Abstract
We consider sets L={ℓ 1,…,ℓ n} of n labeled lines in general position in R 3, and study the order types of point sets {p 1,…,p n} that stem from the intersections of the lines in L with (directed) planes Π not parallel to any line of L, that is, the proper cross-sections of L. As two main results, we show that the number of different order types that can be obtained as cross-sections of L is O(n 9) when considering all possible planes Π and O(n 3) when restricting considerations to sets of pairwise parallel planes, where both bounds are tight. The result for parallel planes implies that any set of n points in R 2 moving with constant (but possibly different) speeds along straight lines forms at most O(n 3) different order types over time. We further generalize the setting from R 3 to R d with d>3, showing that the number of order types that can be obtained as cross-sections of a set of n labeled (d−2)-flats in R d with planes is O(((n3)+nd(d−2))).
Original language | English |
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Pages (from-to) | 51-61 |
Number of pages | 11 |
Journal | Computational Geometry |
Volume | 77 |
DOIs | |
Publication status | Published - 2019 |
Keywords
- Cross-section
- Lines in 3-space
- Moving points in the plane
- Order type
ASJC Scopus subject areas
- Computational Mathematics
- Control and Optimization
- Geometry and Topology
- Computer Science Applications
- Computational Theory and Mathematics