forall e (f g : A -> B), close e f g -> forall x, close e (f x) (g x). Proof. intros e f g E x;revert E;apply (Trunc_ind _);intros [d [d' [E1 E2]]]. rewrite E1;apply rounded_plus;trivial. Qed.
Require Import Import NatPair.Instances. Import Quoting.Instances.