proposition: Lemma modulefun_unel {R : ring} {M N : module R} (f : R-mod(M, N)) : f (unel M) = unel N.
proof: Proof. rewrite <- (module_mult_0_to_0 (unel M)). rewrite ((modulefun_to_islinear f) ringunel1 (unel M)). rewrite (module_mult_0_to_0 _). reflexivity. Defined.
imports: UniMath.MoreFoundations.Tactics UniMath.Algebra.RigsAndRings UniMath.Algebra.Groups UniMath.Algebra.Monoids