Erdős problem 503 · problems.science

What is the size of the largest $A \subseteq \mathbb{R}^n$ such that every three points from $A$ determine an isosceles triangle? That is, for any three points $x$ , $y$ , $z$ from $A$ , at least two of the distances $|x - y|$ , $|y - z|$ , $|x - z|$ are equal.

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FormalConjectures/ErdosProblems/503.lean

Formal Conjectures

FormalConjectures/ErdosProblems/503.leanErdos503.erdos_5031 lineExact file

1∀ (n : ℕ), IsGreatest {x | ∃ A, ∃ (_ : A.IsIsosceles), A.ncard = x} sorry

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AI collaborating with humans
Erdős AI contributions wiki · 27-28 May, 2026
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Przemek Chojecki, Junnosuke Koizumi, RealBelgian
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AI collaborating with humans
Erdős AI contributions wiki · 22 Apr, 2026
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Aristotle, GPT-5.4 Pro
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Przemek Chojecki
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