测算法的有效性依赖于如何采用有效的数据结构表示状

Heuristic Symbolic Verification of Safety Properties for Parameterized Systems

A parameterized system is a system that involves numerous instantiations of the same finite-state process, and depends on a parameter which defines its size. The backward reachability analysis has been widely used for verifying parameterized systems against safety properties modeled as a set of upward-closed sets. As in the finite-state case, the verification of parameterized systems also faces the state explosion problem and the success of model checking depends on the data structure used for representing a set of states. Several constraint-based approaches have been proposed to symbolically represent upward-closed sets with infinite states. But those approaches are still facing the symbolic state explosion problem or the containment problem, i.e. to decide whether a set of concrete states represented by one set of constraints is a subset of another set of constraints, which is co-NP complete. As a result, those examples investigated in the literature would be considered of negligible size in finite-state model checking. This paper presents several heuristic rules specific to parameterized systems that can help to mitigate the problem. Experimental results show that the efficiency is significantly improved and the heuristic algorithm is several orders of magnitude faster than the original one in certain cases.