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We study the question of how to compute a point in the convex hull of an input set $S$ of $n$ points in ${\mathbb R}^d$ in a differentially private manner. This question, which is trivial non-privately, turns out to be quite deep when…

Data Structures and Algorithms · Computer Science 2020-03-31 Haim Kaplan , Micha Sharir , Uri Stemmer

Recently classes of conic and discrete conic functions were introduced. In this paper we use the term convic instead conic. The class of convic functions properly includes the classes of convex functions, strictly quasiconvex functions and…

Optimization and Control · Mathematics 2020-11-03 S. I. Veselov , D. V. Gribanov , N. Yu. Zolotykh , A. Yu. Chirkov

$\newcommand{\Arr}{\mathcal{A}} \newcommand{\numS}{k} \newcommand{\ArrX}[1]{\Arr(#1)} \newcommand{\eps}{\varepsilon} \newcommand{\opt}{\mathsf{o}}$ For point sets $P_1, \ldots, P_\numS$, a set of lines $L$ is halving if any face of the…

Computational Geometry · Computer Science 2022-08-25 Sariel Har-Peled , Da Wei Zheng

Seeking the convex hull of an object is a very fundamental problem arising from various tasks. In this work, we propose two variational convex hull models using level set representation for 2-dimensional data. The first one is an exact…

Computer Vision and Pattern Recognition · Computer Science 2019-08-12 Lingfeng Li , Shousheng Luo , Xue-Cheng Tai , Jiang Yang

Given a set $P$ of $n$ points in the plane, its unit-disk graph $G(P)$ is a graph with $P$ as its vertex set such that two points of $P$ are connected by an edge if their (Euclidean) distance is at most $1$. We consider several classical…

Computational Geometry · Computer Science 2025-01-03 Anastasiia Tkachenko , Haitao Wang

In this paper, we address the problem of minimizing a convex function f over a convex set, with the extra constraint that some variables must be integer. This problem, even when f is a piecewise linear function, is NP-hard. We study an…

Optimization and Control · Mathematics 2012-09-05 Michel Baes , Timm Oertel , Christian Wagner , Robert Weismantel

This paper proposed a method to judge whether the point is inside or outside of the simple convex polygon by the intersection of the vertical line. It determined the point to an area enclosed by two straight lines, then convert the problem…

Computational Geometry · Computer Science 2022-06-07 Sun Yixuan , Zhu Zhehao

Let $P$ be a set of $n$ points in $\mathbb{R}^2$. For a given positive integer $w<n$, our objective is to find a set $C \subset P$ of points, such that $CH(P\setminus C)$ has the smallest number of vertices and $C$ has at most $n-w$ points.…

Computational Geometry · Computer Science 2021-03-03 Vahideh Keikha

Let P be a set of n points in R^3. The 2-center problem for P is to find two congruent balls of minimum radius whose union covers P. We present two randomized algorithms for computing a 2-center of P. The first algorithm runs in O(n^3 log^5…

Computational Geometry · Computer Science 2010-12-14 Pankaj K. Agarwal , Rinat Ben Avraham , Micha Sharir

In this article, we determine the amortized computational complexity of the planar dynamic convex hull problem by querying. We present a data structure that maintains a set of n points in the plane under the insertion and deletion of points…

Computational Geometry · Computer Science 2019-03-01 Riko Jacob , Gerth Stølting Brodal

Interesting theoretical associations have been established by recent papers between the fields of active learning and stochastic convex optimization due to the common role of feedback in sequential querying mechanisms. In this paper, we…

Machine Learning · Computer Science 2015-05-19 Aaditya Ramdas , Aarti Singh

We consider the planar Euclidean two-center problem in which given $n$ points in the plane we are to find two congruent disks of the smallest radius covering the points. We present a deterministic $O(n \log n)$-time algorithm for the case…

Computational Geometry · Computer Science 2020-07-09 Jongmin Choi , Hee-Kap Ahn

While recent work suggests that quantum computers can speed up the solution of semidefinite programs, little is known about the quantum complexity of more general convex optimization. We present a quantum algorithm that can optimize a…

Quantum Physics · Physics 2020-01-15 Shouvanik Chakrabarti , Andrew M. Childs , Tongyang Li , Xiaodi Wu

Let $\mathcal{P}$ be a set of $h$ pairwise-disjoint polygonal obstacles with a total of $n$ vertices in the plane. We consider the problem of building a data structure that can quickly compute an $L_1$ shortest obstacle-avoiding path…

Computational Geometry · Computer Science 2014-03-17 Danny Z. Chen , Rajasekhar Inkulu , Haitao Wang

We give an overview of the 2020 Computational Geometry Challenge, which targeted the problem of partitioning the convex hull of a given planar point set P into the smallest number of convex faces, such that no point of P is contained in the…

Computational Geometry · Computer Science 2020-04-10 Erik D. Demaine , Sándor P. Fekete , Phillip Keldenich , Dominik Krupke , Joseph S. B. Mitchell

We consider the planar two-center problem for a convex polygon: given a convex polygon in the plane, find two congruent disks of minimum radius whose union contains the polygon. We present an $O(n\log n)$-time algorithm for the two-center…

Computational Geometry · Computer Science 2021-05-14 Jongmin Choi , Dahye Jeong , Hee-Kap Ahn

We consider a range-search variant of the closest-pair problem. Let $\varGamma$ be a fixed shape in the plane. We are interested in storing a given set of $n$ points in the plane in some data structure such that for any specified translate…

Computational Geometry · Computer Science 2019-03-25 Jie Xue , Yuan Li , Saladi Rahul , Ravi Janardan

We improve upon the running time for finding a point in a convex set given a separation oracle. In particular, given a separation oracle for a convex set $K\subset \mathbb{R}^n$ contained in a box of radius $R$, we show how to either find a…

Data Structures and Algorithms · Computer Science 2015-11-06 Yin Tat Lee , Aaron Sidford , Sam Chiu-wai Wong

Let $H_n$ be the minimal number of smaller homothetic copies of an $n$-dimensional convex body required to cover the whole body. Equivalently, $H_n$ can be defined via illumination of the boundary of a convex body by external light sources.…

Metric Geometry · Mathematics 2020-10-01 A. Prymak , V. Shepelska

We present a novel 2D convex hull peeling algorithm for outlier detection, which repeatedly removes the point on the hull that decreases the hull's area the most. To find k outliers among n points, one simply peels k points. The algorithm…

Computational Geometry · Computer Science 2025-09-29 Vinesh Sridhar , Rolf Svenning