Proposition make_is_regular_element {H : complete_heyting_algebra} {x : H} (p : ¬ ¬ x ≤ x) : is_regular_element x. Proof. use cha_le_antisymm. - apply cha_not_not. - exact p. 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.