proposition: Lemma algid_neq0 A : algid A != 0.
proof: Proof. have /andP[/has_algidP[u [Au nz_u _]] _] := valP A. by apply: contraNneq nz_u => e0; rewrite -(algidr Au) e0 mulr0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype div tuple finfun bigop ssralg) mathcomp(finalg zmodp matrix vector poly)