Irredundant binate realizations of unate functions

Combinational circuits realizing unate Functions are usually simple in structure and their behaviour under the stuck-at fault model is seemingly well understood. This paper exemplifies the fact that a circuit designer may construct many peculiar irredundant circuits realizing unate functions. First, a counter-example is presented contradicting the existing notion of non-realizability of a unate function by a single-output, irredundant, binate combinational circuit. On the contrary, almost all unate functions are shown to be realizable with single-output networks that are binate as well as irredundant. A very rare example of a unate function is then cited; it has an irredundant circuit realization, none of whose primary input lines is unate.