proposition: Lemma continuous_subspaceW {U} A B (f : T -> U) : A `<=` B -> {within B, continuous f} -> {within A, continuous f}.
proof: Proof. by move=> ? ctsF ? ? ?; apply: (@nbhs_subspace_subset A B) => //; exact: ctsF. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed