The probabilistic methods for power estimation in combinational circuits are classified in two categories according to the adopted gate-delay model. The zero and real gate-delay power estimation methods. Under zero delay model, assuming spatiotemporal independence among the circuit signals, the switching activity, E(sw), of a circuit node, x, is given by ) 1 ( 2 2 ) ( 1 1 0 1 x x x x p p p p sw...