Lemma apCCDRplus : ∏ x x' y y' : X, x + y ≠ x' + y' → x ≠ x' ∨ y ≠ y'. Proof. exact (apCDRplus (X := ConstructiveCommutativeDivisionRig_ConstructiveDivisionRig X)). Qed.
Require Import UniMath.MoreFoundations.Tactics.