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Bivariant (equivariant) K-theory is the standard setting for non-commutative topology. We may carry over various techniques from homotopy theory and homological algebra to this setting. Here we do this for some basic notions from…

K-Theory and Homology · Mathematics 2015-10-23 Ralf Meyer , Ryszard Nest

We establish a large class of homotopy coherent Morita-equivalences of Dold-Kan type relating diagrams with values in any weakly idempotent complete additive $\infty$-category; the guiding example is an $\infty$-categorical Dold-Kan…

Representation Theory · Mathematics 2022-03-18 Tashi Walde

We study scattered piecewise interpretable Hilbert spaces from a model theoretic point of view. We establish strong connections between the Hilbert space structure theorems of [Chevalier Hrushovski 2021] and the model theoretic notions of…

Logic · Mathematics 2022-09-13 Alexis Chevalier

Modeling videos and image-sets as linear subspaces has proven beneficial for many visual recognition tasks. However, it also incurs challenges arising from the fact that linear subspaces do not obey Euclidean geometry, but lie on a special…

Computer Vision and Pattern Recognition · Computer Science 2014-07-07 Mehrtash T. Harandi , Mathieu Salzmann , Sadeep Jayasumana , Richard Hartley , Hongdong Li

A topological group is constructed which is homotopy equivalent to the pointed loop space of a path-connected Riemannian manifold $M$ and which is given in terms of "composable small geodesics" on $M$. This model is analogous to J. Milnor's…

Algebraic Topology · Mathematics 2008-06-05 A. Bahri , F. R. Cohen

We show that (for the weak operator topology) the set of unitary operators on a separable infinite-dimensional Hilbert space is residual in the set of all contractions. The analogous result holds for isometries and the strong operator…

Functional Analysis · Mathematics 2014-12-02 Tanja Eisner

In this paper we provide descriptions of the Whitehead groups with coefficients in a ring of the Hilbert modular group and its reduced version, as well as for the topological K-theory of $C^*$-algebras, after tensoring with $\mathbb{Q}$, by…

K-Theory and Homology · Mathematics 2017-06-16 Luis Jorge Sánchez Saldaña , Mario Velásquez

We show that in a weak globular $\omega$-category, all composition operations are equivalent and commutative for cells with sufficiently degenerate boundary, which can be considered a higher-dimensional generalisation of the Eckmann-Hilton…

Category Theory · Mathematics 2025-12-22 Thibaut Benjamin , Ioannis Markakis , Wilfred Offord , Chiara Sarti , Jamie Vicary

Given any model category, or more generally any category with weak equivalences, its simplicial localization is a simplicial category which can rightfully be called the "homotopy theory" of the model category. There is a model category…

Algebraic Topology · Mathematics 2007-05-23 Julia E. Bergner

We prove an h-principle with boundary condition for a certain class of topological spaces valued sheaves. The techniques used in the proof come from the study of the homotopy type of the cobordism categories, and they are of simplicial and…

Algebraic Topology · Mathematics 2015-06-16 Emanuele Dotto

We present a method for computing the Hilbert series of the algebra of invariants of the complex symplectic and orthogonal groups acting on graded noncommutative algebras with homogeneous components which are polynomial modules of the…

Rings and Algebras · Mathematics 2019-02-18 Vesselin Drensky , Elitza Hristova

We build model structures on the category of equivariant simplicial operads with a fixed set of colors, with weak equivalences determined by families of subgroups. In particular, by specifying to the family of graph subgroups (or, more…

Algebraic Topology · Mathematics 2022-04-20 Peter Bonventre , Luis Alexandre Pereira

We show that the hermitian K-theory space of a commutative ring R can be identified, up to A^1-homotopy, with the group completion of the groupoid of oriented finite Gorenstein R-algebras, i.e., finite locally free R-algebras with…

Algebraic Geometry · Mathematics 2022-09-14 Marc Hoyois , Joachim Jelisiejew , Denis Nardin , Maria Yakerson

After introducing some motivations for this survey, we describe a formalism to parametrize a wide class of algebraic structures occurring naturally in various problems of topology, geometry and mathematical physics. This allows us to define…

Algebraic Topology · Mathematics 2016-12-16 Sinan Yalin

We develop a notion of rank one properly convex domains (or Hilbert geometries) in the real projective space. This is in the spirit of rank one non-positively curved Riemannian manifolds and CAT(0) spaces. We define rank one isometries for…

Geometric Topology · Mathematics 2025-06-11 Mitul Islam

We give an affirmative answer to the question whether there exist Lie algebras for suitable closed subgroups of the unitary group $U(\mathcal{H})$ in a Hilbert space $\mathcal{H}$ with $U(\mathcal{H})$ equipped with the strong operator…

Operator Algebras · Mathematics 2017-08-23 Hiroshi Ando , Yasumichi Matsuzawa

Let $H$ be an infinite-dimensional complex Hilbert space and let ${\mathcal L}(H)$ be the logic formed by all closed subspaces of $H$. For every natural $k$ we denote by ${\mathcal G}_{k}(H)$ the Grassmannian consisting of $k$-dimensional…

Combinatorics · Mathematics 2015-12-17 Mark Pankov

This paper gives an introduction to the homotopy theory of quasi-categories. Weak equivalences between quasi-categories are characterized as maps which induce equivalences on a naturally defined system of groupoids. These groupoids…

Category Theory · Mathematics 2019-09-19 J. F. Jardine

In this paper, Lusternik-Schinrelmann and geometric category of finite spaces are considered. We define new numerical invariants of these spaces derived from the geometric category and present an algorithmic approach for its effective…

Algebraic Topology · Mathematics 2022-09-30 Manuel Cárdenas , Ramón Flores , Antonio Quintero , Maria Trinidad Villar-Liñán

The category of Hilbert modules may be interpreted as a naive quantum field theory over a base space. Open subsets of the base space are recovered as idempotent subunits, which form a meet-semilattice in any firm braided monoidal category.…

Category Theory · Mathematics 2018-03-05 Pau Enrique Moliner , Chris Heunen , Sean Tull