Simplification of Toffoli networks via templates

Reversible logic functions can be realized as networks of Toffoli gates. The synthesis of Toffoli networks can be divided into two steps. First, find a network that realizes the desired junction. Second, transform the network such that it uses fewer gates, while realizing the same function. This paper addresses the second step. Transformations are accomplished via template matching. The basis for a template is a network with m gates that realizes the identity function. If a sequence in the network to be synthesized matches more than half of a template, then a transformation reducing the gate count can be applied. All templates for m≤7 are described in this paper.