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A note on large Kakeya sets

  • Maarten De Boeck EMAIL logo and Geertrui Van de Voorde
From the journal Advances in Geometry

Abstract

A Kakeya set π“š in an affine plane of order q is the point set covered by a set 𝓛 of q + 1 pairwise non-parallel lines. By Dover and Mellinger [6], Kakeya sets with size at least q2 – 3q + 9 contain a large knot, i.e. a point of π“š lying on many lines of 𝓛. We improve on this result by showing that Kakeya set of size at least β‰ˆ q2 – q q + 32 q contain a large knot, and we obtain a sharp result for planes containing a Baer subplane.

Keywords: Kakeya set; k-knots
MSC 2010: 05B25; 51E15; 51E20
  1. Communicated by: J. Bamberg

Acknowledgements

This research was partially carried out when the first author was visiting the School of Mathematics and Statistics at the University of Canterbury. He wants to thank the School, and in particular the second author, for their hospitality.

We thank the anonymous reviewers for their detailed suggestions.

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Received: 2019-08-09
Revised: 2020-01-15
Published Online: 2021-07-06
Published in Print: 2021-07-27

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