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We prove a lower bound on the length of closed geodesics for spheres with Willmore energy below $6\pi$. The energy threshold is optimal and the inequality cannot be extended to surfaces of higher genus. Moreover, we discuss consequences for…

Differential Geometry · Mathematics 2026-02-16 Marius Müller , Fabian Rupp , Christian Scharrer

In this work we are focused on the existence of Morse functions on a closed manifold $M$ which are far from being ordered, i.e. whose Reeb graphs have positive first Betti number, especially the maximal possible, equals…

Geometric Topology · Mathematics 2024-03-05 Łukasz Patryk Michalak

A compact polyhedron $X$ is said to have the Bounded Index Property for Homotopy Equivalence (BIPHE) if there is a finite bound $\mathcal{B}$ such that for any homotopy equivalence $f:X\rightarrow X$ and any fixed point class $\mathbf{F}$…

Geometric Topology · Mathematics 2019-09-04 Shengkui Ye , Qiang Zhang

An oriented compact closed manifold is called inflexible if the set of mapping degrees ranging over all continuous self-maps is finite. Inflexible manifolds have become of importance in the theory of functorial semi-norms on homology.…

Algebraic Topology · Mathematics 2011-09-06 Manuel Amann

We show that a noncompact manifold with bounded sectional curvature, whose ends are sufficiently Gromov-Hausdorff close to rays, has a finite dimensional space of square-integrable harmonic forms. In the special case of a finite-volume…

Differential Geometry · Mathematics 2007-05-23 John Lott

We construct, for $m\geq 6$ and $2n\leq m$, closed manifolds $M^{m}$ with finite nonzero $\varphi(M^{m},S^{n}$), where $\varphi(M,N)$ denotes the minimum number of critical points of a smooth map $M\to N$. We also give some explicit…

Geometric Topology · Mathematics 2019-01-25 Louis Funar , Cornel Pintea

In this article we construct closed, isospectral, non-isometric locally symmetric manifolds. We have three main results. First, we construct arbitrarily large sets of closed, isospectral, non-isometric manifolds. Second, we show the growth…

Differential Geometry · Mathematics 2016-11-16 D. B. McReynolds

If the n-dimensional unit sphere is covered by finitely many spherically convex bodies, then the sum of the inradii of these bodies is at least {\pi}. This bound is sharp, and the equality case is characterized.

Metric Geometry · Mathematics 2011-10-20 Karoly Bezdek , Rolf Schneider

In this paper we prove that the Morse boundary of a free product depends only on the Morse boundary of its factors. In fact, we also prove the analogous result for graphs of groups with finite edge groups and infinitely many ends. This is a…

Group Theory · Mathematics 2023-07-06 Stefanie Zbinden

We describe the topological structure of closed manifolds of dimension no less than four which admit Morse-Smale diffeomorphisms such that its non-wandering set contains any number of sink periodic points, and any number of source periodic…

Dynamical Systems · Mathematics 2020-03-18 V. Medvedev , E. Zhuzhoma

We consider the invariant measure of homogeneous random walks in the quarter-plane. In particular, we consider measures that can be expressed as an infinite sum of geometric terms. We present necessary conditions for the invariant measure…

Probability · Mathematics 2014-07-03 Yanting Chen , Richard J. Boucherie , Jasper Goseling

We relate the topology of the Morse boundary of a group to geometric and algorithmic properties of the group. In particular, we show that a group has $\sigma$-compact Morse boundary if and only if it is Morse local-to-global. We also…

Group Theory · Mathematics 2026-05-13 Carolyn Abbott , Stefanie Zbinden

We introduce a new type of boundary for proper geodesic spaces, called the Morse boundary, that is constructed with rays that identify the "hyperbolic directions" in that space. This boundary is a quasi-isometry invariant and thus produces…

Geometric Topology · Mathematics 2023-06-27 Matthew Cordes

We establish spectral rigidity for spherically symmetric manifolds with boundary and interior interfaces determined by discontinuities in the metric under certain conditions. Rather than a single metric, we allow two distinct metrics in…

Analysis of PDEs · Mathematics 2023-12-08 Joonas Ilmavirta , Maarten V. de Hoop , Vitaly Katsnelson

We show that manifolds admitting special generic maps also admit nice generalized multisections. Special generic maps are natural generalized versions of Morse functions with exactly two singular points on closed manifolds, characterizing…

General Topology · Mathematics 2022-11-01 Naoki Kitazawa

Let \((M,\omega)\) be a compact symplectic manifold of dimension \(2n\) endowed with a Hamiltonian circle action with only isolated fixed points. Whenever \(M\) admits a toric \(1\)-skeleton \(\mathcal{S}\), which is a special collection of…

Algebraic Topology · Mathematics 2020-01-08 Isabelle Charton

We prove that, if M is a compact oriented manifold of dimension 4k+3, where k>0, such that pi_1(M) is not torsion-free, then there are infinitely many manifolds that are homotopic equivalent to M but not homeomorphic to it. To show the…

Geometric Topology · Mathematics 2014-11-11 Stanley Chang , Shmuel Weinberger

In this paper a geometric approach toward stable homotopy groups of spheres, based on the Pontrjagin-Thom construction is proposed. From this approach a new proof of Hopf Invariant One Theorem by J.F.Adams for all dimensions except…

Geometric Topology · Mathematics 2008-01-10 Petr M. Akhmet'ev

In the first part of this paper, we consider smooth maps from a compact orientable 3-manifold without boundary to the 2-sphere. We give a geometric criterion to decide whether two given maps are homotopic, based on the sets of points where…

Dynamical Systems · Mathematics 2007-05-23 Emmanuel Dufraine

A classical result by Marston Morse asserts that on some ellipsoids of ${\mathbb R}^3$ there exists exactly 3 closed and simple geodesics. The goal of this presentation is to prove that this rigidity result does not extend to higher…

Differential Geometry · Mathematics 2019-05-20 Tristan Rivière