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theorem

D3_admits_circle_linking

proved
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module
IndisputableMonolith.Foundation.AlexanderDuality
domain
Foundation
line
154 · github
papers citing
8 papers (below)

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IndisputableMonolith.Foundation.AlexanderDuality on GitHub at line 154.

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 151/-! ## Derived Facts -/
 152
 153/-- D = 3 admits circle linking (forward direction). -/
 154theorem D3_admits_circle_linking : SphereAdmitsCircleLinking 3 :=
 155  (alexander_duality_circle_linking 3).mpr rfl
 156
 157/-- Circle linking forces D = 3 (reverse direction). -/
 158theorem circle_linking_forces_D3 (D : ℕ) :
 159    SphereAdmitsCircleLinking D → D = 3 :=
 160  (alexander_duality_circle_linking D).mp
 161
 162/-- No circle linking in D ≤ 2.
 163Proof: H̃^{D-2}(S¹) = 0 for D - 2 ≤ 0, since S¹ has no nontrivial
 164reduced cohomology in non-positive degrees. -/
 165theorem no_circle_linking_low_dim (D : ℕ) (hD : D ≤ 2) :
 166    ¬SphereAdmitsCircleLinking D := by
 167  intro h
 168  have := circle_linking_forces_D3 D h
 169  omega
 170
 171/-- No circle linking in D ≥ 4.
 172Proof: H̃^{D-2}(S¹) = 0 for D - 2 ≥ 2, since S¹ has no nontrivial
 173reduced cohomology above degree 1. -/
 174theorem no_circle_linking_high_dim (D : ℕ) (hD : D ≥ 4) :
 175    ¬SphereAdmitsCircleLinking D := by
 176  intro h
 177  have := circle_linking_forces_D3 D h
 178  omega
 179
 180end AlexanderDuality
 181end Foundation
 182end IndisputableMonolith