We investigate left-shifts of variables in Boolean functions and stuck-at faults. Some bounds of Shannon functions are established, producing the minimum test lengths for detection and diagnosis of any n-variable Boolean function with respect to a given fault source. (The Shannon function of the test length is the maximum of the minimum test lengths over all n-variable Boolean functions.) A left-shift in an n-variable Boolean function simultaneously increments the indexes of all the variables by a natural number and substitutes some constants for variables with indexes greater than n. The Shannon function of the relevant test is shown to be exactly of length 2; the order of growth of the Shannon function of the length of the diagnosis test is \( \Theta \left(\sqrt{2^n}\right). \) With the variables left-shifted by k places, 1 ≤ k ≤ n, the Shannon function \( {L}^{diagn}\left({U}_{n,k}^{shifts},n\right) \) of the length of the complete diagnosis test has the following bounds: \( \min \left({2}^k-1,{2}^{n-k}\right)\le {L}^{diagn}\left({U}_{n,k}^{shifts},n\right)\le \min \left({2}^k,{2}^{n-k}+1\right). \) The article also considers local stuck-at faults of multiplicity k on the inputs of k-input, one-output circuits realizing a Boolean function. An asymptotic expression is derived for the log Shannon function of the diagnosis test length \( {\log}_2{L}^{diagn}\left({U}_k^{lc},n\right)\sim k\ \mathrm{as}\ n\to \infty, k=k(n)\to \infty, \kern1em 1\le k\le n/2,{\log}_2n=o(k). \) An asymptotic lower bound of the Shannon function of the diagnosis test length with stuck-at faults on circuit inputs is shown to be Ldiagn(Uc, n) ≥ 2 ⋅ 2[n/2] ⋅ (1 + o(1)) as n → ∞ .
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Translated from Prikladnaya Matematika i Informatika, No. 64, 2020, pp. 79–85.
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Antyufeev, G.V., Romanov, D.S. Tests with Stuck-At and Shift Faults on Circuit Inputs. Comput Math Model 31, 494–500 (2020). https://doi.org/10.1007/s10598-021-09511-4
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DOI: https://doi.org/10.1007/s10598-021-09511-4