Fix polynoms g1(x), g2(x) over F_2[x]. **Question:** How to find minimum over polynoms p(x) of the: *HammingWeight(p(x) g1(x) ) + HammingWeight(p(x) g2(x) )* ? By HammingWeight of polynom I mean number of non-zero monoms, let me denote by || *|| Trivial estimate: minimum <= || g1(x)|| + || g2(x)||. Proof just put p(x) =1. Numerical observation: apparently there are polynoms g1,g2 where this estimate is exact. Can this be true ? --- **Modified question 1** If I put restriction deg(p(x)) < N with N>> deg(gi) will it change minimum ? if yes what can be said about it ? **Modified question 2** If I put restriction deg(p(x)) < N and moreover will consider multiplication in the factor F_2[x]/ (x^N-1) will it change minimum ? if yes what can be said about it ? -------- **Error-correcting codes formulation** The question is how to calculate minimal distance of [non-recursive convolutional code][1] ? If I put restriction deg(p) < N this corresponds to various truncations of them. In particular working with F_2[x]/ (x^N-1) corresponds to "tail-biting". ------ PS This is completely rewritten version of the previous question. [1]: http://en.wikipedia.org/wiki/Convolutional_code#Recursive_and_non-recursive_codes