Reliable hashing without collision detection

Abstract

Thanks to a variety of new techniques, state-space exploration is becoming an increasingly effective method for the verification of concurrent programs. One of these techniques, hashing without collision detection, was proposed by Holzmann as a way to vastly reduce the amount of memory needed to store the explored state space. Unfortunately, this reduction in memory use comes at the price of a high probability of ignoring part of the state space and hence of missing existing errors. In this paper, we carefully analyze this method and show that, by using a modified strategy, it is possible to reduce the risk of error to a negligible amount while maintaining the memory use advantage of Holzmann’s technique. Our proposed strategy has been implemented and we describe experiments that confirm the excellent expected results.