proposition: Lemma eqid_sym m n (I: 'cV[R]_n) (J: 'cV[R]_m) : (I :=: J)%IS -> (J :=: I)%IS.
proof: Proof. by move=> /eqidP; rewrite andbC => /eqidP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice fingroup) mathcomp(matrix bigop zmodp mxalgebra poly) ssrcomplements