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We characterise the simplicity of metric ultraproducts of a family of metric groups. We also present several new examples of simple groups, such as metric ultraproducts of finite and infinite symmetric groups, linear groups, and interval…

Group Theory · Mathematics 2024-09-30 Jakub Gismatullin , Krzysztof Majcher , Martin Ziegler

The target of this article is to discuss the concept of \textit{commuting probability} of finite groups which, in short, is a probabilistic measure of how abelian our group is. We shall compute the value of commuting probability for many…

Group Theory · Mathematics 2023-08-02 Snehinh Sen

Given a finite collection of estimators or classifiers, we study the problem of model selection type aggregation, that is, we construct a new estimator or classifier, called aggregate, which is nearly as good as the best among them with…

Statistics Theory · Mathematics 2008-11-10 A. Juditsky , P. Rigollet , A. B. Tsybakov

We study uniform and non-uniform model sets in arbitrary locally compact second countable (lcsc) groups, which provide a natural generalization of uniform model sets in locally compact abelian groups as defined by Meyer and used as…

Dynamical Systems · Mathematics 2020-02-14 Michael Björklund , Tobias Hartnick , Felix Pogorzelski

In the context of averaging method, we describe a reconstruction of invariant connection-dependent Poisson structures from canonical actions of compact Lie groups on fibered phase spaces. Some symmetry properties of Wong's type equations…

Differential Geometry · Mathematics 2023-12-18 M. Avendaño-Camacho , J. C. Ruíz-Pantaleón , Yu. Vorobiev

We identify a recently proposed shifting operation on classical phase space as a gauge transformation for statistical mechanical microstates. The infinitesimal generators of the continuous gauge group form a non-commutative Lie algebra,…

Statistical Mechanics · Physics 2024-11-20 Johanna Müller , Sophie Hermann , Florian Sammüller , Matthias Schmidt

We use the notion of the principal three-dimensional subgroup of a simple Lie group to identify certain special subspaces of the Lie algebra and address the question of whether these are calibrated for invariant forms on the group.

Differential Geometry · Mathematics 2022-01-19 Nigel Hitchin

This paper is a study of the Lie groups of point symmetries admitted by a system describing a non-stationary planar flow of an ideal plastic material. For several types of forces involved in the system, the infinitesimal generators which…

Mathematical Physics · Physics 2015-06-23 Vincent Lamothe

Recently, there has been great interest in estimating the conditional average treatment effect using flexible machine learning methods. However, in practice, investigators often have working hypotheses about effect heterogeneity across…

Methodology · Statistics 2023-09-13 Chan Park , Hyunseung Kang

Silhouette coefficient is an established internal clustering evaluation measure that produces a score per data point, assessing the quality of its clustering assignment. To assess the quality of the clustering of the whole dataset, the…

Machine Learning · Computer Science 2024-06-25 John Pavlopoulos , Georgios Vardakas , Aristidis Likas

Grouping structures arise naturally in many statistical modeling problems. Several methods have been proposed for variable selection that respect grouping structure in variables. Examples include the group LASSO and several concave group…

Statistics Theory · Mathematics 2013-01-07 Jian Huang , Patrick Breheny , Shuangge Ma

In the context of the variational bi-complex, we re-explain that irreducible gauge systems define a particular example of a Lie algebroid. This is used to review some recent and not so recent results on gauge, global and asymptotic…

Mathematical Physics · Physics 2015-05-20 Glenn Barnich

The rapid development of derandomization theory, which is a fundamental area in theoretical computer science, has recently led to many surprising applications outside its initial intention. We will review some recent such developments…

Information Theory · Computer Science 2015-03-17 Mahdi Cheraghchi

An inclusion of observable nets satisfying duality induces an inclusion of canonical field nets. Any Bose net intermediate between the observable net and the field net and satisfying duality is the fixed-point net of the field net under a…

Operator Algebras · Mathematics 2009-10-31 Roberto Conti , Sergio Doplicher , John E. Roberts

Group fairness definitions such as Demographic Parity and Equal Opportunity make assumptions about the underlying decision-problem that restrict them to classification problems. Prior work has translated these definitions to other machine…

Machine Learning · Computer Science 2023-11-28 Jack Blandin , Ian Kash

We consider gauge theories on noncommutative euclidean space . In particular, we discuss the structure of gauge group following standard mathematical definitions and using the ideas of hep-th/0102182.

High Energy Physics - Theory · Physics 2016-11-23 Albert Schwarz

In this note we study countable subgroups of the full group of a measure preserving equivalence relation. We provide various constraints on the group structure, the nature of the action, and on the measure of fixed point sets, that imply…

Group Theory · Mathematics 2023-09-27 Vadim Alekseev , Alessandro Carderi , Andreas Thom , Robin Tucker-Drob

This survey contains a selection of topics unified by the concept of positive semi-definiteness (of matrices or kernels), reflecting natural constraints imposed on discrete data (graphs or networks) or continuous objects (probability or…

Classical Analysis and ODEs · Mathematics 2019-11-13 Alexander Belton , Dominique Guillot , Apoorva Khare , Mihai Putinar

In many situations it could be interesting to ascertain whether nonparametric regression curves can be grouped, especially when confronted with a considerable number of curves. The proposed testing procedure allows to determine groups with…

Methodology · Statistics 2021-02-02 Nora M. Villanueva , Marta Sestelo , Celestino Ordóñez , Javier Roca-Pardiñas

We revisit a classical question of how individual consumer preferences and incomes shape aggregate behavior. We develop a method that applies to populations with homothetic preferences and reduces the hard problem of aggregation to simply…

Theoretical Economics · Economics 2024-05-13 Fedor Sandomirskiy , Philip Ushchev