Interchangeable boolean functions and their effects on redundancy in logic circuits

A new concept of interchangeability of boolean functions under stuck-at faults in logic circuits is introduced in this paper. Two boolean functions F₁ and F₂ are said to be interchangeable if there exist two irredundant combinational networks N ₁ and N₂ realizing F₁ and F₂ respectively, such that under some single/multiple stuck-at fault f₁(f₂) in N₁(N₂), the faulty network realizes F₂(F₁). It has been shown that an infinite family of such interchangeable pairs of functions exist, and they play an important role in determining several new types of redundancy in combinational and sequential circuits