proposition: Lemma phi_principal : forall alpha beta, ap (phi alpha beta).
proof: Proof. intros alpha beta; case (phi_to_psi alpha beta);intros x (y,E); rewrite E;try constructor. Qed.
imports: EPSILON0 Arith List Omega Compare_dec Relations Wellfounded Max Tools More_nat AccP not_decreasing EPSILON0 More_nat Gamma0_prelude Gamma0_length term rpo