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In this paper we develop the theory of strongly singular subalgebras of von Neumann algebras, begun in earlier work. We mainly examine the situation of type $\tto$ factors arising from countable discrete groups. We give simple criteria for…

Operator Algebras · Mathematics 2013-02-26 Guyan Robertson , Allan M. Sinclair , Roger R. Smith

We study analogues of the radial subalgebras in free group factors (called the algebras of class functions) in the setting of compact quantum groups. For the free orthogonal quantum groups we show that they are not MASAs, as soon as we are…

Operator Algebras · Mathematics 2022-05-17 Jacek Krajczok , Mateusz Wasilewski

In this review, we present a general framework for the construction of Kac-Moody (KM) algebras associated to higher-dimensional manifolds. Starting from the classical case of loop algebras on the circle $\mathbb{S}^{1}$, we extend the…

High Energy Physics - Theory · Physics 2026-01-21 Rutwig Campoamor-Stursberg , Alessio Marrani , Michel Rausch de Traubenberg

This is a first of our papers devoted to "noncommutative topology and graph theory". Its origin is the paper math.QA/0002238 by I. Gelfand, V. Retakh, and R.L. Wilson where a new class of noncommutative algebras $Q_n$ was introduced. The…

Quantum Algebra · Mathematics 2007-05-23 Israel Gelfand , Sergei Gelfand , Vladimir Retakh

Using a family of graded algebra structures on a planar algebra and a family of traces coming from random matrix theory, we obtain a tower of non-commutative probability spaces, naturally associated to a given planar algebra. The associated…

Operator Algebras · Mathematics 2008-07-08 A. Guionnet , V. F. R. Jones , D. Shlyakhtenko

In this paper we analyse the structure of the Cuntz semigroup of certain $C(X)$-algebras, for compact spaces of low dimension, that have no $\mathrm{K}_1$-obstruction in their fibres in a strong sense. The techniques developed yield…

Operator Algebras · Mathematics 2011-01-26 Ramon Antoine , Francesc Perera , Luis Santiago

Given the maximal compact subalgebra $\mathfrak{k}(A)$ of a split-real Kac-Moody algebra $\mathfrak{g}(A)$ of type $A$, we study certain finite-dimensional representations of $\mathfrak{k}(A)$, that do not lift to the maximal compact…

Representation Theory · Mathematics 2025-01-15 Robin Lautenbacher , Ralf Köhl

We consider inclusions of type $(P\otimes A)^G\subset(P\otimes B)^G$, where $G$ is a compact quantum group of Kac type acting on a ${\rm II}_1$ factor $P$, and on a Markov inclusion of finite dimensional $C^*$-algebras $A\subset B$. In the…

Operator Algebras · Mathematics 2018-12-11 Teodor Banica

We obtain a series of new results on the problem of irreducibility of commuting varieties associated with symmetric pairs or, in other words, $Z_2$-graded simple Lie algebras. In particular, we present many examples of reducible commuting…

Algebraic Geometry · Mathematics 2019-05-01 Dmitri Panyushev , Oksana Yakimova

Affine Hecke algebras arise naturally in the study of smooth representations of reductive $p$-adic groups. Finite dimensional complex representations of affine Hecke algebras (under some restriction on the isogeny class and the parameter…

Representation Theory · Mathematics 2014-07-01 Xuhua He

We introduce Hopf algebroid covariance on Woronowicz's differential calculus. Using it, we develop quite a general framework of noncommutative complex geometry that subsumes the one in [2]. We present transverse complex and K\"ahler…

Quantum Algebra · Mathematics 2021-05-11 Suvrajit Bhattacharjee , Indranil Biswas , Debashish Goswami

We consider epimorphisms from quantum minimal surface algebras onto involutroy subalgebras of split real simply-laced Kac-Moody algebras and provide examples of affine and finite type. We also provide epimorphisms onto such Kac-Moody…

Representation Theory · Mathematics 2021-05-21 Jens Hoppe , Ralf Köhl , Robin Lautenbacher

The purpose of this paper is to make the theory of vertex algebras trivial. We do this by setting up some categorical machinery so that vertex algebras are just ``singular commutative rings'' in a certain category. This makes it easy to…

Quantum Algebra · Mathematics 2007-05-23 Richard E. Borcherds

We develop theory of multiplicity maps for compact quantum groups, as an application, we obtain a complete classification of right coideal $C^*$-algebras of $C(SU_q(2))$ for $q\in [-1,1]\setminus \{0\}$. They are labeled with Dynkin…

Operator Algebras · Mathematics 2007-05-23 Reiji Tomatsu

We introduce the spin Hecke algebra, which is a q-deformation of the spin symmetric group algebra, and its affine generalization. We establish an algebra isomorphism which relates our spin (affine) Hecke algebras to the (affine)…

Representation Theory · Mathematics 2011-11-09 Weiqiang Wang

This note discusses recent new approaches to studying flopping curves on 3-folds. In a joint paper, the author and Michael Wemyss introduced a 3-fold invariant, the contraction algebra, which may be associated to such curves. It…

Algebraic Geometry · Mathematics 2015-11-06 Will Donovan

We construct a generalised notion of Kac-Moody algebras using smooth maps from the non-compact manifolds ${\cal M}=$SL$(2,\mathbb R)$ and ${\cal M}=$ SL$(2,\mathbb R)/U(1)$ to a finite-dimensional simple Lie group $G$. This construction is…

Mathematical Physics · Physics 2024-09-11 Rutwig Campoamor-Stursberg , Alessio Marrani , Michel Rausch de Traubenberg

We prove a number of results having to do with equipping type-I $\mathrm{C}^*$-algebras with compact quantum group structures, the two main ones being that such a compact quantum group is necessarily co-amenable, and that if the…

Operator Algebras · Mathematics 2020-08-11 Alexandru Chirvasitu , Jacek Krajczok , Piotr M. Sołtan

We define and discuss an extension of the SpinC quantization concept to odd-dimensional manifolds. After that we describe its relation to (the usual) even-dimensional SpinC quantization and how its famous properties like "Quantization…

Differential Geometry · Mathematics 2011-10-25 Johannes Fabian Meier

We introduce a notion of Mathieu-Zhao subspaces of vertex algebras. Among other things, we show that for a vertex algebra $V$ and its subspace $M$ that contains $C_2(V)$, $M$ is a Mathieu-Zhao subspace of $V$ if and only if the quotient…

Quantum Algebra · Mathematics 2018-06-19 Gaywalee Yamskulna