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ARRANGEMENTS OF HOMOTHETS OF A CONVEX BODY

Published online by Cambridge University Press:  09 August 2017

Márton Naszódi
Affiliation:
Department of Geometry, Lorand Eötvös University, Pazmány Péter Sétany 1/C Budapest, 1117, Hungary email [email protected]
János Pach
Affiliation:
École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland email [email protected] Rényi Institute, Budapest, Hungary
Konrad Swanepoel
Affiliation:
Department of Mathematics, London School of Economics and Political Science, Houghton Street, London WC2A 2AE, U.K. email [email protected]
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Abstract

Answering a question of Füredi and Loeb [On the best constant for the Besicovitch covering theorem. Proc. Amer. Math. Soc.121(4) (1994), 1063–1073], we show that the maximum number of pairwise intersecting homothets of a $d$-dimensional centrally symmetric convex body $K$, none of which contains the center of another in its interior, is at most $O(3^{d}d\log d)$. If $K$ is not necessarily centrally symmetric and the role of its center is played by its centroid, then the above bound can be replaced by $O(3^{d}\binom{2d}{d}d\log d)$. We establish analogous results for the case where the center is defined as an arbitrary point in the interior of $K$. We also show that, in the latter case, one can always find families of at least $\unicode[STIX]{x1D6FA}((2/\sqrt{3})^{d})$ translates of $K$ with the above property.

Type
Research Article
Copyright
Copyright © University College London 2017 

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