proposition: Lemma RintP x : reflect (exists z, x = z%:~R) (x \in Rint).
proof: Proof. by apply/(iffP idP) => [/asboolP[z /eqP]|[z]] ->; [|apply/asboolP]; exists z. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra) mathcomp(mathcomp_extra boolp classical_sets set_interval) Setoid