(* qq u. gu : IIi Fi --p(domu)--> F(domu) --Fu--> ku (= F(codomu)) *)

Definition Thl_gu (u : Arrs J) := Proj1 Thl_l_Fi (Dom u) o FMor F (Arrow u).(* donc E! g : IIi Fi -> ||u F(codomu) tq ... *)

Definition Thl_g := Pd1_diese Thl_l_Fu Thl_gu.

(* Specifications: *)
Lemma Thl_diag2 : forall u : Arrs J, Thl_gu u =_S Thl_g o Proj1 Thl_l_Fu u.