fact: Definition istight {X : UU} (R : hrel X) := ∏ x y : X, ¬ (R x y) -> x = y.
imports: UniMath.Algebra.BinaryOperations UniMath.Foundations.Propositions UniMath.MoreFoundations.Sets UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions