An efficient algorithm to search for minimal closed covers in sequential machines

The removal of redundant states in a finite state machine (FSM) is essential to reducing the complexity of a sequential circuit. An efficient algorithm for state minimization in incompletely specified state machines is presented. This algorithm employs a tight lower bound and a fail-first heuristic and generates a relatively small search space from the prime compatibles. It utilizes efficient pruning rules to further reduce the search space and finds a minimal closed cover. The technique guarantees the elimination of all the redundant states in a very short execution time. Experimental results with a large number of FSMs including the MCNC FSM benchmarks are presented. The results are compared with other work in this area