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Erdős problem 94

Suppose nn points in R2\mathbb{R}^2 determine a convex polygon and the set of distances between them is {u1,…,ut}\{u_1,\ldots,u_t\}. Suppose uiu_i appears as the distance between f(ui)f(u_i) many pairs of points. Then ∑if(ui)2≪n3.\sum_i f(u_i)^2 \ll n^3.

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4 retained statements36c6d0fef71a

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FormalConjectures/ErdosProblems/

94.lean

Retained formal statement3 of 4

Erdős and Fishburn also make the stronger conjecture that ∑f(ui)2\sum f(u_i)^2 is maximal for the regular nn-gon (for large enough nn).

FormalConjectures/ErdosProblems/94.leanErdos94.erdos_94.variants.regular_ngon7 linesExact file
∀ᶠ (n : ℕ) in Filter.atTop,  ∀ (P : Finset (EuclideanSpace ℝ (Fin 2))),    P.card = n →      EuclideanGeometry.ConvexIndep ↑P →        ∑ u ∈ EuclideanGeometry.distanceSet P, ↑(EuclideanGeometry.distanceMultiplicity P u) ^ 2 ≤          ∑ u ∈ EuclideanGeometry.distanceSet (Erdos94.regularNGon n),            ↑(EuclideanGeometry.distanceMultiplicity (Erdos94.regularNGon n) u) ^ 2
OpenStatement only, no proofformal statement reference