proposition: Lemma typ_inum_subproof (xt : Itv.typ) (x : Itv.sort xt) : Itv.spec (Itv.sort_itv xt) x.
proof: Proof. by move: xt x => []. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool) mathcomp(ssrnat eqtype choice order ssralg ssrnum ssrint) mathcomp(interval) mathcomp(mathcomp_extra boolp) signed