proposition: Lemma subrid m i (I : 'cV[R]_m) : ((I i 0)%:M <= I)%IS.
proof: Proof. apply/subidP; exists (delta_mx 0 i); rewrite -rowE. by apply/colP=> j; rewrite !mxE ord1 mulr1n. 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