Definition composable_pairs_rel {C : category} (PB : Pullbacks C) {x : C} (R : internal_relation x) : C := PB _ _ _ (internal_relation_src R) (internal_relation_tar R).
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.CategoryTheory.Core.Prelude. Require Import UniMath.CategoryTheory.Limits.Pullbacks. Require Import UniMath.CategoryTheory.Limits.Coequalizers. Require Import UniMath.CategoryTheory.RegularAndExact.RegularCategory.