Boolean Function Matching using Walsh Spectral Decision Diagrams

This paper investigates two approaches for Boolean matching using NPN equivalence matching. Luks' hypergraph method is implemented and compared to the Walsh spectral decision diagram (SDD) method that we propose here. Both methods determine a canonical representation for each NPN equivalence class. The target functions are then transformed into a canonical representation and compared to the representative canonical forms for the NPN classes. This paper presents the implementation and results of the spectral method in detail. It is shown that the spectral method compares favorably to Luks' method and is better in terms of computational requirements for large functions