Proposition cha_disj_not {H : complete_heyting_algebra} (x y : H) : (¬x ∨ ¬y) ≤ ¬(x ∧ y). Proof. use cha_max_le_case. - use cha_not_antimonotone. use cha_min_le_l. - use cha_not_antimonotone. use cha_min_le_r. 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.