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Let $ES_{d}(n)$ be the smallest integer such that any set of $ES_{d}(n)$ points in $\mathbb{R}^{d}$ in general position contains $n$ points in convex position. In 1960, Erd\H{o}s and Szekeres showed that $ES_{2}(n) \geq 2^{n-2} + 1$ holds,…

Combinatorics · Mathematics 2022-08-10 Cosmin Pohoata , Dmitrii Zakharov

We prove a lower bound on the number of the convex components of a compact set with non-empty interior in $\mathbb{R}^n$ for all $n\ge2$. Our result generalizes and improves the inequalities previously obtained in M. Carozza, F. Giannetti,…

Metric Geometry · Mathematics 2023-09-07 Flavia Giannetti , Giorgio Stefani

We show that there exist convex bodies of constant width in $\mathbb{E}^n$ with illumination number at least $(\cos(\pi/14)+o(1))^{-n}$, answering a question by G. Kalai. Furthermore, we prove the existence of finite sets of diameter $1$ in…

Metric Geometry · Mathematics 2024-06-27 Andrii Arman , Andriy Bondarenko , Andriy Prymak

We prove that there exist infinitely many coprime numbers $a$, $b$, $c$ with $a+b=c$ and $c>\operatorname{rad}(abc)\exp(6.563\sqrt{\log c}/\log\log c)$. These are the most extremal examples currently known in the $abc$ conjecture, thereby…

Number Theory · Mathematics 2024-06-05 Curtis Bright

An affine version of the linear subspace concentration inequality as proposed by Wu is established for centered convex bodies. This generalizes results from Wu and Freyer, Henk, Kipp on polytopes to convex bodies.

Metric Geometry · Mathematics 2024-09-24 Katharina Eller , Ansgar Freyer

In 1933, Borsuk conjectured that any bounded d-dimensional set of nonzero diameter can be broken into d + 1 parts of smaller diameter. This conjecture was disproved for large enough d, though it is true for low dimensional cases. The paper…

Metric Geometry · Mathematics 2010-10-12 Dian Yang

It is proved that the total length of any set of countably many rectifiable curves, whose union meets all straight lines that intersect the unit square U, is at least 2.00002. This is the first improvement on the lower bound of 2…

Computational Geometry · Computer Science 2014-04-11 Akitoshi Kawamura , Sonoko Moriyama , Yota Otachi , János Pach

In 1914 Lebesgue defined a "universal covering" to be a convex subset of the plane that contains an isometric copy of any subset of diameter 1. His challenge of finding a universal covering with the least possible area has been addressed by…

Metric Geometry · Mathematics 2017-08-22 John C. Baez , Karine Bagdasaryan , Philip Gibbs

We improve our earlier upper bound on the numbers of antipodal pairs of points among $n$ points in ${\mathbb{R}}^3$, to $2n^2/5+O(n^c)$, for some $c<2$. We prove that the minimal number of antipodal pairs among $n$ points in convex position…

Combinatorics · Mathematics 2021-06-03 E. Makai , H. Martini , M. H. Nguyên , V. Soltan , I. Talata

We study the volume ratio between projections of two convex bodies. Given a high-dimensional convex body $K$ we show that there is another convex body $L$ such that the volume ratio between any two projections of fixed rank of the bodies…

Metric Geometry · Mathematics 2022-11-14 Daniel Galicer , Alexander E. Litvak , Mariano Merzbacher , Damián Pinasco

We prove explicit bounds on the number of lattice points on or near a convex curve in terms of geometric invariants such as length, curvature, and affine arclength. In several of our results we obtain the best possible constants. Our…

Number Theory · Mathematics 2022-07-21 Ralph Howard , Ognian Trifonov

Ehrhart's conjecture proposes a sharp upper bound on the volume of a convex body whose barycenter is its only interior lattice point. Recently, Berman and Berndtsson proved this conjecture for a class of rational polytopes including…

Combinatorics · Mathematics 2013-02-19 Benjamin Nill , Andreas Paffenholz

We adapt an argument of Tao and Vu to show that if $\lambda_1\le\cdots\le\lambda_d$ are the successive minima of an origin-symmetric convex body $K$ with respect to some lattice $\Lambda<\mathbb{R}^d$, and if we set…

Metric Geometry · Mathematics 2024-10-02 Matthew Tointon

Makeev conjectured that every constant-width body is inscribed in the dual difference body of a regular simplex. We prove that homologically, there are an odd number of such circumscribing bodies in dimension 3, and therefore geometrically…

Metric Geometry · Mathematics 2007-05-23 Greg Kuperberg

Determining the minimum density of a covering of $\mathbb{R}^{n}$ by Euclidean unit balls as $n\to\infty$ is a major open problem, with the best known results being the lower bound of $\left(\mathrm{e}^{-3/2}+o(1)\right)n$ by Coxeter, Few…

Combinatorics · Mathematics 2025-10-30 Boris Bukh , Jun Gao , Xizhi Liu , Oleg Pikhurko , Shumin Sun

This thesis consists of five papers about reduced spherical convex bodies and in particular spherical bodies of constant width on the $d$-dimensional sphere $S^d$. In paper I we present some facts describing the shape of reduced bodies of…

Metric Geometry · Mathematics 2024-09-12 Michał Musielak

Let $A^2(D)$ be the Bergman space over the open unit disk $D$ in the complex plane. Korenblum conjectured that there is an absolute constant $c \in (0,1)$ such that whenever $|f(z)|\le |g(z)|$ in the annulus $c<|z|<1$ then $||f(z)|| \le…

Complex Variables · Mathematics 2015-05-13 Chun-Yen Shen

Clemm and Trebat-Leder (2014) proved that the number of quadratic number fields with absolute discriminant bounded by $x$ over which there exist elliptic curves with good reduction everywhere and rational $j$-invariant is $\gg…

Number Theory · Mathematics 2023-02-15 Benjamin Matschke , Abhijit S. Mudigonda

We define a class of $L$-convex-concave subsets of $\mathbb{R}P^3$, where $L$ is a projective line in $\mathbb{R}P^3$. These are sets whose sections by any plane containing $L$ are convex and concavely depend on this plane. We prove a…

Differential Geometry · Mathematics 2007-05-23 A. Khovanskii , D. Novikov

For natural numbers $n$ and $l > d \geq 2$, let $ES_d(l,n)$ be the minimum $N$ such that any set of at least $N$ points in $\mathbb{R}^d$ contains either $l$ points contained in a common $(d-1)$-dimensional hyperplane or $n$ points in…

Combinatorics · Mathematics 2025-06-02 Koki Furukawa
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