proposition: Lemma U_reduction (I I': uni X): sᵤ I ≡ sᵤ I' -> tᵤ I ≡ tᵤ I' -> Gammaᵤ I = Gammaᵤ I' -> Aᵤ I = Aᵤ I' -> U X I -> U 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 Undecidability.HOU.calculus(prelim terms syntax semantics equivalence typing order evaluator)