proposition: Lemma seq1_free v : free [:: v] = (v != 0).
proof: Proof. by rewrite /free span_seq1 dim_vline; case: (~~ _). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)