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In this paper we prove that a smooth embedded paper Moebius band must have aspect ratio greater than $\sqrt 3$. We also prove that any sequence of smooth embedded paper Moebius bands whose aspect ratio converges to $\sqrt 3$ must converge,…

Metric Geometry · Mathematics 2024-10-15 Richard Evan Schwartz

Let $A=\sqrt 3$. There are two main conjectures about paper Moebius bands. First, a smooth embedded paper Moebius band must have aspect ratio at least A. Second, any sequence of smooth embedded paper Moebius bands having aspect ratio…

Metric Geometry · Mathematics 2023-09-12 Richard Evan Schwartz

Let $\epsilon<1/384$ and let $\Omega$ be a smooth embedded paper Moebius band of aspect ratio less than $\sqrt 3 + \epsilon$. We prove that $\Omega$ is within Hausdorff distance $18 \sqrt \epsilon$ of an equilateral triangle of perimeter $2…

Metric Geometry · Mathematics 2024-12-03 Richard Evan Schwartz

We introduce the crisscross and the cup, both of which are immersed $3$-twist polygonal paper Moebius band of aspect ratio $3$. We explain why these two objects are limits of smooth embedded paper Moebius bands having knotted boundary. We…

Metric Geometry · Mathematics 2023-10-17 Brienne Elisabeth Brown , Richard Evan Schwartz

This paper presents a construction of a folded paper ribbon knot that provides a constant upper bound on the infimal aspect ratio for paper M\"obius bands and annuli with arbitrarily many half-twists. In particular, the construction shows…

Geometric Topology · Mathematics 2024-04-16 Aidan Hennessey

We prove that every knot in the 3-space bounds an embedded punctured Moebius band whose other boundary component is a quasipositive fibred knot.

Geometric Topology · Mathematics 2007-05-23 Sebastian Baader

This paper gives another proof of the key lemma in my recent paper which solves the optimal paper Moebius band conjecture of Halpern and Weaver, namely Lemma T. The proof here is longer but it offers more geometric intuition about what is…

Metric Geometry · Mathematics 2024-04-24 Richard Evan Schwartz

In 1974, Witsenhausen asked for the maximum possible density $\alpha_n$ of a measurable subset $A$ of the unit sphere $\mathbb{S}^{n-1}\subset \mathbb{R}^n$ such that $A$ contains no pair of orthogonal vectors. For $n=3$, the best known…

Combinatorics · Mathematics 2026-05-28 Domonkos Czifra , Ákos Dúcz , Máté Matolcsi , Dániel Varga , Pál Zsámboki

We establish an improved upper bound for the number of incidences between m points and n circles in three dimensions. The previous best known bound, originally established for the planar case and later extended to any dimension $\ge 2$, is…

Combinatorics · Mathematics 2019-02-20 Micha Sharir , Adam Sheffer , Joshua Zahl

This paper is devoted to the spatial analyticity of the solution of the BBM equation on the real line with an analytic initial data. It is shown that the analytic radius has a lower bound like $t^{-\frac{2}{3}}$ as time $t$ goes to…

Analysis of PDEs · Mathematics 2022-08-02 Ming Wang

We introduce an arbitrary order, computationally efficient method to smooth corners on curves in the plane, as well as edges and vertices on surfaces in $\mathbb R^3$. The method is local, only modifying the original surface in a…

Numerical Analysis · Mathematics 2016-04-08 Charles L. Epstein , Michael O'Neil

We give an improved lower bound of 10/3 on the competitive ratio for the exploration of an undirected, edge-weighted graph with a single agent that needs to return to the starting location after visiting all vertices. We assume that the…

Data Structures and Algorithms · Computer Science 2020-02-26 Alexander Birx , Yann Disser , Alexander V. Hopp , Christina Karousatou

We prove that the expected area of the amoeba of a complex plane curve of degree $d$ is less than $\displaystyle{3\ln(d)^2/2+9\ln(d)+9}$ and once rescaled by $\ln(d)^2$, is asymptotically bounded from below by $3/4$. In order to get this…

Algebraic Geometry · Mathematics 2024-03-04 Ali Ulaş Özgür Kişisel , Jean-Yves Welschinger

This work presents a geometric refinement of the classical Cram\'er--Rao bound (CRB) in the non-asymptotic regime by incorporating curvature-aware corrections based on the second fundamental form associated with the statistical model…

Statistics Theory · Mathematics 2026-03-11 Sunder Ram Krishnan

We characterize the standard $\mathbb{S}^3$ as the closed Ricci-positive 3-manifold with scalar curvature at least 6 having isoperimetric surfaces of largest area: $4\pi$. As a corollary we answer in the affirmative an interesting special…

Differential Geometry · Mathematics 2009-06-08 Michael Eichmair

By definition, a rigid graph in $\mathbb{R}^d$ (or on a sphere) has a finite number of embeddings up to rigid motions for a given set of edge length constraints. These embeddings are related to the real solutions of an algebraic system.…

Combinatorics · Mathematics 2021-10-26 Evangelos Bartzos , Ioannis Z. Emiris , Raimundas Vidunas

We provide new upper and lower bounds on the minimum possible ratio of the spectral and Frobenius norms of a (partially) symmetric tensor. In the particular case of general tensors our result recovers a known upper bound. For symmetric…

Functional Analysis · Mathematics 2024-03-05 Khazhgali Kozhasov , Josué Tonelli-Cueto

We prove that the Almgren-Pitts 6-width of the unit 3-ball is less than $2\pi$. We also prove that there exists a free boundary minimal surface in the unit 3-ball that has genus at most 1, index at most 5, area less than $2\pi$, and is not…

Differential Geometry · Mathematics 2023-05-17 Adrian Chun-Pong Chu

In this paper, we give an affirmative answer to Gromov's conjecture ([3, Conjecture E]) by establishing an optimal Lipschitz lower bound for a class of smooth functions on orientable open $3$-manifolds with uniformly positive sectional…

Differential Geometry · Mathematics 2020-07-28 Jintian Zhu

It is known that the surface of a cone over the unit disc with large height has smaller distortion than the standard embedding of the 2-sphere in $\mathbb R^3$. In this note we show that distortion minimisers exist among convex embedded…

Metric Geometry · Mathematics 2019-04-17 Sebastian Baader , Luca Studer , Roger Züst
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