Escaping Local Minima in Logic Synthesis

In this report, we continue studying Logic Synthesis Preserving Specification (LSPS). Given a combinational circuit N and its partition into subcircuits N1,..,Nk (this partition is called a specification of N), LSPS optimizes N by replacing each subcircuit Ni with toggle equivalent subcircuit Ni. As we showed before, LSPS is scalable. In this report, we demonstrate that LSPS can be also viewed as an elegant way to address the local minimum entrapment problem. The latter remains a thorny issue for the heuristic algorithms for solving hard combinatorial problems. We also discuss finding a “good” specification of a circuit. In particular, we show that for narrow circuits there is a natural specification subcircuits of which form a cascade. For a wide circuit, a good specification describes a “narrow” change of this circuit. In this report, we only give various “theoretical” arguments in favor of LSPS. The preliminary experimental results of LSPS can be found in [6][7].