Supporting results for pointwise provable equality.
Graph witnesses for the second-incompleteness obstruction.
theorem
PointwiseComposition.FailureOfComposition.graph_noncongruence_via_godel
(T : FFL.FirstOrder.ArithmeticTheory)
[FFL.FirstOrder.Theory.ฮโ T]
[FFL.Entailment.Consistent T]
[๐๐ โผ T]
:
โ (F : ProofSearch.Graph) (I : ProofSearch.Graph) (G : ProofSearch.Graph),
ProofSearch.Functional F โง ProofSearch.Functional I โง ProofSearch.Functional G โง ProofSearch.Pointwise T F I โง ยฌProofSearch.Pointwise T (ProofSearch.comp F G) (ProofSearch.comp I G)
The second-incompleteness route to noncongruence for functional graphs.
theorem
PointwiseComposition.FailureOfComposition.pa_graph_noncongruence_via_godel :
โ (F : ProofSearch.Graph) (I : ProofSearch.Graph) (G : ProofSearch.Graph),
ProofSearch.Functional F โง ProofSearch.Functional I โง ProofSearch.Functional G โง ProofSearch.Pointwise ๐๐ F I โง ยฌProofSearch.Pointwise ๐๐ (ProofSearch.comp F G) (ProofSearch.comp I G)