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We study manifolds arising as spaces of sections of complex manifolds fibering over the projective line with normal bundle of each section isomorphic to several copies of O(k). Such manifolds provide a natural setting for certain integrable…

Differential Geometry · Mathematics 2007-05-23 Roger Bielawski

We show that the Hausdorff reflection preserves the shape type of spaces. Some examples as well as the applicability in inverse limits of finite spaces are presented.

General Topology · Mathematics 2024-12-11 Diego Mondéjar

1) In 1976, looking at simple finite-dimensional complex Lie superalgebras, J.~Bernstein and I, and independently M.~Duflo, observed that certain divergence-free vectorial Lie superalgebras have deformations with odd parameters and…

Representation Theory · Mathematics 2024-09-24 Dimitry Leites

The Hopf sign conjecture states that a compact Riemannian 2d-manifold M of positive curvature has Euler characteristic X(M)>0 and that in the case of negative curvature X(M) (-1)^d >0. The Hopf product conjecture asks whether a positive…

Differential Geometry · Mathematics 2020-01-07 Oliver Knill

Let $f\colon M^{2n}\to\mathbb{R}^{2n+p}$ denote an isometric immersion of a Kaehler manifold of complex dimension $n\geq 2$ into Euclidean space with codimension $p$. If $2p\leq 2n-1$, we show that generic rank conditions on the second…

Differential Geometry · Mathematics 2023-08-30 A. de Carvalho , S. Chion , M. Dajczer

We investigate ruled surfaces in 3d Riemannian manifolds, i.e., surfaces foliated by geodesics. In 3d space forms, we find the striction curve, distribution parameter, and the first and second fundamental forms, from which we obtain the…

Differential Geometry · Mathematics 2022-09-21 Luiz C. B. da Silva , José D. da Silva

In this paper, as a continuation of [30], we consider the Gromov-Hausdorff convergence and collapsing in the family of compact Riemannian manifolds with boundary satisfying lower bounds on the sectional curvatures of interior manifolds,…

Differential Geometry · Mathematics 2025-04-09 Takao Yamaguchi , Zhilang Zhang

A submanifold of a pseudo-Riemannian manifold is said to have parallel mean curvature vector if the mean curvature vector field H is parallel as a section of the normal bundle. Submanifolds with parallel mean curvature vector are important…

Differential Geometry · Mathematics 2013-07-02 Bang-Yen Chen

Small codimensional embedded manifolds defined byequations of small degree are Fano and covered by lines. They are complete intersections exactly when the variety of lines through a general point is so and has the right codimension. This…

Algebraic Geometry · Mathematics 2014-11-25 Paltin Ionescu , Francesco Russo

We give some classifications of biharmonic hypersurfaces with constant scalar curvature. These include biharmonic Einstein hypersurfaces in space forms, compact biharmonic hypersurfaces with constant scalar curvature in a sphere, and some…

Differential Geometry · Mathematics 2017-08-30 Shun Maeta , Ye-Lin Ou

If M is a smooth compact connected Riemannian manifold, let P(M) denote the Wasserstein space of probability measures on M. We describe a geometric construction of parallel transport of some tangent cones along geodesics in P(M). We show…

Differential Geometry · Mathematics 2017-01-10 John Lott

The paper is devoted to the study of the Gromov-Hausdorff proper class, consisting of all metric spaces considered up to isometry. In this class, a generalized Gromov-Hausdorff pseudometric is introduced and the geometry of the resulting…

Metric Geometry · Mathematics 2021-10-13 Semeon A. Bogaty , Alexey A. Tuzhilin

While classical data analysis has addressed observations that are real numbers or elements of a real vector space, at present many statistical problems of high interest in the sciences address the analysis of data that consist of more…

Statistics Theory · Mathematics 2023-08-15 Zhigang Yao , Jiaji Su , Bingjie Li , Shing-Tung Yau

The classical approach to the study of dynamical systems consists in representing the dynamics of the system in the form of a "source-sink", that means identifying an attractor-repeller pair, which are attractor-repellent sets for all other…

Dynamical Systems · Mathematics 2022-10-18 Elena Nozdrinova , Olga Pochinka , Ekaterina Tsaplina

We consider generic families $X_\param$ of smooth dynamical systems depending on parameters $\param\in P$ where $P$ is a 2-dimensional simply connected domain and assume that each $X_\param$ only has a finite number of restpoints and…

Dynamical Systems · Mathematics 2025-02-06 David A Rand , Meritxell Saez

In this paper we present another notion of a smooth manifold with corners and relate it to the commonly used concept in the literature. Afterwards we introduce complex manifolds with corners and show that if $M$ is a compact (respectively…

Differential Geometry · Mathematics 2010-01-04 Christoph Wockel

Given a manifold (or, more generally, a developable orbifold) $M_0$ and two closed Riemannian manifolds $M_1$ and $M_2$ with a finite covering map to $M_0$, we give a spectral characterisation of when they are equivalent Riemannian covers…

Differential Geometry · Mathematics 2021-07-02 Gunther Cornelissen , Norbert Peyerimhoff

We consider the question: ``How bad can the deformation space of an object be?'' The answer seems to be: ``Unless there is some a priori reason otherwise, the deformation space may be as bad as possible.'' We show this for a number of…

Algebraic Geometry · Mathematics 2007-05-23 Ravi Vakil

Let G be a unimodular Lie group, X a compact manifold with boundary, and M the total space of a principal bundle G--> M-->X so that M is also a strongly pseudoconvex complex manifold. In this work, we show that if there exists a point p in…

Complex Variables · Mathematics 2012-05-24 Giuseppe Della Sala , Joe J. Perez

We show that for a noncollapsing sequence of closed, connected, oriented Riemannian manifolds with Ricci curvature uniformly bounded from below and diameter uniformly bounded above, Gromov-Hausdorff convergence essentially agrees with…

Differential Geometry · Mathematics 2015-10-27 Rostislav Matveev , Jacobus W. Portegies