Multi-level logic optimization based on pseudo maximum sets of permissible functions

The transduction method is one of the strongest multilevel logic optimization algorithms. It uses permissible functions which represent Don´t-Care conditions of a circuit. An original transduction algorithm has two sorts of sets of permissible functions: MSPF (maximum set of permissible functions) and CSPF (compatible set of permissible functions). A CSPF has the characteristics that computation time is short but optimization capability is weak. An MSPF has the opposite characteristics. The authors propose a new set of permissible functions, which is called pseudo-MSPF. It has the good characteristics of both a CSPF and an MSPF. The authors also shown that they can shorten the time for gate transformations by using pseudo-MSPFs instead of CSPFs. Experimental results show that the optimization based on pseudo-MSPFs can make logic equations with fewer literals, and shorten the total processing time than that based on CSPFs