01
The problem
Let f_k(n) be minimal such that if n points in ℝ^2 have no k+1 points on a line then there must be at most f_k(n) many lines containing at least k points. Is it true that f_k(n)=o(n^2) for k≥ 4?
Open since1963source estimate
Last checked2026.07.26Catalog verification
02
Reward offers
Offer 01$100Paul Erdős / Combinatorics Foundation
DocumentedA 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.