Recognition of Fanout-free Functions

Factoring is a logic minimization technique to represent a Boolean function in an equivalent function with minimum literals. When realizing the circuit, a function represented in a more compact form has smaller area. Some Boolean functions even have equivalent forms where each variable appears exactly once, which are known as fanout-free functions. John P. Hayes (Hayes, 1975) had devised an algorithm to determine if a function can be fanout-free and construct the circuit if fanout-free realization exists. In this paper, we propose a property and an efficient technique to accelerate this algorithm. With our improvements, execution time of this algorithm is more competitive with the state-of-the-art method (Golumbic, 2001).