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Related papers: Lattice of intermediate subalgebras

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We show that the angle between intermediate $C^*$-subalgebras of an inclusion of simple $C^*$-algebras with finite Watatani index is stable. The notion of angle is instrumental in providing a bound for the cardinality of the lattice of…

Operator Algebras · Mathematics 2026-01-19 Keshab Chandra Bakshi , Satyajit Guin , Debabrata Jana

Motivated by [2] and [5], the notions of interior and exterior angles between a pair of compatible intermediate W*-subalgebras of an inclusion of W*-algebras with a normal conditional expectation with finite probabilistic index are…

Operator Algebras · Mathematics 2026-02-04 Ved Prakash Gupta , Deepika Sharma

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

This paper studies Frobenius subalgebra posets in abelian monoidal categories and shows that, under general conditions--satisfied in all semisimple tensor categories over the complex field--they collapse to lattices through a rigidity…

Quantum Algebra · Mathematics 2025-10-27 Mainak Ghosh , Sebastien Palcoux

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

We define a canonical relative commutant planar algebra from a strongly Markov inclusion of finite von Neumann algebras. In the case of a connected unital inclusion of finite dimensional C*-algebras with the Markov trace, we show this…

Operator Algebras · Mathematics 2010-07-20 Vaughan F. R. Jones , David Penneys

Given a unital inclusion of simple $C^*$-algebras equipped with a conditional expectation of index-finite type, we study Fourier transforms and rotation operators and introduce the reflection operators on the relative commutants. We prove…

Operator Algebras · Mathematics 2026-01-19 Keshab Chandra Bakshi , Satyajit Guin , Biplab Pal , Sruthymurali

Given an irreducible lattice $\Gamma$ in the product of higher rank simple Lie groups, we prove a co-finiteness result for the $\Gamma$-invariant von Neumann subalgebras of the group von Neumann algebra $\mathcal{L}(\Gamma)$, and for the…

Operator Algebras · Mathematics 2022-02-10 Mehrdad Kalantar , Nikolaos Panagopoulos

We prove that an inclusion $\mathcal{B} \subset \mathcal{A}$ of simple unital $C^*$-algebras with a finite-index conditional expectation is regular if and only if there exists a finite group $G$ that admits a cocycle action…

Operator Algebras · Mathematics 2026-01-01 Keshab Chandra Bakshi , Ved Prakash Gupta

The notion of index for inclusions of von Neumann algebras goes back to a seminal work of Jones on subfactors of type ${I\!I}_1$. In the absence of a trace, one can still define the index of a conditional expectation associated to a…

Operator Algebras · Mathematics 2022-05-04 Luca Giorgetti

Given an irreducible local conformal net A of von Neumann algebras on the circle and a finite-index conformal subnet B of A, we show that A is completely rational iff B is completely rational. In particular this extends a result of F. Xu…

Operator Algebras · Mathematics 2011-04-06 Roberto Longo

Growing out of the initial connections between subfactors and knot theory that gave rise to the Jones polynomial, Jones' axiomatization of the standard invariant of an extremal finite index $II_1$ subfactor as a spherical $C^*$-planar…

Operator Algebras · Mathematics 2011-11-08 Michael Burns

We introduce the category of C*-discrete inclusions of C*-algebras $A\subset B$ with a faithful conditional expectation $E:B\twoheadrightarrow A$. This class includes many examples such as finite Watatani index inclusions, and also abundant…

Operator Algebras · Mathematics 2026-01-06 Roberto Hernández Palomares , Brent Nelson

We prove that finiteness of the index of the intersection of a finite set of finite index subalgebras in a von Neumann algebra (with small centre) is equivalent to the finite dimensionality of the algebra generated by the conditional…

Operator Algebras · Mathematics 2007-05-23 Vaughan F. R. Jones , Feng Xu

This paper originates from a naive attempt to establish various non-commutative Fourier theoretic inequalities for an inclusion of simple C*-algebras equipped with a conditional expectation of index-finite type. In this setting, we discuss…

Operator Algebras · Mathematics 2026-01-19 Keshab Chandra Bakshi , Satyajit Guin , Sruthymurali

In the given article it is introduced new notions of a C$^*$-algebra of von Neumann type I and C$^*$-algebras of types I$_n$, II, II$_1$, II$_\infty$ and III. It is proved that any GCR-algebra is a C$^*$-algebra of von Neumann type I, and a…

Operator Algebras · Mathematics 2015-08-18 Arzikulov Farhodjon

For all transcendental parameters, the irrational rotation algebra is shown to contain infinitely many C*-subalgebras satisfying the following properties. Each subalgebra is isomorphic to a direct sum of two matrix algebras of the same…

Operator Algebras · Mathematics 2007-05-23 S. Walters

A subalgebra $\mathcal{A}$ of a $C^*$-algebra $\mathcal{M}$ is logmodular (resp. has factorization) if the set $\{a^*a; a\text{ is invertible with }a,a^{-1}\in\mathcal{A}\}$ is dense in (resp. equal to) the set of all positive and…

Operator Algebras · Mathematics 2021-01-05 B. V. Rajarama Bhat , Manish Kumar

Subfactor theory provides a tool to analyze and construct extensions of Quantum Field Theories, once the latter are formulated as local nets of von Neumann algebras. We generalize some of the results of [LR95] to the case of extensions with…

Operator Algebras · Mathematics 2018-04-11 Simone Del Vecchio , Luca Giorgetti

According to J. Feldman and C. Moore's well-known theorem on Cartan subalgebras, a variant of the group measure space construction gives an equivalence of categories between twisted countable standard measured equivalence relations and…

Operator Algebras · Mathematics 2008-03-18 Jean Renault
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