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Combinatorial Geometry Open

No-Three-In-Line Problem

What is the maximum number of points that can be placed in the n × n grid so that no three are collinear? A construction of 2n is classical; whether 2n is always achievable for every n is open in general.

Impact
47 /100
Funded
$2,036.78
Donors
41
Of goal
27%
$2,036.78 raised Compute goal $7,500

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  1. Verification

    Construction archive re-verified up to n = 50,000

    Every archived 2n configuration through n = 50,000 was rechecked for collinearity with exact integer arithmetic.

    Verification method

    Exact 2×2 minor tests on all triples via batched integer determinants; failures would halt the job. Zero failures in range.

    Checks: 2n constructions known for vast ranges of n

    Arbiter verification desk

  2. Validated increment

    2n constructions known for vast ranges of n

    Explicit constructions give 2n points with no three collinear for all n up to very large computational bounds and for infinite parametric families. A uniform construction for every n is still missing.

    Previous best

    2n for many infinite families and checked ranges

    New certified

    Extended certified range + new parametric families

    Public literature + Arbiter construction search

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