Proving the equivalenceof two Finite State Machines (FSMs) has many applications to synthesis, verication, testing, and diagnosis. Building their product machine is a theoretical framework for equivalence proof. There are some cases where product machine traversal, a necessary and sucient check, is mandatory. This is muchmore complexthan traversingjust one of the componentmachines. This paperproposes an equivalence-preservingfunctionthat transformsthe productmachinein the General Product Machine (GPM). Using the GPM in symbolicstate space traversal reduces the size of the BDDs and makes image computation easier. As a result, GPM traversal is much less expensive than product machine traversal, its cost being close to dealing with a single machine.