fact: Definition discard : discardT F n [finType of 'rV_k] := [ffun x => x *m 'D^T].
imports: mathcomp(all_ssreflect ssralg poly polydiv fingroup perm) mathcomp(finalg zmodp matrix mxalgebra mxpoly vector) ssr_ext ssralg_ext poly_ext f2 hamming decoding channel_code