proposition: Lemma prod_nbhs_nbhs (p : T * U) (A : set (T * U)) : prod_nbhs p A -> prod_nbhs p (prod_nbhs^~ A).
proof: Proof. move=> [QR [/nbhs_interior p1_Q /nbhs_interior p2_R] sQRA]. by exists (QR.1^°, QR.2^°) => // ??; exists QR. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed