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In this paper, I shall demonstrate that sufficiently high-dimensional closed positively-curved Riemannian manifolds are either diffeomorphic to a spherical space form, or isometric to a locally compact rank one symmetric space. This…

Metric Geometry · Mathematics 2016-08-05 Yashar Memarian

Many homogeneous, four-dimensional space-time geometries can be considered within real projective geometry, which yields a mathematically well-defined framework for their deformations and limits without the appearance of singularities.…

High Energy Physics - Theory · Physics 2024-07-22 Daniel Spitz

Rigidity results are obtained for Riemannian $d$-manifolds with $\sec \geqslant 1$ and spherical rank at least $d-2>0$. Conjecturally, all such manifolds are locally isometric to a round sphere or complex projective space with the…

Differential Geometry · Mathematics 2014-09-29 Benjamin Schmidt , Krishnan Shankar , Ralf Spatzier

The twistor construction for Riemannian manifolds is extended to the case of manifolds endowed with generalized metrics (in the sense of generalized geometry \`a la Hitchin). The generalized twistor space associated to such a manifold is…

Differential Geometry · Mathematics 2018-07-03 Johann Davidov

This paper looks at how changes of coordinates on a pseudo-Riemannian manifold induce homogeneous linear transformations on its tangent spaces. We see that a pseudo-orthonormal frame in a given tangent space is the basis for a set of…

General Physics · Physics 2022-11-15 Tom Lawrence

A 4-dimensional Riemannian manifold M, equipped with an additional tensor structure S, whose fourth power is minus identity, is considered. The structure S has a skew-circulant matrix with respect to some basis of the tangent space at a…

Differential Geometry · Mathematics 2020-07-08 Dimitar Razpopov , Iva Dokuzova

By analogy with algebraic geometry, we define a category of non-linear sheaves (quasi-coherent homotopy-sheaves of topological spaces) on projective toric varieties and prove a splitting result for its algebraic K-theory, generalising…

K-Theory and Homology · Mathematics 2010-07-30 Thomas Huettemann

This is an overview article. In his Habilitationsvortrag, Riemann described infinite dimensional manifolds parameterizing functions and shapes of solids. This is taken as an excuse to describe convenient calculus in infinite dimensions…

Differential Geometry · Mathematics 2016-04-08 Peter W. Michor

We classify smooth complex projective varieties $X \subset \proj^N$ of dimension $2s+1$ containing a linear subspace $\Lambda$ of dimension $s$ whose normal bundle $N_{\Lambda/X}$ is numerically effective.

Algebraic Geometry · Mathematics 2015-11-04 Carla Novelli , Gianluca Occhetta

We classify K\"ahler-Einstein manifolds which admit a K\"ahler immersion into a finite dimensional complex projective space endowed with the Fubini-Study metric, whose codimention is not greater than 3 and whose metric is rotation…

Differential Geometry · Mathematics 2016-12-06 Filippo Salis

Synthetic algebraic geometry is a new approach to algebraic geometry. It consists in using homotopy type theory extended with three axioms, together with the interpretation of these in a higher version of the Zariski topos, in order to do…

Algebraic Geometry · Mathematics 2025-10-24 Felix Cherubini , Thierry Coquand , Matthias Ritter , David Wärn

Modern machine learning increasingly leverages the insight that high-dimensional data often lie near low-dimensional, non-linear manifolds, an idea known as the manifold hypothesis. By explicitly modeling the geometric structure of data…

Machine Learning · Computer Science 2026-03-02 Willem Diepeveen , Deanna Needell

Hausdorff relation, topologically identifying points in a given space, belongs to elementary tools of modern mathematics. We show that if subtle enough mathematical methods are used to analyze this relation, the conclusions may be…

Mathematical Physics · Physics 2015-05-19 Michael Heller , Leszek Pysiak , Wieslaw Sasin

Based on the projective matrix spaces studied by B. Schwarz and A. Zaks, we study the notion of projective space associated to a C*-algebra A with a fixed projection p. The resulting space P(p) admits a rich geometrical structure as a…

Operator Algebras · Mathematics 2007-05-23 E. Andruchow , G. Corach , D. Stojanoff

We develop in detail the theory of c-projective geometry, a natural analogue of projective differential geometry adapted to complex manifolds. We realise it as a type of parabolic geometry and describe the associated Cartan or tractor…

Differential Geometry · Mathematics 2021-06-08 David M. J. Calderbank , Michael G. Eastwood , Vladimir S. Matveev , Katharina Neusser

It is shown that a locally geometrical structure of arbitrarily curved Riemannian space is defined by a deformed group of its diffeomorphisms

Differential Geometry · Mathematics 2020-06-11 Serhiy E. Samokhvalov

This paper explores the generalized projective Riemann curvature in Finsler geometry, focusing on the properties of projectively equivalent Finsler metrics and the invariance of their curvature structures under projective transformations.…

Differential Geometry · Mathematics 2025-11-25 Nasrin Sadeghzadeh , Masoumeh Yaghoubi

Differentiable rendering is a technique to connect 3D scenes with corresponding 2D images. Since it is differentiable, processes during image formation can be learned. Previous approaches to differentiable rendering focus on mesh-based…

Computer Vision and Pattern Recognition · Computer Science 2020-03-25 Cong Gao , Xingtong Liu , Wenhao Gu , Benjamin Killeen , Mehran Armand , Russell Taylor , Mathias Unberath

The mapping class group of a surface with one boundary component admits numerous interesting representations including as a group of automorphisms of a free group and as a group of symplectic transformations. Insofar as the mapping class…

Geometric Topology · Mathematics 2009-06-01 Jorgen Ellegaard Andersen , Alex James Bene , R. C. Penner

First we present a short overview of the long history of projectively flat Finsler spaces. We give a simple and quite elementary proof of the already known condition for the projective flatness, and we give a criterion for the projective…

Differential Geometry · Mathematics 2015-05-27 T. Q. Binh , D. Cs. Kertész , L. Tamássy