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We prove that the single-source shortest-path problem on disk graphs can be solved in $O(n\log n)$ time, and that it can be solved on intersection graphs of fat triangles in $O(n\log^2 n)$ time.

Computational Geometry · Computer Science 2025-06-10 Mark de Berg , Sergio Cabello

We construct a set of points with $\Omega(n^2\log n)$ triples determining an angle $\theta$ whenever $\tan(\theta)$ is algebraic over $\mathbb{Q}$, matching the upper bound of Pach and Sharir. This improves upon the original construction,…

Combinatorics · Mathematics 2022-01-27 Max Aires

We investigate the problem of partitioning a rectilinear polygon $P$ with $n$ vertices and no holes % with no holes into rectangles using disjoint line segments drawn inside $P$ under two optimality criteria. In the minimum ink partition,…

Computational Geometry · Computer Science 2021-11-04 Hwi Kim , Jaegun Lee , Hee-Kap Ahn

We present time-space trade-offs for computing the Euclidean minimum spanning tree of a set $S$ of $n$ point-sites in the plane. More precisely, we assume that $S$ resides in a random-access memory that can only be read. The edges of the…

Computational Geometry · Computer Science 2021-02-03 Bahareh Banyassady , Luis Barba , Wolfgang Mulzer

A polygon is \textit{small} if it has unit diameter. The maximal area of a small polygon with a fixed number of sides $n$ is not known when $n$ is even and $n\geq14$. We determine an improved lower bound for the maximal area of a small…

Metric Geometry · Mathematics 2022-04-12 Christian Bingane , Michael J. Mossinghoff

We give a simplified and improved lower bound for the simplex range reporting problem. We show that given a set $P$ of $n$ points in $\mathbb{R}^d$, any data structure that uses $S(n)$ space to answer such queries must have…

Computational Geometry · Computer Science 2022-10-27 Peyman Afshani , Pingan Cheng

Given a planar undirected n-vertex graph G with non-negative edge weights, we show how to compute, for given vertices s and t in G, a min st-cut in G in O(n loglog n) time and O(n) space. The previous best time bound was O(n log n).

Discrete Mathematics · Computer Science 2010-10-08 Christian Wulff-Nilsen

If a (cusped) surface S admits an ideal triangulation T with no shears, we show an efficient algorithm to give S as a quotient of hypebolic plane by a subgroup of PSL(2, Z). The algorithm runs in time O(n log n), where n is the number of…

Geometric Topology · Mathematics 2007-05-23 Igor Rivin

Let $ \Omega \subsetneq \mathbf{R}^n\,(n\geq 2)$ be an unbounded convex domain. We study the minimal surface equation in $\Omega$ with boundary value given by the sum of a linear function and a bounded uniformly continuous function in $…

Analysis of PDEs · Mathematics 2022-01-19 Guosheng Jiang , Zhehui Wang , Jintian Zhu

We study the Euclidean minimum weight perfect matching problem for $n$ points in the plane. It is known that any deterministic approximation algorithm whose approximation ratio depends only on $n$ requires at least $\Omega(n \log n)$ time.…

Computational Geometry · Computer Science 2026-01-09 Stefan Hougardy , Karolina Tammemaa

Methodology is provided towards the solution of the minimum enclosing ball problem. This problem concerns the determination of the unique spherical surface of smallest radius enclosing a given bounded set in the d-dimensional Euclidean…

Computational Geometry · Computer Science 2024-10-16 Michael N. Vrahatis

A small polygon is a polygon of unit diameter. The maximal area of a small polygon with $n=2m$ vertices is not known when $m \ge 7$. In this paper, we construct, for each $n=2m$ and $m\ge 3$, a small $n$-gon whose area is the maximal value…

Combinatorics · Mathematics 2023-06-21 Christian Bingane

In this paper we present new data structures for two extensively studied variants of the orthogonal range searching problem. First, we describe a data structure that supports two-dimensional orthogonal range minima queries in $O(n)$ space…

Data Structures and Algorithms · Computer Science 2020-07-23 Yakov Nekrich

We consider a problem in computational origami. Given a piece of paper as a convex polygon $P$ and a point $f$ located within, fold every point on a boundary of $P$ to $f$ and compute a region that is safe from folding, i.e., the region…

Computational Geometry · Computer Science 2023-05-03 Nattawut Phetmak , Jittat Fakcharoenphol

Let $\mathcal{P}$ be the surface of a convex polyhedron with $n$ vertices. We consider the two-point shortest path query problem for $\mathcal{P}$: Constructing a data structure so that given any two query points $s$ and $t$ on…

Computational Geometry · Computer Science 2025-12-15 Haitao Wang

We give near-tight lower bounds for the sparsity required in several dimensionality reducing linear maps. First, consider the JL lemma which states that for any set of n vectors in R there is a matrix A in R^{m x d} with m = O(eps^{-2}log…

Data Structures and Algorithms · Computer Science 2012-11-07 Jelani Nelson , Huy L. Nguyen

The threshold degree of a function f:{0,1}^n->{-1,+1} is the least degree of a real polynomial p with f(x)=sgn p(x). We prove that the intersection of two halfspaces on {0,1}^n has threshold degree Omega(n), which matches the trivial upper…

Computational Complexity · Computer Science 2010-02-25 Alexander A. Sherstov

In this paper, we establish two necessary conditions for a joint triangulation of two sets of $n$ points in the plane and conjecture that they are sufficient. We show that these necessary conditions can be tested in $O(n^3)$ time. For the…

Discrete Mathematics · Computer Science 2011-02-08 Ajit Arvind Diwan , Subir Kumar Ghosh , Partha Pratim Goswami , Andrzej Lingas

We consider the problem of minimising the number of edges that are contained in triangles, among $n$-vertex graphs with a given number of edges. We prove a conjecture of F\"uredi and Maleki that gives an exact formula for this minimum, for…

Combinatorics · Mathematics 2016-05-03 Vytautas Gruslys , Shoham Letzter

The problem of finding a local minimum of a black-box function is central for understanding local search as well as quantum adiabatic algorithms. For functions on the Boolean hypercube {0,1}^n, we show a lower bound of Omega(2^{n/4}/n) on…

Quantum Physics · Physics 2007-05-23 Scott Aaronson