Finding triangles and other small subgraphs in geometric intersection graphs

TM Chan - Proceedings of the 2023 Annual ACM-SIAM …, 2023 - SIAM
We consider problems related to finding short cycles, small cliques, small independent sets,
and small subgraphs in geometric intersection graphs. We obtain a plethora of new results …

Semi-algebraic off-line range searching and biclique partitions in the plane

PK Agarwal, E Ezra, M Sharir - arXiv preprint arXiv:2403.12276, 2024 - arxiv.org
Let $ P $ be a set of $ m $ points in ${\mathbb R}^ 2$, let $\Sigma $ be a set of $ n $ semi-
algebraic sets of constant complexity in ${\mathbb R}^ 2$, let $(S,+) $ be a semigroup, and …

On ray shooting for triangles in 3-space and related problems

E Ezra, M Sharir - SIAM Journal on Computing, 2022 - SIAM
We consider several intersection searching problems that involve lines in \mathbbR^3 and
present improved algorithms for solving them. The problems include (i) ray shooting amid …

Semialgebraic range stabbing, ray shooting, and intersection counting in the plane

TM Chan, P Cheng, DW Zheng - arXiv preprint arXiv:2403.12303, 2024 - arxiv.org
Polynomial partitioning techniques have recently led to improved geometric data structures
for a variety of fundamental problems related to semialgebraic range searching and …

Lower bounds for intersection reporting among flat objects

P Afshani, P Cheng - arXiv preprint arXiv:2302.11433, 2023 - arxiv.org
Recently, Ezra and Sharir [ES22a] showed an $ O (n^{3/2+\sigma}) $ space and $ O
(n^{1/2+\sigma}) $ query time data structure for ray shooting among triangles in $\mathbb …

On reverse shortest paths in geometric proximity graphs

PK Agarwal, MJ Katz, M Sharir - Computational Geometry, 2024 - Elsevier
Let S be a set of n geometric objects of constant complexity (eg, points, line segments, disks,
ellipses) in R 2, and let ϱ: S× S→ R≥ 0 be a distance function on S. For a parameter r≥ 0 …

Vertical Decomposition in 3D and 4D with Applications to Line Nearest-Neighbor Searching in 3D

P K. Agarwal, E Ezra, M Sharir - Proceedings of the 2024 Annual ACM-SIAM …, 2024 - SIAM
Vertical decomposition is a widely used general technique for decomposing the cells of
arrangements of semi-algebraic sets in ℝd into constant-complexity subcells. In this paper …

Improved algebraic degeneracy testing

J Cardinal, M Sharir - Discrete & Computational Geometry, 2024 - Springer
In the classical linear degeneracy testing problem, we are given n real numbers and ak-
variate linear polynomial F, for some constant k, and have to determine whether there exist k …

Intersection searching amid tetrahedra in four dimensions

E Ezra, M Sharir - Discrete & Computational Geometry, 2024 - Springer
We develop data structures for intersection queries in four dimensions that involve
segments, triangles and tetrahedra. Specifically, we study three main problems:(i) …

Discrete Fr\'echet Distance Oracles

B Aronov, T Farhana, MJ Katz, I Ramesh - arXiv preprint arXiv:2404.04065, 2024 - arxiv.org
It is unlikely that the discrete Fr\'echet distance between two curves of length $ n $ can be
computed in strictly subquadratic time. We thus consider the setting where one of the curves …