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We provide some background on the category of classifiable $\mathrm{C}^*$-algebras, whose objects are infinite-dimensional, simple, separable, unital $\mathrm{C}^*$-algebras that have finite nuclear dimension and satisfy the universal…

Operator Algebras · Mathematics 2025-12-09 Bhishan Jacelon

We study the simplicity of $C^{*}$-algebras built from group actions. For a faithful isometric action of a group $G$ on a countable metric space $X$, we use the associated action representation on $\ell^2(X)$ to define the action-based…

Operator Algebras · Mathematics 2026-05-04 Tianyi Lou

Abnormal behavior detection in surveillance video is a pivotal part of the intelligent city. Most existing methods only consider how to detect anomalies, with less considering to explain the reason of the anomalies. We investigate an…

Computer Vision and Pattern Recognition · Computer Science 2021-07-30 Luchuan Song , Bin Liu , Huihui Zhu , Qi Chu , Nenghai Yu

Partial actions of groups on C*-algebras and the closely related actions and coactions of Hopf algebras received much attention over the last decades. They arise naturally as restrictions of their global counterparts to non-invariant…

Operator Algebras · Mathematics 2018-11-14 Franziska Kraken , Paula Quast , Thomas Timmermann

We classify real or complex finite-dimensional $C^*$-algebras and their underlying fields from the properties of Birkhoff-James orthogonality. Application to strong Birkhoff-James orthogonality preservers is also given.

Operator Algebras · Mathematics 2024-11-26 Bojan Kuzma , Sushil Singla

This paper develops novel conformal prediction methods for classification tasks that can automatically adapt to random label contamination in the calibration sample, leading to more informative prediction sets with stronger coverage…

Methodology · Statistics 2024-02-23 Matteo Sesia , Y. X. Rachel Wang , Xin Tong

We show that for a large class of actions $\Gamma \curvearrowright \mathcal{A}$ of $C^*$-simple groups $\Gamma$ on unital $C^*$-algebras $\mathcal{A}$, including any non-faithful action of a hyperbolic group with trivial amenable radical,…

Operator Algebras · Mathematics 2019-02-08 Tattwamasi Amrutam

This paper deals with the binary classification task when the target class has the lower probability of occurrence. In such situation, it is not possible to build a powerful classifier by using standard methods such as logistic regression,…

Machine Learning · Statistics 2015-02-26 Cheikh Ndour , Aliou Diop , Simplice Dossou-Gbété

This paper studies the problem of detecting anomalous graphs using a machine learning model trained on only normal graphs, which has many applications in molecule, biology, and social network data analysis. We present a self-discriminative…

Machine Learning · Computer Science 2023-10-11 Jinyu Cai , Yunhe Zhang , Jicong Fan

We show the uniqueness of minimal actions of a compact Kac algebra with amenable dual on the AFD factor of type II$_1$. This particularly implies the uniqueness of minimal actions of a compact group. Our main tools are a Rohlin type…

Operator Algebras · Mathematics 2009-11-11 Toshihiko Masuda , Reiji Tomatsu

We study the classification of group actions on C*-algebras up to equivariant KK-equivalence. We show that any group action is equivariantly KK-equivalent to an action on a simple, purely infinite C*-algebra. We show that a conjecture of…

K-Theory and Homology · Mathematics 2021-08-25 Ralf Meyer

There is a growing need for machine learning-based anomaly detection strategies to broaden the search for Beyond-the-Standard-Model (BSM) physics at the Large Hadron Collider (LHC) and elsewhere. The first step of any anomaly detection…

High Energy Physics - Phenomenology · Physics 2023-01-18 Gregor Kasieczka , Radha Mastandrea , Vinicius Mikuni , Benjamin Nachman , Mariel Pettee , David Shih

The success of deep learning research has catapulted deep models into production systems that our society is becoming increasingly dependent on, especially in the image and video domains. However, recent work has shown that these largely…

Computer Vision and Pattern Recognition · Computer Science 2018-11-30 Nathan Inkawhich , Matthew Inkawhich , Yiran Chen , Hai Li

This paper develops some general results about actions of finite groups on (infinite) abelian groups in the finite Morley rank category. They are linked to a range of problems on groups of finite Morley rank discussed in [16]. Crucially,…

Group Theory · Mathematics 2024-07-24 Alexandre Borovik

We study compact group actions with finite Rokhlin dimension, particularly in relation to crossed products. For example, we characterize the duals of such actions, generalizing previous partial results for the Rokhlin property. As an…

Operator Algebras · Mathematics 2020-10-01 Eusebio Gardella , Ilan Hirshberg , Luis Santiago

We develop a new structural result for cohomogeneity one actions on (not necessarily irreducible) symmetric spaces of noncompact type and arbitrary rank. We apply this result to classify cohomogeneity one actions on SL(n,R)/SO(n), n>1, up…

Differential Geometry · Mathematics 2026-02-25 Jose Carlos Diaz-Ramos , Miguel Dominguez-Vazquez , Tomas Otero

We have developed an unsupervised anomalous sound detection method for machine condition monitoring that utilizes an auxiliary task -- detecting when the target machine is active. First, we train a model that detects machine activity by…

Audio and Speech Processing · Electrical Eng. & Systems 2022-04-18 Tomoya Nishida , Kota Dohi , Takashi Endo , Masaaki Yamamoto , Yohei Kawaguchi

We study (von Neumann) regular $^*$-subalgebras of $B(H)$, which we call R$^*$-algebras. The class of R$^*$-algebras coincides with that of "E$^*$-algebras that are pre-C$^*$-algebras" in the sense of Z. Sz\H{u}cs and B. Tak\'acs. We give…

Operator Algebras · Mathematics 2022-03-23 Michiya Mori

We investigate the transfer of the Cohen-Macaulay property from a commutative ring to a subring of invariants under the action of a finite group. Our point of view is ring theoretic and not a priori tailored to a particular type of group…

Commutative Algebra · Mathematics 2007-05-23 Martin Lorenz , Jawahar Pathak

Network operators are generally aware of common attack vectors that they defend against. For most networks the vast majority of traffic is legitimate. However new attack vectors are continually designed and attempted by bad actors which…

Machine Learning · Computer Science 2019-04-03 Amir Ziai