PPL 036 / 177 permanent IDsPrize Problem Ledger · PPLChecked 2026.07.26
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Prize Problem LedgerErdősPPL 036Erdős Problem #104

Permanent problem IDPPL 036

Verified openErdősconjecture

Geometry

Erdős Problem #104

Given n points in ℝ^2 the number of distinct unit circles containing at least three points is o(n^2).

geometry
01

The problem

Given n points in ℝ^2 the number of distinct unit circles containing at least three points is o(n^2).

Open since1975source estimate
Last checked2026.07.26Catalog verification
02

Reward offers

Offer 01$100Paul Erdős / Combinatorics Foundation
Documented

A solution must appear in a reputable journal, with documentation that Erdős offered the displayed amount. Claims are administered by the Combinatorics Foundation; erdosproblems.com does not pay awards.

Award source ↗Rules ↗
03

Sources & reading

3 unique reference linksCanonical problem page Claim or award rules OEIS A003829
04

Related open targets

GeometryErdős Problem #604PPL 067 · $500 · 69 years openGeometryErdős Problem #89PPL 083 · $500 · 80 years openGeometryErdős Problem #101PPL 034 · $100 · 52 years open