Proposition cha_not_antimonotone_inv {H : complete_heyting_algebra} {x y : regular_element H} (p : ¬ x ≤ ¬ y) : y ≤ x. Proof. pose (cha_not_antimonotone p) as q. rewrite !is_regular_regular_element in q. exact q. Qed.
Require Import UniMath.MoreFoundations.All. Require Import UniMath.Algebra.BinaryOperations. Require Import UniMath.OrderTheory.Lattice.Lattice. Require Import UniMath.OrderTheory.Lattice.Bounded. Require Import UniMath.OrderTheory.Lattice.Heyting. Require Import UniMath.OrderTheory.Lattice.CompleteHeyting. Require Import UniMath.OrderTheory.Lattice.DerivedLawsCompleteHeyting.