proposition: Lemma subst_step s t sigma: s > t -> sigma • s > sigma • t.
proof: Proof. induction 1 in sigma |-*; cbn; eauto. - econstructor. subst. now asimpl. Qed.
imports: Undecidability.HOU(calculus.prelim calculus.terms calculus.syntax std.std) Morphisms Lia FinFun