Variables R R': relation2 X Y.
Variable TY TY': relation Y.
Hypothesis HR: diagram TX R (star TY) (comp (star S) R).
Hypothesis HR': diagram TX' R (comp (star TY) TY') (comp (star S) R').

(** Proposition 4.4 *)
Theorem diagram_plus_wf_2: diagram (comp (star TX) TX') (comp (star S) R) (comp (star TY) TY') (comp (star S) R').
End PlusWf.