On diagnostic tests of contact break for contact circuits

We prove that, for $n\geqslant 2$, one can implement each Boolean function on $n$ variables by a two-pole contact circuit which is irredundant and allows a diagnostic test with a length not exceeding $n+k(n-2)$ under not more than $k$ contact breaks. We obtain that, under $k=k(n)\leqslant 2^{n-4}$, for almost all Boolean functions on n variables, the least possible length of such a test does not exceed $2k+2$.