# On Piercing Sets of Objects

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 $K$.
Keywords :
Type de document :
Rapport
RR-2874, INRIA. 1996
Domaine :

https://hal.inria.fr/inria-00073817
Contributeur : Rapport de Recherche Inria <>
Soumis le : mercredi 24 mai 2006 - 13:49:33
Dernière modification le : samedi 27 janvier 2018 - 01:31:31
Document(s) archivé(s) le : dimanche 4 avril 2010 - 21:31:12

### Identifiants

• HAL Id : inria-00073817, version 1

### Citation

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

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