theorem
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metaCost_symm
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83
84/-- **(L2) Non-Contradiction** for the meta-cost: the comparison is
85symmetric in its arguments. -/
86theorem metaCost_symm (R S : MetaCarrier) : metaCost R S = metaCost S R := by
87 unfold metaCost
88 by_cases h : R = S
89 · subst h; rfl
90 · have hSR : ¬ S = R := fun h' => h h'.symm
91 simp [h, hSR]
92
93/-- **(L3a) Totality** for the meta-cost: defined on every pair of
94realizations, returns a value (the function type signature). -/
95theorem metaCost_total (R S : MetaCarrier) : ∃ c : ℕ, metaCost R S = c :=
96 ⟨metaCost R S, rfl⟩
97
98/-- The meta-cost is zero iff the realizations are definitionally
99equal. -/
100theorem metaCost_eq_zero_iff (R S : MetaCarrier) :
101 metaCost R S = 0 ↔ R = S := by
102 unfold metaCost
103 by_cases h : R = S
104 · simp [h]
105 · simp [h]
106
107/-! ## Forced-Arithmetic Invariance: The Meta-Theorem -/
108
109/-- **The meta-theorem reified.** For any two realizations, the canonical
110equivalence between their forced arithmetic objects exists. This is
111exactly `universal_forcing_via_NNO`, packaged as the comparison law of
112the meta-realization. -/
113noncomputable def metaForcedArithmeticInvariance (R S : MetaCarrier) :
114 R.Orbit ≃ S.Orbit :=
115 universal_forcing_via_NNO R S
116