proposition: Lemma prod_nbhs_singleton (p : T * U) (A : set (T * U)) : prod_nbhs p A -> A p.
proof: Proof. by move=> [QR [/nbhs_singleton Qp1 /nbhs_singleton Rp2]]; apply. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed