proposition: Lemma and_equiv { p : peirce } (phi psi phi' psi' : form') A : (A ⊢ phi <-> A ⊢ phi') -> (A ⊢ psi <-> A ⊢ psi') -> (A ⊢ phi ∧ psi) <-> (A ⊢ phi' ∧ psi').
proof: Proof. intros H1 H2. split; intros H % CE; apply CI; intuition. 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)