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Redondo Beach, California

Nov. 12, 2000 to Nov. 14, 2000

ISBN: 0-7695-0850-2

pp: 423

J. Pach , City Coll., CUNY, NY, USA

ABSTRACT

A triangle is said to be /spl delta/-fat if its smallest angle is at least /spl delta/<0. A connected component of the complement of the union of a family of triangles is called hole. It is shown that any family of /spl delta/-far triangles in the plane determines at most O (n//spl delta/ log 2//spl delta/) holes. This improves on some earlier bounds of (Efrat et al., 1993; Matousek et al., 1994). Solving a problem of (Agarwal and Bern, 1999) we also give a general upper bound for the number of holes determined by n triangles in the plane with given angles. As a corollary, we obtain improved upper bounds for the boundary complexity of the union of fat polygons in the plane, which, in turn, leads to better upper bounds for the running times of some known algorithms for motion planning, for finding a separator line for a set of segments, etc.

INDEX TERMS

computational complexity; computational geometry; boundary complexity; fat triangle union; holes; upper bounds; motion planning; separator line; computational geometry

CITATION

J. Pach,
"On the boundary complexity of the union of fat triangles",

*FOCS*, 2000, 2013 IEEE 54th Annual Symposium on Foundations of Computer Science, 2013 IEEE 54th Annual Symposium on Foundations of Computer Science 2000, pp. 423, doi:10.1109/SFCS.2000.892130