proposition: Lemma eqid_trans m n k (J : 'cV_n) (I : 'cV[R]_m) (K : 'cV_k) : (I :=: J -> J :=: K -> I :=: K)%IS.
proof: Proof. by move=> IJ JK; apply/eqidP; rewrite !IJ !JK. 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