A logic simulator can prove the correctness of a digital circuit when it can be shown that only circuits implementing the system specification will produce a particular response to a sequence of simulation commands. By simulating a circuit symbolically, verification can avoid the combinatorial explosion that would normally occur when evaluating circuit operation over many combinations of input and initial state. In this paper, we describe our methodology for verifying synchronous circuits using the stack circuit of Mead and Conway as an illustrative example.