Extending equivalence class computation to large FSMs

Abstract

Computing equivalence classes for finite state machines (FSMs) has several applications to synthesis and verification problems, like state minimization, automata reduction, and logic optimization with don't cares. Symbolic traversal techniques are applicable to medium-small circuits. This paper extends their use to large FSMs by means of cofactor-based enhancements to the state-of-the-art approaches and of underestimations of equivalence classes. The key to success is pruning the search space by constraining it. Experimental results on some of the larger ISCAS'89 and MCNC circuits show its applicability.