,
Chaeyoon Chung,
Jean-Lou De Carufel
,
John Iacono
,
Anil Maheshwari
,
Saeed Odak,
Michiel Smid,
Csaba D. Tóth
Creative Commons Attribution 4.0 International license
Let S be a set of n points in ℝ^d, where d ≥ 2 is a constant, and let H₁,H₂,…,H_{m+1} be a sequence of vertical hyperplanes that are sorted by their first coordinates, such that exactly n/m points of S are between any two successive hyperplanes. Let |A(S,m)| be the number of different closest pairs in the {(m+1) choose 2} vertical slabs that are bounded by H_i and H_j, over all 1 ≤ i < j ≤ m+1. We prove tight bounds for the largest possible value of |A(S,m)|, over all point sets of size n, and for all values of 1 ≤ m ≤ n.
As a result of these bounds, we obtain, for any constant ε > 0, a data structure of size O(n), such that for any vertical query slab Q, the closest pair in the set Q ∩ S can be reported in O(n^{1/2+ε}) time. Prior to this work, no linear space data structure with sublinear query time was known.
@InProceedings{biniaz_et_al:LIPIcs.WADS.2025.8,
author = {Biniaz, Ahmad and Bose, Prosenjit and Chung, Chaeyoon and De Carufel, Jean-Lou and Iacono, John and Maheshwari, Anil and Odak, Saeed and Smid, Michiel and T\'{o}th, Csaba D.},
title = {{Tight Bounds on the Number of Closest Pairs in Vertical Slabs}},
booktitle = {19th International Symposium on Algorithms and Data Structures (WADS 2025)},
pages = {8:1--8:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-398-0},
ISSN = {1868-8969},
year = {2025},
volume = {349},
editor = {Morin, Pat and Oh, Eunjin},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WADS.2025.8},
URN = {urn:nbn:de:0030-drops-242391},
doi = {10.4230/LIPIcs.WADS.2025.8},
annote = {Keywords: closest pair, vertical slab, data structure}
}