proposition: Lemma embed_sshift n (phi : form') : embed phi[sshift n] = (embed phi)[sshift n].
proof: Proof. rewrite embed_subst. apply subst_ext. now intros []. Qed.
imports: Undecidability.FOL.ZF Undecidability.FOL.Syntax.Facts Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.Sets(minZF ZF) Undecidability.FOL.Sets.ZF Undecidability.FOL.Reductions.PCPb_to_ZF Undecidability(Shared.ListAutomation)