Signature Minimisation


From Undecidability.DiophantineConstraints Require Import H10C H10C_undec.
From Undecidability.FOL.Syntax Require Import Core BinSig.
From Undecidability.FOL Require Semantics.Tarski.FragmentFacts Deduction.FragmentNDFacts Semantics.Kripke.FragmentCore
                                Semantics.FiniteTarski.Fragment.
From Undecidability.FOL Require Semantics.Tarski.FragmentFacts Deduction.FullNDFacts.
From Undecidability.FOL.Undecidability.Reductions Require H10UPC_to_FOL_minimal.
From Undecidability.FOL.Undecidability.Reductions Require H10UPC_to_FOL_full_fragment H10UPC_to_FSAT.
From Undecidability.Synthetic Require Import Definitions Undecidability ReducibilityFacts.

Set Default Proof Using "Type".

Definition minimalForm (ff:falsity_flag) := @form sig_empty sig_binary FragmentSyntax.frag_operators ff.

Section full_fragment.
  Import H10UPC_to_FOL_full_fragment.
  Import Undecidability.FOL.Semantics.Tarski.FullFacts.

  Lemma minSignatureValiditiyUndec : @undecidable (@form sig_empty sig_binary FullSyntax.full_operators falsity_on) valid.
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    exact fullFragValidReduction.
  Qed.
End full_fragment.

Section general.
  Import H10UPC_to_FOL_minimal.
  Import Semantics.Tarski.FragmentFacts Deduction.FragmentNDFacts Semantics.Kripke.FragmentCore.

  Lemma minValidityUndec : undecidable (fun k : minimalForm falsity_off => valid k).
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    exact validReduction.
  Qed.

  Lemma minKripkeValidityUndec : undecidable (fun k : minimalForm falsity_off => kvalid k).
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    exact kripkeValidReduction.
  Qed.

  Definition int_provable (phi : minimalForm falsity_off) : Prop := nil M phi.
  Definition class_provable (phi : minimalForm falsity_off) : Prop := nil C phi.

  Lemma minProvabilityUndec : undecidable int_provable.
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    exact proveReduction.
  Qed.

  Lemma minClassicalProvabilityUndec : undecidable class_provable.
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    exact classicalProveReduction.
  Qed.

  Lemma minSatisfiabilityUndec : undecidable (fun k : minimalForm falsity_on => satis k).
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_compl_undec).
    apply satisReduction.
  Qed.

  Lemma minKripkeSatisfiabilityUndec : undecidable (fun k : minimalForm falsity_on => ksatis k).
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_compl_undec).
    apply kripkeSatisReduction.
  Qed.

End general.

Section finite.
  Import H10UPC_to_FSAT.
  Import Semantics.FiniteTarski.Fragment.
  Import Semantics.Tarski.FragmentFacts.
  Lemma minFiniteSatisfiabilityUndec : undecidable FSAT.
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    eapply reduces_transitive.
    * eexists. apply fsat_reduction.
    * eexists. apply frag_reduction_fsat.
  Qed.
  Lemma minDiscreteFiniteSatisfiabilityUndec : undecidable FSATd.
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    eapply reduces_transitive.
    * eexists. apply fsatd_reduction.
    * eexists. apply frag_reduction_fsatd.
  Qed.
  Lemma minDiscreteClosedFiniteSatisfiabilityUndec : undecidable FSATdc.
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    eapply reduces_transitive.
    * eexists. apply fsatdc_reduction.
    * eexists. apply frag_reduction_fsatdc.
  Qed.

  Lemma minDiscreteClosedFullFiniteSatisfiabilityUndec : undecidable Full.FSATdc.
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_undec).
    eexists. apply fsatdc_reduction.
  Qed.

  Lemma minFiniteValidityUndec : undecidable FVAL.
  Proof.
    apply (undecidability_from_reducibility H10UPC_SAT_compl_undec).
    eapply reduces_transitive.
    * eexists. apply fval_reduction.
    * eexists. apply frag_reduction_fval.
  Qed.

  Lemma minFiniteValidityConjecture : undecidable (@FVAL _ _ falsity_off).
  Abort.

End finite.