proposition: Lemma gcdsr1 : gcdsr (1 : {poly R}) %= 1.
proof: Proof. by rewrite polyseqC oner_neq0 /= gcdr0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(path choice fintype tuple finset ssralg) mathcomp(matrix poly) mathcomp(bigop polydiv) CoqEAL(stronglydiscrete dvdring)