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Kakeya Set


A Kakeya set in R^n is a set containing a line segment of length 1 in every direction. The definition specifies the presence of the segments; continuous rotation of a needle within the set is the separate requirement in the Kakeya needle problem.

Choudhuri (2026) proved that every Kakeya set in R^4 has Hausdorff dimension at least (13)/4-(12951-54sqrt(10593))/(41972)=3.073854.... The argument combines the three-dimensional Kakeya theorem with a planebrush estimate.


See also

Hausdorff Dimension, Kakeya Maximal Conjecture, Kakeya Maximal Function, Kakeya Needle Problem, Line Segment, Perron Tree

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References

Choudhuri, M. R. "New Bound on the Hausdorff Dimension of Kakeya Sets in R^4." 30 Aug 2026. https://arxiv.org/abs/2610.12480.Wolff, T. H. Lectures on Harmonic Analysis. (Ed. I. Łaba and C. Shubin). Providence, RI: Amer. Math. Soc., 2003. https://doi.org/10.1090/ulect/029.

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Kakeya Set

Cite this as:

Weisstein, Eric W. "Kakeya Set." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/KakeyaSet.html

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