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This paper studies ways to represent an ordered topological vector space as a space of continuous functions, extending the classical representation theorems of Kadison and Schaefer. Particular emphasis is put on the class of semisimple…

Functional Analysis · Mathematics 2020-09-25 Josse van Dobben de Bruyn

We give an alternative argument for the classification of real bundle pairs over smooth symmetric surfaces and extend this classification to nodal symmetric surfaces. We also classify the homotopy classes of automorphisms of real bundle…

Algebraic Geometry · Mathematics 2015-12-23 Penka Georgieva , Aleksey Zinger

We prove that the complex of proper non-trivial non-degenerate subspaces of a finite-dimensional vector space endowed with a non-degenerate sesquilinear form is homotopy equivalent to a wedge of spheres. Additionally, we show that the same…

Combinatorics · Mathematics 2015-03-27 Alice Devillers , Ralf Köhl , Bernhard Muhlherr

We define the odd symplectic grassmannians and flag manifolds, which are smooth projective varieties equipped with an action of the odd symplectic group and generalizing the usual symplectic grassmannians and flag manifolds. Contrary to the…

Algebraic Geometry · Mathematics 2007-05-23 Ion Alexandru Mihai

The Grassmann manifold of linear subspaces is important for the mathematical modelling of a multitude of applications, ranging from problems in machine learning, computer vision and image processing to low-rank matrix optimization problems,…

Numerical Analysis · Mathematics 2024-01-09 Thomas Bendokat , Ralf Zimmermann , P. -A. Absil

In this paper, we prove various results on the topology of the Grassmannian of oriented 3-planes in Euclidean 6-space and compute its cohomology ring. We give self-contained proofs. These spaces come up when studying submanifolds of…

Algebraic Topology · Mathematics 2019-04-10 Mustafa Kalafat , Eyüp Yalçınkaya

Heterotic backgrounds with torsion preserving minimal supersymmetry in four dimensions can be obtained as orbifolds of principal $T^{2}$ bundles over $K3$. We consider a worldsheet description of these backgrounds as gauged linear…

High Energy Physics - Theory · Physics 2023-07-26 Dan Israel , Yann Proto

We study the geometry of non-homogeneous horospherical varieties. These have been classified by Pasquier and include the well-known odd symplectic Grassmannians. We focus our study on quantum cohomology, with a view towards Dubrovin's…

Algebraic Geometry · Mathematics 2024-12-11 Richard Gonzales , Clélia Pech , Nicolas Perrin , Alexander Samokhin

We identify a region $\Bbb{W}_{\f{1}{3}}$ in a Grassmann manifold $\grs{n}{m}$, not covered by a usual matrix coordinate chart, with the following important property. For a complete $n-$submanifold in $\ir{n+m} \, (n\ge 3, m\ge2)$ with…

Differential Geometry · Mathematics 2011-09-30 J. Jost , Y. L. Xin , Ling Yang

A natural explicit condition is given ensuring that an action of the multiplicative monoid of non-negative reals on a manifold F comes from homotheties of a vector bundle structure on F, or, equivalently, from an Euler vector field. This is…

Differential Geometry · Mathematics 2010-05-28 Janusz Grabowski , Mikolaj Rotkiewicz

We resolve a longstanding open problem by reformulating the Grassmannian fusion frames to the case of mixed dimensions and show that this satisfies the proper properties for the problem. In order to compare elements of mixed dimension, we…

Functional Analysis · Mathematics 2019-11-14 Peter G. Casazza , John I. Haas , Joshua Stueck , Tin T. Tran

We present an algebraic framework which simultaneously generalizes the notion of linear subspaces, matroids, valuated matroids, and oriented matroids. We call the resulting objects matroids over hyperfields. In fact, there are (at least)…

Combinatorics · Mathematics 2017-04-21 Matthew Baker , Nathan Bowler

We give a representation of canonical vector bundles over Grassmannian manifolds as non-compact affine symmetric spaces as well as their Cartan model in the group of the Euclidean motions.

Differential Geometry · Mathematics 2007-11-13 Bozidar Jovanovic

We present a framework to systematically address topological phases when finer partitionings of bands are taken into account, rather than only considering the two subspaces spanned by valence and conduction bands. Focusing on…

Mesoscale and Nanoscale Physics · Physics 2020-09-18 Adrien Bouhon , Tomáš Bzdušek , Robert-Jan Slager

We prove that three spaces of importance in topological combinatorics are homeomorphic to closed balls: the totally nonnegative Grassmannian, the compactification of the space of electrical networks, and the cyclically symmetric…

Combinatorics · Mathematics 2022-06-08 Pavel Galashin , Steven N. Karp , Thomas Lam

We construct smooth bundles with base and fiber products of two spheres whose total spaces have non-vanishing $\hat{A}$-genus. We then use these bundles to locate non-trivial rational homotopy groups of spaces of Riemannian metrics with…

Differential Geometry · Mathematics 2021-03-01 Georg Frenck , Jens Reinhold

We analyse the homotopy types of gauge groups of principal U(n)-bundles associated to pseudo Real vector bundles in the sense of Atiyah. We provide satisfactory homotopy decompositions of these gauge groups into factors in which the…

Algebraic Topology · Mathematics 2018-03-16 Michael West

Complex supermanifold structures being deformations of the exterior algebra of a holomorphic vector bundle, have been parametrized by orbits of a group on non-abelian cohomology by P. Green. For the case of odd dimension $4$ and $5$ an…

Complex Variables · Mathematics 2016-01-28 Matthias Kalus

Jacobi algebroids, that is graded Lie brackets on the Grassmann algebra associated with a vector bundle which satisfy a property similar to that of the Jacobi brackets, are introduced. They turn out to be equivalent to generalized Lie…

Differential Geometry · Mathematics 2009-11-07 Janusz Grabowski , Giuseppe Marmo

We prove that for every closed, connected, orientable, irreducible 3-manifold, there exists an alternating group A_n which is not the topological symmetry group of any graph embedded in the manifold. We also show that for every finite group…

Geometric Topology · Mathematics 2011-08-16 Erica Flapan , Harry Tamvakis