Safety Property Verification of Cyclic Synchronous Circuits

Paper in proceeding, 2003

Today's most common formal verification tools for hardware are unable to deal with circuits containing combinational loops. However, in the areas of hardware compilation, circuit synthesis and circuit optimization, it is quite natural for a subclass of these loops, the so-called constructive loops, to arise. These are loops that physically exist in a circuit, but are never logically taken. In this paper, we present a method for safety property verification of circuits containing constructive combinational loops, based on propositional theorem proving and temporal induction. It can be used to just prove constructivess of circuits, but also to directly prove safety properties of the circuits. Unlike previously proposed methods, no fixed point iteration is needed, we do not have to compute reachable states, and no cycle-free representation of the circuit has to be computed.