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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)2n3.\sum_i f(u_i)^2 \ll n^3.
Retained from Formal Conjectures · not edited here
Formal statements
1 open · 2 solved · 1 test
Erdős Problems says
proved (Lean)
Decision here
accepted
Checks
2 checks · 4 formal

For every finite planar point set P, the sum over its distinct determined distances of the unordered-pair distance multiplicities equals P.card.choose 2

Still unresolved: That occurrence is one of four Erdős 94 declarations Formal Conjectures publishes, and this identity does not establish the cubic distance-multiplicity conjecture.

Exact result and limitations

At lean-proofs commit 423344341fbfdf4f8f684a302c5d05379125e7dc, Erdos94.variants.sum_multiplicity proves that for every finite planar point set P, the sum over its distinct determined distances of the unordered-pair distance multiplicities equals P.card.choose 2, matching Formal Conjectures commit 94a278e06a8bcbc2e4f2935e491c0c115ec832e0. For occurrence resolution only, the exact occurrence Erdos94.erdos_94.variants.sum_multiplicity is associated with problem:erdos:94 under resolver entity root sha256:32f6e98a826da23c12c7cfcb8853e4712de130136c59f0454bd115c3fdb1e6b1. That occurrence is one of four Erdős 94 declarations Formal Conjectures publishes, and this identity does not establish the cubic distance-multiplicity conjecture.

  • An exact evidence file is bound to this Result; its recorded path remains in the technical record.
  • Occurrence association with problem:erdos:94 is navigation-only and establishes no statement identity or semantic equivalence.
  • Caveat: This proves only the elementary sum_multiplicity identity, not the cubic Erdős 94 theorem or either other variant.
  • Caveat: The Formal Conjectures build needs the mechanical Sym2.mk.uncurry to Sym2.mk API spelling change between its pinned Mathlib and lean-proofs.
  • Caveat: No external source-owner review, human review, upstream acceptance, or external adoption occurred.
  • Caveat: Producer checks are not Verification, Decision, or Standing.
Type
theoretical
Evidence
3 artifacts
Decision
accepted
Reviewed
Aug 18, 2026, 6:46 PM

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