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The simplicial depth, like other relevant multivariate statistical data depth functions, vanishes right outside the convex hull of the support of the distribution with respect to which the depth is computed. This is problematic when it is…

Statistics Theory · Mathematics 2024-01-15 Giacomo Francisci , Alicia Nieto-Reyes , Claudio Agostinelli

We prove the existence of an algorithm $A$ for computing 2-d or 3-d convex hulls that is optimal for every point set in the following sense: for every sequence $\sigma$ of $n$ points and for every algorithm $A'$ in a certain class…

Computational Geometry · Computer Science 2015-05-04 Peyman Afshani , Jérémy Barbay , Timothy Chan

This paper systematically investigates the geometry of fundamental quantum cones, the separable cone ($\mathscr{P}_+$) and the Positive Partial Transpose (PPT) cone ($\mathcal{P}_{\mathrm{PPT}}$), under generalized non-commutative…

Mathematical Physics · Physics 2025-12-11 Mohsen Kian

A convex partition of a point set P in the plane is a planar partition of the convex hull of P with empty convex polygons or internal faces whose extreme points belong to P. In a convex partition, the union of the internal faces give the…

Computational Geometry · Computer Science 2020-12-16 Hadrien Cambazard , Nicolas Catusse

Let $S$ be a set of $n$ points in 3-dimensional space. A tetrahedralization $\mathcal{T}$ of $S$ is a set of interior disjoint tetrahedra with vertices on $S$, not containing points of $S$ in their interior, and such that their union is the…

Computational Geometry · Computer Science 2012-10-22 Francisco Escalona , Ruy Fabila-Monroy , Jorge Urrutia

A matrix convex set is a set of the form $\mathcal{S} = \cup_{n\geq 1}\mathcal{S}_n$ (where each $\mathcal{S}_n$ is a set of $d$-tuples of $n \times n$ matrices) that is invariant under UCP maps from $M_n$ to $M_k$ and under formation of…

Operator Algebras · Mathematics 2025-04-15 Kenneth R. Davidson , Adam Dor-On , Orr Shalit , Baruch Solel

Let $S_k$ be a random walk in $R^d$ such that its distribution of increments does not assign mass to hyperplanes. We study the probability $p_n$ that the convex hull $conv (S_1, \ldots , S_n)$ of the first $n$ steps of the walk does not…

Probability · Mathematics 2017-08-02 Vladislav Vysotsky , Dmitry Zaporozhets

Any stretching of Ringel's non-Pappus pseudoline arrangement when projected into the Euclidean plane, implicitly contains a particular arrangement of nine triangles. This arrangement has a complex constraint involving the sines of its…

Combinatorics · Mathematics 2007-05-23 Jeremy J. Carroll

We consider ensembles of planar maps with two marked vertices at distance k from each other and look at the closed line separating these vertices and lying at distance d from the first one (d<k). This line divides the map into two…

Combinatorics · Mathematics 2017-11-20 Emmanuel Guitter

Let $P$ be a set of $n$ points in $\mathbb{R}^3$ in general position, and let $RCH(P)$ be the rectilinear convex hull of $P$. In this paper we obtain an optimal $O(n\log n)$-time and $O(n)$-space algorithm to compute $RCH(P)$. We also…

Computational Geometry · Computer Science 2022-09-14 Pablo Pérez-Lantero , Carlos Seara , Jorge Urrutia

We study Poncelet's Theorem in finite projective coordinate planes over the field $GF(p)$ and concentrate on a particular pencil of conics. For pairs of such conics we investigate whether we can find polygons with $n$ sides, which are…

Combinatorics · Mathematics 2014-09-11 Norbert Hungerbühler , Katharina Kusejko

We prove discrete Helly-type theorems for pseudohalfplanes, which extend recent results of Jensen, Joshi and Ray about halfplanes. Among others we show that given a family of pseudohalfplanes $\cal H$ and a set of points $P$, if every…

Combinatorics · Mathematics 2021-10-05 Balázs Keszegh

We prove that SVP$_p$ is NP-hard to approximate within a factor of $2^{\log^{1 - \varepsilon} n}$, for all constants $\varepsilon > 0$ and $p > 2$, under standard deterministic Karp reductions. This result is also the first proof that…

Computational Complexity · Computer Science 2026-03-31 Isaac M. Hair , Amit Sahai

Given a convex set $\Omega$ of $\mathbb{R}^n$, we consider the shape optimization problem of finding a convex subset $\omega\subset \Omega$, of a given measure, minimizing the $p$-distance functional $$\mathcal{J}_p(\omega) :=…

Optimization and Control · Mathematics 2025-01-03 Zakaria Fattah , Ilias Ftouhi , Enrique Zuazua

In this article we study the structured distance to singularity for a nonsingular matrix $A\in\mathbb{C}^{n\times n}$, with a prescribed linear structure $\mathcal{S}$ (for instance, a sparsity pattern, or a real Toeplitz structure), i.e.,…

Numerical Analysis · Mathematics 2026-03-06 Miryam Gnazzo , Nicola Guglielmi , Federico Poloni , Stefano Sicilia

The Continuous p-Dispersion Problem (CpDP) with boundary constraints asks for the placement of a fixed number of points in a compact subset of Euclidean space such that the minimum distance between any two points, as well as the points and…

Optimization and Control · Mathematics 2026-03-02 Sanjay Manoj , Melkior Ornik

Various real-world problems consist of partitioning a set of locations into disjoint subsets, each subset spread in a way that it covers the whole set with a certain radius. Given a finite set S, a metric d, and a radius r, define a subset…

Data Structures and Algorithms · Computer Science 2023-02-08 Eran Rosenbluth

Let T be the unit circle in the complex plane C. This paper proves the existence of analytic structure in a compact subset K of T X C^n, where K has so-called "lineally convex" or "hypoconvex" fibers over T. It also addresses a related…

Complex Variables · Mathematics 2007-05-23 Marshall A. Whittlesey

This paper proposes a new theoretical perspective for studying the Hodge conjecture through an analytical framework based on constraint geometry. Our theory begins with a key observation: in compatible pair Spencer theory, a "differential…

General Mathematics · Mathematics 2025-08-12 Dongzhe Zheng

Let $G$ be a graph and $S \subseteq V(G)$. In the cycle convexity, we say that $S$ is \textit{cycle convex} if for any $u\in V(G)\setminus S$, the induced subgraph of $S\cup\{u\}$ contains no cycle that includes $u$. The \textit{cycle…

Combinatorics · Mathematics 2024-12-30 Bijo S. Anand , Ullas Chandran S. V. , Julliano R. Nascimento , Revathy S. Nair