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| Content Provider | ACM Digital Library |
|---|---|
| Author | de Berg, Mark Speckmann, Bettina Roeloffzen, Marcel |
| Abstract | We study two versions of the 2-center problem for moving points in the plane. Given a set P of n points, the Euclidean 2-center problem asks for two congruent disks of minimum size that together cover P; the rectilinear 2-center problem correspondingly asks for two congruent axis-aligned squares of minimum size that together cover P. Our methods work in the black-box KDS model, where we receive the locations of the points at regular time steps and we know an upper bound d_{max} on the maximum displacement of any point within one time step. We show how to maintain the rectilinear 2-center in amortized sub-linear time per time step, under certain assumptions on the distribution of the point set P. For the Euclidean 2-center we give a similar result: we can maintain in amortized sub-linear time (again under certain assumptions on the distribution) a (1+ε)-approximation of the optimal 2-center. In many cases---namely when the distance between the centers of the disks is relatively large or relatively small---the solution we maintain is actually optimal. We also present results for the case where the maximum speed of the centers is bounded. We describe a simple scheme to maintain a 2-approximation of the rectilinear 2-center, and we provide a scheme which gives a better approximation factor depending on several parameters of the point set and the maximum allowed displacement of the centers. The latter result can be used to obtain a 2.29-approximation for the Euclidean 2-center; this is an improvement over the previously best known bound of 8/π approx 2.55. These algorithms run in amortized sub-linear time per time step, as before under certain assumptions on the distribution. |
| Starting Page | 145 |
| Ending Page | 154 |
| Page Count | 10 |
| File Format | |
| ISBN | 9781450320313 |
| DOI | 10.1145/2462356.2462393 |
| Language | English |
| Publisher | Association for Computing Machinery (ACM) |
| Publisher Date | 2013-06-17 |
| Publisher Place | New York |
| Access Restriction | Subscribed |
| Subject Keyword | Mobile facility location Kinetic data structures Black-box model 2-center problem |
| Content Type | Text |
| Resource Type | Article |
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