proposition: Lemma islunit_setofendabgr_un1 {G : abgr} : islunit (@ringofendabgr_op2 G) setofendabgr_un1.
proof: Proof. intro f. use total2_paths_f. - apply funextfun. intro x. reflexivity. - apply isapropismonoidfun. Defined.
imports: UniMath.MoreFoundations.Tactics UniMath.Algebra.RigsAndRings UniMath.Algebra.Groups UniMath.Algebra.Monoids