Lemma free_abgr_hrel_intro {X : hSet} (l1 l2 : free_gr X) : free_abgr_hrel X (l1 * l2) (l2 * l1). Proof. apply wittohexists with l1. split with l2. split; reflexivity. Defined.
Require Import UniMath.MoreFoundations.Subtypes. Require Import UniMath.MoreFoundations.Sets. Require Import UniMath.Algebra.Monoids. Require Import UniMath.Algebra.Groups. Require Import UniMath.Algebra.IteratedBinaryOperations. Require Import UniMath.Combinatorics.Lists.