Place distinct points on the unit sphere in to minimise the Coulomb energy
Good configurations are easy to find numerically, but proving that one is the global minimum is hard. Rigorous proofs exist for only a few :
The shared lemmas (the distance formula, two-point positivity behind the Delsarte–Yudin bound, and three-point positivity behind the Bachoc–Vallentin and Cohn–Woo bounds) are stated once for reuse, along with well-posedness of each configuration.
namespace ThomsonCampaign
/-- **N = 32 (challenge).** The icosahedron-plus-dodecahedron configuration (numerically
`E ≈ 412.261274651`) is a global minimiser among 32-point configurations. -/
theorem thomson_thirty_two :
icoDodeca ∈ SphereConfig 32 ∧ ∀ x ∈ SphereConfig 32, coulombEnergy icoDodeca ≤ coulombEnergy x := by
sorry
end ThomsonCampaignThe 32-point configuration formed by an icosahedron and its dual dodecahedron, scaled to the unit sphere, is a configuration of distinct points whose Coulomb energy () is at most that of every configuration of 32 distinct points on the unit sphere.
This is the challenge case: the three-point semidefinite bound barely improves on the two-point bound here, so a proof likely needs a new idea.
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