proposition: Lemma addid0 m n (I : 'cV[R]_m) : (I +i (0 : 'cV[R]_n) :=: I)%IS.
proof: Proof. by apply/eqidP; rewrite sub_addid0r sub_add0rid. 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