Qed.
Set Implicit Arguments.
Unset Strict Implicit.
Definition pX := cons (A:=Term A n).
Set Strict Implicit.
Unset Implicit Arguments.
Definition pO := nil (A:=Term A n).
Let consA := cons (A:=mon n).
Let nilA := nil (A:=mon n).
Let listA := list (mon n).
Hint Unfold consA nilA listA.
Fixpoint fP (a : list (Term A n)) : listA :=
match a with
| nil => nilA
| b :: p => consA (T2M b) (fP p)
end.

Theorem fP_app : forall p q : list (Term A n), fP (p ++ q) = fP p ++ fP q.
intros p; elim p; simpl in |- *; auto.