Definition istight {X : UU} (R : hrel X) := ∏ x y : X, ¬ (R x y) → x = y.
Require Import UniMath.Foundations.Propositions. Require Import UniMath.MoreFoundations.Sets. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.MoreFoundations.DecidablePropositions.