Minimization of fanout in switching networks

The problem of finding the minimum amount of fanout needed to realize a switching function f is investigated. Fanout-free functions are defined, and necessary and sufficient conditions for a function to be fanout-free are derived. A measure τ(f) called the input fanout index, is introduced which represents the minimum number of input variables that fan out in any realization off. It is shown that τ(f), can be determined from the prime implicants and implicates off. Another measure of fanout µ(f), which is the minimum number of signal lines that must fan out in any network realizing f is defined, and some of the properties of µ(f) are examined.