proposition: Lemma OU_reduction n (I I': orduni n X): s₀ I ≡ s₀ I' -> t₀ I ≡ t₀ I' -> Gamma₀ I = Gamma₀ I' -> A₀ I = A₀ I' -> OU n X I -> OU n X I'.
proof: Proof. intros H1 H2 H3 H4; intros (Delta & sigma & T & N); exists Delta; exists sigma; split. rewrite <-H3; trivial. now rewrite <-H1, <-H2, N. Qed.
imports: List Lia Morphisms Undecidability.HOU(std.std calculus.calculus unification.higher_order_unification unification.systemunification)