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To any spectral triple (A,D,H) a dimension d is associated, in analogy with the Hausdorff dimension for metric spaces. Indeed d is the unique number, if any, such that |D|^-d has non trivial logarithmic Dixmier trace. Moreover, when d is…

Operator Algebras · Mathematics 2007-05-23 Daniele Guido , Tommaso Isola

We describe a general technique to study Dirac operators on noncommutative spaces under some additional assumptions. The main idea is to capture the compact resolvent condition in a combinatorial set up. Using this, we then prove that for a…

Operator Algebras · Mathematics 2007-05-23 Partha Sarathi Chakraborty , Arupkumar Pal

This paper extends the notion of a spectral triple to a relative spectral triple, an unbounded analogue of a relative Fredholm module for an ideal $J\triangleleft A$. Examples include manifolds with boundary, manifolds with conical…

K-Theory and Homology · Mathematics 2019-11-28 Iain Forsyth , Magnus Goffeng , Bram Mesland , Adam Rennie

This article is concerned with a generalisation of Connes' noncommutative framework. This is achieved by a general study of spectral triples, in particular through an analysis of the role played by the Dirac operator. The Dirac operator is…

Mathematical Physics · Physics 2018-06-27 Nikhil Kalyanapuram

Let $q=|q|e^{i\pi\theta},\,\theta\in(-1,1],$ be a nonzero complex number such that $|q|\neq 1$ and consider the compact quantum group $U_q(2)$. For $\theta\notin\mathbb{Q}\setminus\{0,1\}$, we obtain the $K$-theory of the $C^*$-algebra…

Operator Algebras · Mathematics 2026-01-19 Satyajit Guin , Bipul Saurabh

We study spectral triples over noncommutative principal U(1) bundles. Basing on the classical situation and the abstract algebraic approach, we propose an operatorial definition for a connection and compatibility between the connection and…

Mathematical Physics · Physics 2013-11-21 Ludwik Dabrowski , Andrzej Sitarz

We introduce a family of spectral triples that describe the curved noncommutative two-torus. The relevant family of new Dirac operators is given by rescaling one of two terms in the flat Dirac operator. We compute the dressed scalar…

Quantum Algebra · Mathematics 2018-06-04 Ludwik Dabrowski , Andrzej Sitarz

We propose an expansion of the definition of almost-commutative spectral triple that accommodates non-trivial fibrations and is stable under inner fluctuation of the metric, and then prove a reconstruction theorem for almost-commutative…

Mathematical Physics · Physics 2012-07-02 Branimir Ćaćić

We introduce to spectral noncommutative geometry the notion of tangled spectral triple, which encompasses the anisotropies arising in parabolic geometry as well as the parabolic commutator bounds arising in so-called "bad Kasparov…

Operator Algebras · Mathematics 2026-02-25 Magnus Fries , Magnus Goffeng , Ada Masters

Given a free action of a compact Lie group $G$ on a unital C*-algebra $\mathcal{A}$ and a spectral triple on the corresponding fixed point algebra $\mathcal{A}^G$, we present a systematic and in-depth construction of a spectral triple on…

Operator Algebras · Mathematics 2022-01-24 Kay Schwieger , Stefan Wagner

Given a spectral triple $(\mathcal{A},\mathcal{H},D)\,$ Connes associated a canonical differential graded algebra $\,\Omega_D^\bullet(\mathcal{A})$. However, so far this has been computed for very few special cases. We identify suitable…

Quantum Algebra · Mathematics 2014-04-11 Partha Sarathi Chakraborty , Satyajit Guin

We initiate the study of a q-deformed geometry for quantum SU(2). In contrast with the usual properties of a spectral triple, we get that only twisted commutators between algebra elements and our Dirac operator are bounded. Furthermore, the…

Quantum Algebra · Mathematics 2015-05-30 Jens Kaad , Roger Senior

Two examples of spectral triples with non-integer dimension spectrum are considered. These triples involve commutative C*-algebras. The first example has complex dimension spectrum and trivial differential algebra. The other is a parameter…

Mathematical Physics · Physics 2008-09-29 R. Trinchero

We investigate the notion of subsystem in the framework of spectral triple as a generalized notion of noncommutative submanifold. In the case of manifolds, we consider several conditions on Dirac operators which turn embedded submanifolds…

Mathematical Physics · Physics 2024-04-26 Paolo Bertozzini , Wanchalerm Sucpikarnon , Apimook Watcharangkool

The aim of this paper is to present a possible framework for incorporating a superspace formulation of supersymmetry into the formalism of noncommutative geometry \`a la Alain Connes. In analogy with the almost-commutative (AC) manifold…

Mathematical Physics · Physics 2020-04-22 Thomas E. Williams

The spectral action on the equivariant real spectral triple over \A(SU_q(2)) is computed explicitly. Properties of the differential calculus arising from the Dirac operator are studied and the results are compared to the commutative case of…

Mathematical Physics · Physics 2010-11-02 B. Iochum , C. Levy , A. Sitarz

We study a commuting triple of bounded operators $(A, B, P)$ which has the tetrablock as a spectral set.

Functional Analysis · Mathematics 2015-11-23 Tirthankar Bhattacharyya

We look at various forms of spectrum and associated pseudospectrum that can be defined for noncommuting $d$-tuples of Hermitian elements of a $C^*$-algebra. The emphasis is on theoretical calculations of examples, in particular for…

Operator Algebras · Mathematics 2024-03-08 Alexander Cerjan , Vasile Lauric , Terry A. Loring

The author's recent results on spectral invariant dense subalgebras of C*-algebras associated with dynamical systems are summarized. If G is a compactly generated polynomial growth Type R Lie group, and the action of G on S(M) (Schwartz…

funct-an · Mathematics 2016-02-15 Larry B. Schweitzer

Examples of noncommutative self-coverings are described, and spectral triples on the base space are extended to spectral triples on the inductive family of coverings, in such a way that the covering projections are locally isometric. Such…

Operator Algebras · Mathematics 2016-12-21 Valeriano Aiello , Daniele Guido , Tommaso Isola