proposition: Lemma step_subst P Q σ τ : step P Q -> step (subst_term σ τ P) (subst_term σ τ Q).
proof: Proof. induction 1 in σ, τ |- *; cbn; asimpl; eauto using step. - eapply step_ext_2. econstructor. now_asimpl. - eapply step_ext_2. econstructor. now_asimpl. Qed.
imports: Undecidability.SystemF.SysF Undecidability.SystemF.Autosubst.syntax Undecidability.SystemF.Autosubst.unscoped Undecidability.SystemF.Util.typing_facts Undecidability.SystemF.Util.term_facts Coq.Relations.Relation_Operators