US Patent 7260799 Exploiting suspected redundancy for enhanced design verification

A verification method foe an integrated circuit includes identifying an equivalence class including a set of candidate gates suspected of exhibiting equivalent behavior and identifying one of the candidate gates as a representative gate for the equivalence class. Equivalence gates of an XOR gate are sourced by the representative gate and a candidate gate. A speculatively reduced netlist is generated by replacing the representative gate as the source gate for edges sourced by a candidate gate in the original design. The speculatively reduced netlist is then used either to verify formally the equivalence of the gates by applying a plurality of transformation engines to the speculatively reduced netlist or to perform incomplete search and, if none of the equivalence gates is asserted during the incomplete search, any verification results derived from the incomplete search can be applied to the original model.