proposition: Lemma cvg_fmap2 (T U : Type) (f : T -> U): forall (F G : set_system T), G `=>` F -> f @ G `=>` f @ F.
proof: Proof. by move=> F G H A fFA ; exact: H (preimage f A) fFA. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed