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The purpose of this note is to show that the construction of the C*-algebra for the space-time uncertainty relations which was introduced by Doplicher, Fredenhagen and Roberts fits comfortably into the strict deformation quantization…

funct-an · Mathematics 2008-02-03 Marc A. Rieffel

Given any irreducible inclusion $\mB \subset \mA$ of unital $C^*$-algebras with a finite-index conditional expectation $E: \mA \to \mB$, we show that the set of $E$-compatible intermediate $C^*$-subalgebras is finite, thereby generalizing a…

Operator Algebras · Mathematics 2026-01-01 Ved Prakash Gupta , Sumit Kumar

The concept of a relatively weakly injective pair of operator systems is introduced and studied in this paper, motivated by relative weak injectivity in the C*-algebra category. E. Kirchberg \cite{Kr} proved that the C*-algebra…

Operator Algebras · Mathematics 2014-05-13 Angshuman Bhattacharya

We present geometric characterizations of the partial isometries, unitaries, and invertible operators in C*-algebras and von Neumann algebras.

Operator Algebras · Mathematics 2007-05-23 Charles Akemann , Nik Weaver

In this short report, we give some new entropy inequalities based on R\'{e}nyi relative entropy and the observation made by Berta {\em et al} [arXiv:1403.6102]. These inequalities obtained extends some well-known entropy inequalities. We…

Quantum Physics · Physics 2014-04-16 Lin Zhang

We show that the new quantum extension of Renyi's \alpha-relative entropies, introduced recently by Muller-Lennert, Dupuis, Szehr, Fehr and Tomamichel, J. Math. Phys. 54, 122203, (2013), and Wilde, Winter, Yang, Commun. Math. Phys. 331,…

Quantum Physics · Physics 2015-02-17 Milan Mosonyi , Tomohiro Ogawa

We establish a reverse inequality for Tsallis relative operator entropy involving a positive linear map. In addition, we present converse of Ando's inequality, for each parameter. We give examples to compare our results with the known…

Functional Analysis · Mathematics 2018-11-16 H. R. Moradi , S. Furuichi

In this paper, we establish some reverses of the operator entropy inequalities under certain conditions by using the Mond-Pe\v{c}ari\'c method. In particular, we present {\tiny \begin{align*}…

Functional Analysis · Mathematics 2017-04-10 Mojtaba Bakherad , Ali Morassaei

In this paper we consider shift operators, self-adjoint, unitary and normal operators on the standard module over a unital C*-algebra A. We define various generalized spectra in A of these operators, give description of such spectra of…

Operator Algebras · Mathematics 2020-07-13 Stefan Ivkovic

A regular operator T on a Hilbert C^*-module is defined just like a closed operator on a Hilbert space, with the extra condition that the range of (I+T^*T) is dense. Semiregular operators are a slightly larger class of operators that may…

Operator Algebras · Mathematics 2007-05-23 Arupkumar Pal

In this article we continue to study the concept of entropy introduced in [4], [15]-[17]. We calculate entropy for a wider class of finite-dimensional operators in comparison with [15]. We also approximate the entropy of a unitary operator…

Dynamical Systems · Mathematics 2023-12-12 Andrei Chernyshev

We consider a two-parameter family of R\'enyi relative entropies $D_{\alpha,z}(\rho||\sigma)$ that are quantum generalisations of the classical R\'enyi divergence $D_{\alpha}(p||q)$. This family includes many known relative entropies (or…

Quantum Physics · Physics 2016-02-23 Koenraad M. R. Audenaert , Nilanjana Datta

We study non-selfadjoint operator algebras that can be entirely understood via their finite-dimensional representations. In contrast with the elementary matricial description of finite-dimensional $\mathrm{C}^*$-algebras, in the…

Operator Algebras · Mathematics 2018-06-04 Raphaël Clouâtre , Christopher Ramsey

We obtain an order sharp estimate for the distance from a given bounded operator $A$ on a Hilbert space to the set of normal operators in terms of $\|[A,A^*]\|$ and the distance to the set of invertible operators. A slightly modified…

Operator Algebras · Mathematics 2015-02-24 Ilya Kachkovskiy , Yuri Safarov

We extend the definitions of different types of quantum R\'enyi relative entropy from the finite dimensional setting of density matrices to density spaces of $C^*$-algebras. We show that those quantities (which trivially coincide in the…

Operator Algebras · Mathematics 2019-06-26 Lajos Molnár

Given a pair of intermediate $C^*$-subalgebras of a unital inclusion of simple $C^*$-algebras with a conditional expectation of finite Watatani index, we discuss the corresponding angle operator and its Fourier transform. We provide a…

Operator Algebras · Mathematics 2025-03-11 Keshab Chandra Bakshi , Satyajit Guin , Biplab Pal

We study the higher regularity of free boundaries in obstacle problems for integro-differential operators. Our main result establishes that, once free boundaries are $C^{1,\alpha}$, then they are $C^\infty$. This completes the study of…

Analysis of PDEs · Mathematics 2019-12-16 Nicola Abatangelo , Xavier Ros-Oton

In this paper we consider we study various classical operator ideals (for instance, the ideals of strictly (co)singular, weakly compact, Dunford-Pettis operators) either on $C^*$-algebras, or preduals of von Neumann algebras.

Operator Algebras · Mathematics 2013-09-24 T. Oikhberg , E. Spinu

Since their inception in the 30's by von Neumann, operator algebras have been used in shedding light in many mathematical theories. Classification results for self-adjoint and non-self-adjoint operator algebras manifest this approach, but a…

Operator Algebras · Mathematics 2021-01-20 Adam Dor-On , Søren Eilers , Shirly Geffen

In this paper we obtain some new refinements and reverses of Young's operator inequality. Extensions for convex functions of operators are also provided.

Functional Analysis · Mathematics 2015-10-07 Silvestru Sever Dragomir