fact: Definition approx_BEC_input m n (H : 'M['F_2]_(m, n)) (y : 'rV[letter]_n) (M : 'M[letter]_(m, n)) := exists2 c, c BEC( H ) y & c <=* M.
imports: mathcomp(all_ssreflect ssralg fingroup finalg perm zmodp) mathcomp(matrix) ssr_ext ssralg_ext num_occ f2 ssrR hamming tanner linearcode