Lemma istrans_filter_le {X : UU} : ∏ F G H : PreFilter X, filter_le F G → filter_le G H → filter_le F H. Proof. intros F G H Hfg Hgh A Fa. apply Hfg, Hgh, Fa. Qed.
Require Import UniMath.Foundations.Preamble. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.MoreFoundations.PartA.