US Patent 7428712 Design optimization using approximate reachability analysis

Aspects of computing design invariants, by using approximate reachability analysis, include reducing the circuit model for verification and synthesis. Further included is computing invariants using approximate reachability analysis to optimize a circuit model by identifying a plurality of next states for a present state, the plurality of next states capable of being reached from the present state in one transition. The plurality of bits of the next states are compared with a plurality of bits of the present state, and each bit of the present state that is different from at least one next state is changed to variant.