proposition: Lemma embed_sshift n (phi : form') : embed phi[sshift n] = (embed phi)[sshift n].
proof: Proof. rewrite embed_subst. apply subst_ext. intros []; unfold funcomp; now rewrite <- !sshift_spec. Qed.
imports: Undecidability.FOL.Syntax.Facts Undecidability.FOL.Syntax.Asimpl Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.Deduction.FullNDFacts Undecidability.FOL.Sets(binZF ZF) Undecidability.FOL.Reductions.PCPb_to_ZF Undecidability(Shared.ListAutomation) Morphisms Undecidability.FOL(Reductions.PCPb_to_ZFeq)