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On Piercing Sets of Objects

Matthew J. Katz 1 Franck Nielsen
1 PRISME - Geometry, Algorithms and Robotics
CRISAM - Inria Sophia Antipolis - Méditerranée
Abstract : A set of objects is $k$-pierceable if there exists a set of $k$ points such that each object is pierced by (contains) at least one of these points. Finding the smallest integer $k$ such that a set is $k$-pierceable is NP-complete. In this technical report, we present efficient algorithms for finding a piercing set (i.e., a set of $k$ points as above) for several classes of convex objects and small values of $k$. In some of the cases, our algorithms imply known as well as new Helly-type theorems, thus adding to previous results of Danzer and Grünbaum who studied the case of axis-parallel boxes. The problems studied here are related to the collection of optimization problems in which one seeks the smallest scaling factor of a centrally symmetric convex object $K$, so that a set of points can be covered by $k$ congruent homothets of $K$.
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Submitted on : Wednesday, May 24, 2006 - 1:49:33 PM
Last modification on : Friday, February 4, 2022 - 3:16:09 AM
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  • HAL Id : inria-00073817, version 1



Matthew J. Katz, Franck Nielsen. On Piercing Sets of Objects. RR-2874, INRIA. 1996. ⟨inria-00073817⟩



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