# No-Three-in-Line Problem

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In 1917, Henry Dudeney asked for the maximum number of points selectable from an × grid so that no three points are collinear. Obviously, no more than two points can be selected from any row or column, so the maximal amount of points is . Calling a solution an × grid with a maximal selection of points with no three points collinear, a 52×52 grid with 104 selected points is the largest known solution. This Demonstration gives all solutions up to order 18×18, and some of the known solutions for larger-sized grids.

Contributed by: Ed Pegg Jr (November 2013)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

Solution data for orders 17 and 18 are from [2]. All other solution data is from [1].

References

[1] A. Flammenkamp. "The No-Three-in-Line Problem." (Mar 3, 1998) wwwhomes.uni-bielefeld.de/achim/cgi/no3in/readme.html.

[2] B. Chaffin. "No Three In Line Problem." (Apr 4, 2006) wso.williams.edu/~bchaffin/no_three_in _line/index.htm.

[3] Wikipedia. "No-Three-in-Line Problem." (Nov 5, 2013) en.wikipedia.org/wiki/No-three-in-line_problem.

## Permanent Citation

"No-Three-in-Line Problem"

http://demonstrations.wolfram.com/NoThreeInLineProblem/

Wolfram Demonstrations Project

Published: November 8 2013