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The Sierpinski gasket admits a locally isometric ramified self-covering. A semifinite spectral triple is constructed on the resulting solenoidal space, and its main geometrical features are discussed.

Operator Algebras · Mathematics 2021-03-03 Valeriano Aiello , Daniele Guido , Tommaso Isola

It is well known that spinors on oriented Riemannian manifolds cannot be defined as sections of a vector bundle associated with the frame bundle. For this reason spin and spin^c structures are often introduced. In this paper we prove that…

Differential Geometry · Mathematics 2007-09-18 Shay Fuchs

We construct discrete versions of $\kappa$-Minkowski space related to a certain compactness of the time coordinate. We show that these models fit into the framework of noncommutative geometry in the sense of spectral triples. The dynamical…

High Energy Physics - Theory · Physics 2011-11-28 Bruno Iochum , Thierry Masson , Thomas Schücker , Andrzej Sitarz

We develop an approach to noncommutative algebraic geometry ``in the perturbative regime" around ordinary commutative geometry. Let R be a noncommutative algebra and A=R/[R,R] its commutativization. We describe what should be the formal…

Algebraic Geometry · Mathematics 2007-05-23 Mikhail Kapranov

A holomorphic triple over a compact Riemann surface consists of two holomorphic vector bundles and a holomorphic map between them. After fixing the topological types of the bundles and a real parameter, there exist moduli spaces of stable…

Algebraic Geometry · Mathematics 2016-09-07 Steven B. Bradlow , Oscar Garcia-Prada , Peter B. Gothen

The machinery of noncommutative geometry is applied to a space of connections. A noncommutative function algebra of loops closely related to holonomy loops is investigated. The space of connections is identified as a projective limit of…

High Energy Physics - Theory · Physics 2009-11-11 Johannes Aastrup , Jesper M. Grimstrup

We give a general construction of extended moduli spaces of topological D-branes as non-commutative algebraic varieties. This shows that noncommutative symplectic geometry in the sense of Kontsevich arises naturally in String Theory.

High Energy Physics - Theory · Physics 2009-11-11 C. I. Lazaroiu

The aim of the paper is to answer the following question: does $\kappa$-deformation fit into the framework of noncommutative geometry in the sense of spectral triples? Using a compactification of time, we get a discrete version of…

Mathematical Physics · Physics 2011-09-20 B. Iochum , T. Masson , Th. Schücker , A. Sitarz

We introduce a trilinear functional of differential one-forms for a finitely summable regular spectral triple with a noncommutative residue. We demonstrate that for a canonical spectral triple over a closed spin manifold it recovers the…

Quantum Algebra · Mathematics 2024-08-22 Ludwik Dąbrowski , Andrzej Sitarz , Paweł Zalecki

In this paper we construct odd finitely summable spectral triples based on length functions of bounded doubling on noncommutative solenoids. Our spectral triples induce a Leibniz Lip-norm on the state spaces of the noncommutative solenoids,…

Operator Algebras · Mathematics 2022-12-16 Carla Farsi , Therese Basa Landry , Nadia S. Larsen , Judith A. Packer

We characterize Riemannian orbifolds and their coverings in terms of metric geometry. In particular, we show that the metric double of a Riemannian orbifold along the closure of its codimension one stratum is a Riemannian orbifold and that…

Differential Geometry · Mathematics 2020-03-12 Christian Lange

In this paper we will show the following result: Let $\mathcal{N} $ be a complete (noncompact) connected orientable Riemannian three-manifold with nonnegative scalar curvature $S \geq 0$ and bounded sectional curvature $ K_{s} \leq K $.…

Differential Geometry · Mathematics 2017-03-28 Jose M. Espinar

We fully characterize those von Neumann algebras having the ball-covering property. We also study the ball-covering property of noncommutative symmetric spaces. In particular, we provide a number of new examples of non-separable…

Operator Algebras · Mathematics 2023-11-27 Jinghao Huang , Karimbergen Kudaybergenov , Rui Liu

In spin geometry, traceless cyclic homogeneous Riemannian manifolds equipped with a homogeneous spin structure can be viewed as the simplest manifolds after Riemannian symmetric spin spaces. In this paper, we give some characterizations and…

Differential Geometry · Mathematics 2015-04-30 P. M. Gadea , José Carmelo González-Dávila , José A. Oubiña

We show the existence of a natural Dirichlet-to-Neumann map on Riemannian manifolds with boundary and bounded geometry, such that the bottom of the Dirichlet spectrum is positive. This map regarded as a densely defined operator in the…

Differential Geometry · Mathematics 2021-06-03 Panagiotis Polymerakis

We review some applications of noncommutative geometry to the study of transverse geometry of Riemannian foliations and discuss open problems.

Differential Geometry · Mathematics 2007-05-23 Yuri Kordyukov

We study a noncommutative analogue of a spacetime foliated by spacelike hypersurfaces, in both Riemannian and Lorentzian signatures. First, in the classical commutative case, we show that the canonical Dirac operator on the total spacetime…

Mathematical Physics · Physics 2019-09-16 Koen van den Dungen

A topological space is called self-covering if it is a nontrivial cover of itself. We prove that a closed self-covering manifold $M$ with free abelian fundamental group fibers over a circle under certain assumptions. In particular, we give…

Geometric Topology · Mathematics 2025-01-14 Lizhen Qin , Yang Su , Botong Wang

Gelfand - Na\u{i}mark theorem supplies a one to one correspondence between commutative $C^*$-algebras and locally compact Hausdorff spaces. So any noncommutative $C^*$-algebra can be regarded as a generalization of a topological space.…

Operator Algebras · Mathematics 2014-10-28 Petr Ivankov

We study finite G-sets and their tensor product with Riemannian manifolds, and obtain results on isospectral quotients and covers. In particular, we show the following: if M is a compact connected Riemannian manifold (or orbifold) whose…

Group Theory · Mathematics 2014-09-05 Ori Parzanchevski