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| Content Provider | ACM Digital Library |
|---|---|
| Author | Pach, János Smorodinsky, Shakhar Sharir, Micha Pinchasi, Rom Nevo, Eran |
| Abstract | (MATH) A collection of simple closed Jordan curves in the plane is called a family of pseudo-circles if any two of its members intersect at most twice. A closed curve composed of two subarcs of distinct pseudo-circles is said to be an empty lens if it does not intersect any other member of the family. We establish a linear upper bound on the number of empty lenses in an arrangement of n pseudo-circles with the property that any two curves intersect precisely twice. Enhancing this bound in several ways, and combining it with the technique of Tamaki and Tokuyama [16], we show that any collection of n pseudo-circles can be cut into \$\bx\$ arcs so that any two intersect at most once, provided that the given pseudo-circles are x-monotone and admit an algebraic representation by three real parameters; here \$\alpha(n)\$ is the inverse Ackermann function, and s is a constant that depends on the algebraic degree of the representation of the pseudo-circles (s=2 for circles and parabolas). For arbitrary collections of pseudo-circles, any two of which intersect twice, the number of necessary cuts reduces to O(n $^{4/3}).$ As applications, we obtain improved bounds for the number of point-curve incidences, the complexity of a single level, and the complexity of many faces in arrangements of circles, pairwise intersecting pseudo-circles, parabolas, and families of homothetic copies of a fixed convex curve. We also obtain a variant of the Gallai-Sylvester theorem for arrangements of pairwise intersecting pseudo-circles, and a new lower bound for the number of distinct distances among n points in the plane under any simply-defined norm or convex distance function. |
| Starting Page | 123 |
| Ending Page | 132 |
| Page Count | 10 |
| File Format | |
| ISBN | 1581135041 |
| DOI | 10.1145/513400.513417 |
| Language | English |
| Publisher | Association for Computing Machinery (ACM) |
| Publisher Date | 2002-06-05 |
| Publisher Place | New York |
| Access Restriction | Subscribed |
| Subject Keyword | Pseudo-circles Arrangements Levels Incidences Distinct distances Lenses |
| Content Type | Text |
| Resource Type | Article |
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