proposition: Lemma fixedSpace_limg f U : (U <= fixedSpace f -> f @: U = U)%VS.
proof: Proof. move/fixedSpacesP=> cUf; apply/vspaceP=> x. by apply/memv_imgP/idP=> [[{}x Ux ->] | Ux]; last exists x; rewrite ?cUf. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)