Cap set $r(4)$

Cap set of 20 points, no three on a line, in 4-dimensional space over the field with 3 elements, drawn as a 3 by 3 grid of 3 by 3 grids, like the cards of the game SET

The size of the largest set of points in $\mathbb{F}_3^{4}$ with no three on a line.

Value: $20$ Verified lower bound

Verified bounds

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Updates from the literature