proposition: Lemma limg_dim_eq f U : (U :&: lker f = 0)%VS -> \dim (f @: U) = \dim U.
proof: Proof. by rewrite -(limg_ker_dim f U) => ->; rewrite dimv0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)