proposition: Remark member_subid m n x (I : 'cV[R]_m) (J : 'cV[R]_n) : member x I -> (I <= J)%IS -> member x J.
proof: Proof. by rewrite !memberE; apply: subid_trans. 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