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We call a von Neumann algebra with finite dimensional center a multifactor. We introduce an invariant of bimodules over $\rm II_1$ multifactors that we call modular distortion, and use it to formulate two classification results. We first…

Operator Algebras · Mathematics 2025-06-06 Marcel Bischoff , Ian Charlesworth , Samuel Evington , Luca Giorgetti , David Penneys

Conformal inclusions of chiral conformal field theories, or more generally inclusions of quantum field theories, are described in the von Neumann algebraic setting by nets of subfactors, possibly with infinite Jones index if one takes…

Operator Algebras · Mathematics 2022-11-01 Marcel Bischoff , Simone Del Vecchio , Luca Giorgetti

For any finite dimensional C^*-algebra A, we give an endomorphism \Phi of the hyperfinite II_1 factor R of finite Jones index such that: for all k \in \mathbb {N}, \Phi^k (R)' \cap R= \otimes^k A. The Jones index [R: \Phi (R)]= (rank…

Operator Algebras · Mathematics 2007-05-23 Hsiang-Ping Huang

We introduce a notion of planar algebra, the simplest example of which is a vector space of tensors, closed under planar contractions. A planar algebra with suitable positivity properties produces a finite index subfactor of a II_1 factor,…

Quantum Algebra · Mathematics 2007-05-23 Vaughan F. R. Jones

Using various finite dimensional approximation properties, four convex subsets of the tracial space of a unital C*-algebra are defined. Applications of these tracial invariants include: (1) An analogue of Szego's limit theorem for arbitrary…

Operator Algebras · Mathematics 2007-05-23 Nathanial P. Brown

We present more planar algebraic construction of subfactors than those of Guionet-Jones-Shlyakhtenko-Walker and Kodiyalam-Sunder which start from a subfactor planar algebra and give in a direct way a subfactor of the same standard invariant…

Operator Algebras · Mathematics 2013-03-20 Wunghun Ri , Gwangho Jong

We examine the notion of $\alpha$-strong singularity for subfactors of a \IIi factor, which is a metric quantity that relates the distance between a unitary in the factor and a subalgebra with the distance between that subalgebra and its…

Operator Algebras · Mathematics 2014-02-26 Pinhas Grossman , Alan Wiggins

Given a finite index subfactor, we show that the {\em affine morphisms at zero level} in the affine category over the planar algebra associated to the subfactor is isomorphic to the fusion algebra of the subfactor as a *-algebra. This…

Quantum Algebra · Mathematics 2026-01-01 Paramita Das , Shamindra Kumar Ghosh , Ved Prakash Gupta

We define Jones's planar algebra as a map of multicategories and constuct a planar algebra starting from a 1-cell in a pivotal strict 2-category. We prove finiteness results for the affine representations of finite depth planar algebras. We…

Quantum Algebra · Mathematics 2010-04-07 Shamindra Kumar Ghosh

We introduce the notion of finite right (respectively left) numerical index on a bimodule $X$ over C*-algebras A and B with a bi-Hilbertian structure. This notion is based on a Pimsner-Popa type inequality. The right (respectively left)…

Operator Algebras · Mathematics 2016-09-07 T. Kajiwara , C. Pinzari , Y. Watatani

Let $M$ be a II$_1$ factor with a von Neumann subalgebra $Q\subset M$ that has infinite index under any projection in $Q'\cap M$ (e.g., $Q$ abelian; or $Q$ an irreducible subfactor with infinite Jones index). We prove that given any…

Operator Algebras · Mathematics 2018-10-22 Sorin Popa

A {\it W$^*$-representation} of a II$_1$ subfactor $N\subset M$ with finite Jones index, $[M:N]<\infty$, is a non-degenerate commuting square embedding of $N\subset M$ into an inclusion of atomic von Neumann algebras $\oplus_{i\in I} \Cal…

Operator Algebras · Mathematics 2022-07-12 Sorin Popa

Graded rings provide a natural algebraic framework for encoding symmetry via decompositions into homogeneous components indexed by a group, together with multiplication rules reflecting the group operation. Among graded rings, strongly…

Rings and Algebras · Mathematics 2026-05-12 Joakim Arnlind , Stefan Wagner

We give a characterization of extremal irreducible discrete subfactors $(N\subseteq M, E)$ where $N$ is type ${\rm II}_1$ in terms of connected W*-algebra objects in rigid C*-tensor categories. We prove an equivalence of categories where…

Operator Algebras · Mathematics 2018-01-09 Corey Jones , David Penneys

We construct new hyperfinite subfactors with Temperley-Lieb-Jones (TLJ) standard invariant and Jones indices between $4$ and $3 + \sqrt{5}$. Our subfactors occur at all indices between $4$ and $5$ at which finite depth, hyperfinite…

Operator Algebras · Mathematics 2025-10-23 Dietmar Bisch , Julio Cáceres

We construct inclusions of the form $(B_0\otimes P)^G\subset (B_1\otimes P)^G$, where $G$ is a compact quantum group of Kac type acting on an inclusion of finite dimensional $\c^*$-algebras $B_0\subset B_1$ and on a $II_1$ factor $P$. Under…

Operator Algebras · Mathematics 2007-05-23 Teodor Banica

We prove that a finite index regular inclusion of $II_1$-factors with commutative first relative commutant is always a crossed product subfactor with respect to a minimal action of a biconnected weak Kac algebra. Prior to this, we prove…

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

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

We review the framework subfactors provide for understanding modular invariants. We discuss the structure of a generalized Longo-Rehren subfactor and the relationship between the coupling matrices of such subfactors, modular invariance and…

Operator Algebras · Mathematics 2007-05-23 David E Evans

We show a close relationship between non-degenerate smooth commuting squares of $II_1$-factors with all inclusions of finite index and inclusions of subfactor planar algebras by showing that each leads to a construction of the other. One…

Operator Algebras · Mathematics 2019-12-11 Keshab Chandra Bakshi , Vijay Kodiyalam