Lemma isiso_from_Equalizer_to_Equalizer {a b : C} {f g : C⟦a, b⟧} (E1 E2 : Equalizer f g) : is_iso (from_Equalizer_to_Equalizer E1 E2). Proof. apply (is_iso_qinv _ (from_Equalizer_to_Equalizer E2 E1)). apply are_inverses_from_Equalizer_to_Equalizer. Qed.
Require Import UniMath.Foundations.PartD. Require Import UniMath.Foundations.Propositions. Require Import UniMath.Foundations.Sets. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.Combinatorics.StandardFiniteSets. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.CategoryTheory.Core.Isos. Require Import UniMath.CategoryTheory.Limits.Graphs.Limits. Require Import UniMath.CategoryTheory.Limits.Graphs.Colimits. Require Import UniMath.CategoryTheory.Limits.Equalizers.