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We prove the absence of a universal diameter bound on lengths of curves in a sweep-out of a Riemannian 2-sphere. If such bound existed it would yield a simple proof of existence of short geodesic segments and closed geodesics on a sphere of…

Differential Geometry · Mathematics 2011-06-01 Yevgeny Liokumovich

For many fundamental problems in computational topology, such as unknot recognition and $3$-sphere recognition, the existence of a polynomial-time solution remains unknown. A major algorithmic tool behind some of the best known algorithms…

Computational Geometry · Computer Science 2024-03-08 Benjamin A. Burton , Alexander He

The science of complexity is far from being fully understood and even its foundations are not well established. On the other hand, during the last decade, the random motion of particles or waves - the so-called diffusion - has been known…

Statistical Mechanics · Physics 2009-08-14 Guilherme R. Rezende , Luciano C. Lapas , Fernando A. Oliveira

We prove the non-existence of special generic maps on $3$-dimensional complex projective space as our new result and a corollary by several methods. Special generic maps are generalizations of Morse functions with exactly two singular…

Algebraic Topology · Mathematics 2023-12-19 Naoki Kitazawa

An arrangement of pseudocircles is a finite set of oriented closed Jordan curves each two of which cross each other in exactly two points. To describe the combinatorial structure of arrangements on closed orientable surfaces, in (Linhart,…

Combinatorics · Mathematics 2007-05-23 Ronald Ortner

This is a write-up of a lecture at the level of a physics colloquium. There exists an idealized mathematical formulation of strong interactions which has no free parameters but is known to describe the real world quite accurately. Over the…

High Energy Physics - Lattice · Physics 2010-05-20 Herbert Neuberger

We prove the existence of subspace designs with any given parameters, provided that the dimension of the underlying space is sufficiently large in terms of the other parameters of the design and satisfies the obvious necessary divisibility…

Combinatorics · Mathematics 2023-02-15 Peter Keevash , Ashwin Sah , Mehtaab Sawhney

There exist pairs of orthogonal Latin squares of any order n except if n=2 or n=6 [Bose, Shrikhande and Parker, 1960]. In particular, the problem of Euler's thirty-six officers does not have a solution. However, it has a "quantum solution":…

Quantum Physics · Physics 2026-03-04 Simeon Ball , Robin Simoens

I shall describe a general model-theoretic task to construct expansions of pseudofinite structures and discuss several examples of particular relevance to computational complexity. Then I will present one specific situation where finding a…

Logic · Mathematics 2017-02-10 Jan Krajicek

Understanding how particles are arranged on the sphere is not only central to numerous physical, biological, and materials systems but also finds applications in mathematics and in analysis of geophysical and meteorological measurements. In…

Soft Condensed Matter · Physics 2019-03-06 Anže Lošdorfer Božič , Simon Čopar

The space-like hypersurface of the Universe at the present cosmological time is a three-dimensional manifold. A non-trivial global topology of this space-like hypersurface would imply that the apparently observable universe (the sphere of…

Astrophysics · Physics 2011-04-15 Boudewijn F. Roukema , Vincent Blanloeil

This paper proves the existence of homeomorphic (diffeomorphic) complex 6-dimensional (7-dim) complete intersections that belong to components of the moduli space of different dimensions. These results are given as a supplement to earlier…

Algebraic Topology · Mathematics 2014-11-04 Jianbo Wang

Paper withdrawn by the author.

Differential Geometry · Mathematics 2007-08-14 Mikhail G. Katz

We provide an alternative, simpler proof of the existence of thick triangulations for noncompact $\mathcal{C}^1$ manifolds. Moreover, this proof is simpler than the original one given in \cite{pe}, since it mainly uses tools of elementary…

Geometric Topology · Mathematics 2010-05-12 Emil Saucan , Meir Katchalski

There exists a complex structure $J$ on a connected open subset $S^3_{\delta}\times S^3$ of $S^6$. The present paper proves that: (1) $J$ can be extended to a global almost complex structure $\widetilde{J}$ on $S^6$; (2) any extension to…

Complex Variables · Mathematics 2026-01-12 Zizhou Tang , Wenjiao Yan

Criterions for constancy of the holomorphic sectional curvature and the antiholomorphic sectional curvature are proved for almost Hermitian manifolds. It is shown, that an almost Hermitian manifold satisfying the axiom of antiholomorphic…

Differential Geometry · Mathematics 2010-04-22 Ognian Kassabov

By the Fox's re-embedding theorem, any compact submanifold of the 3-sphere can be re-embedded in the 3-sphere so that it is unknotted. It is unknown whether the Fox's re-embedding can be replaced with twistings. In this paper, we will show…

Geometric Topology · Mathematics 2019-02-07 Makoto Ozawa

Let X be a closed surface of genus two embedded in the 3-sphere. Then X inherits a metric and an orientation, which give an almost complex structure, which automatically integrates to a genuine complex structure, making X a Riemann surface.…

Complex Variables · Mathematics 2016-07-22 Neil Strickland

This essay presents a critical evaluation of the concepts of string theory and its impact on particle physics. The point of departure is a historical review of four decades of string theory within the broader context of six decades of…

Physics and Society · Physics 2015-06-26 Bert Schroer

Let M be a closed embedded minimal hypersurface in a Euclidean sphere of dimension n+1, we prove that it is strongly rigid. As applications we confirm the conjecture proposed by Choi and Schoen in [3] and the Chern conjecture for n less…

Differential Geometry · Mathematics 2023-12-06 Xu Han
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