1. A method of generating a candidate permutation of a permutation group associated with a first function and including a plurality of symmetric subgroups to match a candidate cluster to cells in an existing cell library, comprising the steps of: (a) selecting a first symmetric subgroup; (b) selecting a second symmetric subgroup; (c) determining a second order signature for the first and second symmetric subgroups; (d) comparing the second order signature to a parallel second order signature for a second function in a technology library; and (e) if the second order signatures are equivalent, defining an intermediate permutation including the first and second symmetric subgroups, and if there are no unselected symmetric subgroups, returning the intermediate permutation as the candidate permutation.