Exploiting Transition Locality in Automatic Verification

Abstract

Abstract. In this paper we present an algorithm to contrast state explosion when using Explicit State Space Exploration to verify protocols. We show experimentally that protocols exhibit transition locality. We present a verification algorithm that exploits transition locality as well as an implementation of it within the Murϕ verifier. Our algorithm is compatible with all Breadth First (BF) optimization techniques present in the Murϕ verifier and it is by no means a substitute for any of them. In fact, since our algorithm trades space with time, it is typically most useful when one runs out of memory and has already used all other state reduction techniques present in the Murϕ verifier. Our experimental results show that using our approach we can typically save more than 40% of RAM with an average time penalty of about 50% when using (Murϕ) bit compression and 100% when using bit compression and hash compaction.

Integrating RAM and Disk Based Verification within the Murϕ Verifier

“…This was done as illustrated, respectively, in [9] and [2]. The resulting verifiers are called, respectively, Cached-Murϕ and Disk-Murϕ.…”

“…Our goal is to devise a serialization scheme for the RAM based state exploration algorithm presented in [9] (CBF, for Cached Breadth First visit in the following) and the disk based state exploration algorithm presented in [2] (DBF, for Disk Breadth First visit in the following). Figure 1 shows the algorithm and data structures used by a Breadth First (BF) visit.…”

“…Algorithm CBF [9] implements BF queue Q on disk and, most importantly, replaces with a cache table the hash table T used by the standard BF visit in Figure 1. Using a cache table rather than a hash table means that, upon a collision, CBF may forget visited states and, as a result, it may revisit states.…”

“…In this section we present a serialization scheme for the RAM based state space exploration algorithm CBF [9] and the disk based state space exploration algorithm DBF [2].…”

“…-We present (Section 3) an integration scheme (we call it serialization scheme) for the RAM based verification algorithm presented in [9] and the disk based verification algorithm presented in [2]. -We present (Section 4) experimental results on using our serialization scheme implemented within the Murϕ verifier.…”