activity
20162026
most citedThe approximation property for locally compact quantum groups

2 citations · 7 across the 20 of their papers we have counts for

collaborators

22 papers

math.OA2026

Actions of quantum groups on dual operator spaces and their crossed products

Jason Crann, Joeri De Ro, Jacek Krajczok

We study the category of dual operator spaces equipped with an action of a locally compact quantum group . The Fubini crossed product functor $-\rtimes^\mathcal{F} \mat…

math.OA2026

Scaling automorphisms of compact quantum groups

Jacek Krajczok

In this short article we verify the conjecture proposed by P. M. Sołtan and the author, by proving that a second countable compact quantum group whose scaling automorphisms are inn…

math.OA2026

Crossed product functors associated to -pseudofunctions

Jacek Krajczok, Ebrahim Samei, Timo Siebenand +1

We show that the -pseudofunctions, which were recently shown to lead to exotic completions of group -algebras by Wiersma and the second named author, can be used to co…

math.OA2026

Braided quantum group - a case study

Jacek Krajczok, Piotr. M. Sołtan

We continue the study of the braided compact quantum group for complex satisfying introduced by Kasprzak, Meyer, Roy and Woronowicz (J. Noncommut.…

math.OA2025

The standard construction for cocycle twisted and braided tensor product W-algebras

K. De Commer, J. Krajczok

Given a locally compact quantum group and a (generalized) dual unitary -cocycle , any W-algebra with a -action can be twisted into a new…

math.OA2025

Asymptotic invariants for fusion algebras associated with compact quantum groups

Jacek Krajczok, Adam Skalski

We introduce and study certain asymptotic invariants associated with fusion algebras (equipped with a dimension function), which arise naturally in the representation theory of com…

math.OA2024★ 1 cited

Braided tensor product of von Neumann algebras

Kenny De Commer, Jacek Krajczok

We introduce a definition of braided tensor product of von Neumann algebras equipped with an action of a quasi-triangular qua…

math.OA2024

Cowling-Haagerup constant of the product of discrete quantum groups

Jacek Krajczok

We show that (central) Cowling-Haagerup constant of discrete quantum groups is multiplicative, which extends the result of Freslon to general (not necesarilly unimodular) discrete…

math.OA2023

The Covariant Stone-von Neumann Theorem for Locally Compact Quantum Groups

Lucas Hall, Leonard Huang, Jacek Krajczok +1

The Stone-von Neumann Theorem is a fundamental result which unified the competing quantum mechanical models of matrix mechanics and wave mechanics. It's mechanism of proof ultimate…

math.OA2023

Averaging multipliers on locally compact quantum groups

Matthew Daws, Jacek Krajczok, Christian Voigt

We study an averaging procedure for completely bounded multipliers on a locally compact quantum group with respect to a compact quantum subgroup. As a consequence we show that cent…

math.OA2023

On certain invariants of compact quantum groups

Jacek Krajczok, Piotr M. Sołtan

We introduce and study a number of invariants of locally compact quantum groups defined by their scaling and modular groups and the spectrum of their modular elements. Focusing mai…

math.OA2023

Separation properties for positive-definite functions on locally compact quantum groups and for associated von Neumann algebras

Jacek Krajczok, Adam Skalski

Using Godement mean on the Fourier-Stieltjes algebra of a locally compact quantum group we obtain strong separation results for quantum positive-definite functions associated to a…

math.OA2023★ 2 cited

The approximation property for locally compact quantum groups

Matthew Daws, Jacek Krajczok, Christian Voigt

We study the Haagerup--Kraus approximation property for locally compact quantum groups, generalising and unifying previous work by Kraus--Ruan and Crann. Along the way we discuss h…

math.OA2022★ 1 cited

Examples of compact quantum groups with a factor

Jacek Krajczok, Piotr M. Sołtan

For each we exhibit an uncountable family of compact quantum groups such that the von Neumann algebra is the…

math.OA2021

On the von Neumann algebra of class functions on a compact quantum group

Jacek Krajczok, Mateusz Wasilewski

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 quantu…

math.OA2020

Compact quantum group structures on type-I -algebras

Alexandru Chirvasitu, Jacek Krajczok, Piotr M. Sołtan

We prove a number of results having to do with equipping type-I -algebras with compact quantum group structures, the two main ones being that such a compact quantum g…

math.QA2020

Modular properties of type I locally compact quantum groups

Jacek Krajczok

The following paper is devoted to the study of type I locally compact quantum groups. We show how various operators related to the modular theory of the Haar integrals on $\mathbb{…

math.OA2020

The quantum disk is not a quantum group

Jacek Krajczok, Piotr M. Sołtan

We show that the quantum disk, i.e. the quantum space corresponding to the Toeplitz C*-algebra does not admit any compact quantum group structure. We prove that if such a structure…

math.OA2020★ 2 cited

Coamenability of type I locally compact quantum groups

Jacek Krajczok

We establish two conditions equivalent to coamenability for type I locally compact quantum groups. The first condition is concerned with the spectra of certain convolution operator…

math.QA2018

Symmetry of eigenvalues of operators associated with representations of compact quantum groups

Jacek Krajczok

We ask the question whether for a given unitary representation the associated operator has spectrum invariant under inversion -- in th…

math.QA2017★ 1 cited

Compact quantum groups with representations of bounded degree

Jacek Krajczok, Piotr M. Sołtan

We show that a compact quantum group all whose irreducible representations have dimension bounded by a fixed constant must be of Kac type, in other words, its Haar measure is a tra…

math.OA2016

Center of the algebra of functions on the quantum group and related topics

Jacek Krajczok, Piotr M. Sołtan

The center of the algebra of continuous functions on the quantum group is determined as well as centers of other related algebras. Several other results concerning this q…