fact: Definition GEN' : 'M_(n - m, n) := castmx (erefl, subnK (Hamming.dim_len m')) (row_mx 1%:M (- CSM)^T).
imports: mathcomp(all_ssreflect ssralg fingroup finalg perm zmodp) mathcomp(matrix mxalgebra vector) mathcomp(Rstruct) realType_ext ssr_ext ssralg_ext f2 linearcode natbin ssrR hamming bigop_ext fdist proba channel channel_code decoding binary_symmetric_channel