Section Gen.
Variable Y: Type.
Variable R: relation2 X Y.
Variable TY: relation Y.
Let SR := comp (star S) R.
Hypothesis HR: diagram TX R (star TY) SR.
Variables X' Y': Type.
Variable TaX: relation2 X X'.
Variable TaY: relation2 Y Y'.
Variable S' : relation2 X' X'.
Variable R' : relation2 X' Y'.
Let SR' := comp (star S') R'.
Let TAX := comp (star TX) TaX.
Let TAY := comp (star TY) TaY.
Hypothesis HT:  diagram TaX S TAX (star S').
Hypothesis HRT: diagram TaX R TAY SR'.

(** Proposition 4.8 *)
Theorem diagram_star_wf_2: diagram TAX SR TAY SR'.