theorem
proved
cube_uniqueness
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IndisputableMonolith.Meta.LedgerUniqueness on GitHub at line 136.
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133
134/-- The cube Q₃ is the unique linking-compatible polytope.
135 (Reformulated: Linking structure implies D=3) -/
136theorem cube_uniqueness :
137 ∀ D : ℕ, (linkingNumber D ≠ 0) ↔ D = 3 := by
138 intro D
139 constructor
140 · intro h
141 unfold linkingNumber at h
142 split_ifs at h with hD
143 · exact hD
144 · contradiction
145 · intro h
146 rw [h]
147 unfold linkingNumber
148 simp
149
150/-! ## 8-Tick Uniqueness -/
151
152/-- A Gray code cycle of length T on D dimensions. -/
153def grayCodeCycleLength (D : ℕ) : ℕ := 2^D
154
155/-- For D=3, the minimal complete cycle is 8 = 2³. -/
156theorem eight_tick_minimal :
157 grayCodeCycleLength 3 = 8 := by
158 unfold grayCodeCycleLength
159 norm_num
160
161/-- No shorter cycle covers the cube. -/
162theorem no_shorter_cycle :
163 ∀ T : ℕ, T < 8 → ¬∃ (cycle : Fin T → Fin 8), Function.Bijective cycle := by
164 intro T hT
165 intro ⟨cycle, hBij⟩
166 -- Bijection requires |domain| = |codomain|