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This article is concerned with measure equivalence and uniform measure equivalence of locally compact, second countable groups. We show that two unimodular, locally compact, second countable groups are measure equivalent if and only if they…

Group Theory · Mathematics 2019-11-19 Juhani Koivisto , David Kyed , Sven Raum

In this paper we generalize Wiener's characterization of continuous measures to compact homogenous manifolds. In particular, we give necessary and sufficient conditions on probability measures on compact semisimple Lie groups and…

Dynamical Systems · Mathematics 2009-01-20 Michael Björklund , Alexander Fish

We obtain a sufficient condition, given a totally disconnected, locally compact group $G$ with a topologically simple monolith $S$, to ensure that $S$ is open in $G$ and abstractly simple.

Group Theory · Mathematics 2019-02-19 Colin D. Reid

We prove that if $K$ is a compact space and the space $P(K\times K)$ of regular probability measures on $K\times K$ has countable tightness in its $weak^*$ topology, then $L_1(\mu)$ is separable for every $\mu\in P(K)$. It has been known…

Functional Analysis · Mathematics 2014-05-13 Grzegorz Plebanek , Damian Sobota

We show the contractibility of spaces of invariant Riemannian metrics of positive scalar curvature on compact connected manifolds of dimension at least two, with and without boundary and equipped with compact Lie group actions. On manifolds…

Differential Geometry · Mathematics 2025-06-23 Christian Baer , Bernhard Hanke

This is a survey on left invariant semi-Riemannian metrics on compact Lie groups.

Differential Geometry · Mathematics 2025-05-19 Abdelghani Zeghib

We extend Langton's valuative criterion for families of coherent algebraic sheaves to a complex analytic set-up. As a consequence we derive a set of sufficient conditions for the compactness of a moduli space of semistable sheaves over a…

Algebraic Geometry · Mathematics 2021-08-30 Matei Toma

We rigorously quantify the improvement in the sample complexity of variational divergence estimations for group-invariant distributions. In the cases of the Wasserstein-1 metric and the Lipschitz-regularized $\alpha$-divergences, the…

Statistics Theory · Mathematics 2024-11-26 Ziyu Chen , Markos A. Katsoulakis , Luc Rey-Bellet , Wei Zhu

We prove a sharp general inequality estimating the distance of two probability measures on a compact Lie group in the Wasserstein metric in terms of their Fourier transforms. We use a generalized form of the Wasserstein metric, related by…

Classical Analysis and ODEs · Mathematics 2021-03-12 Bence Borda

In this paper we continue the study of positive scalar curvature (psc) metrics on a depth-1 Thom-Mather stratified space $M_\Sigma$ with singular stratum $\beta M$ (a closed manifold of positive codimension) and associated link equal to…

Differential Geometry · Mathematics 2021-06-25 Boris Botvinnik , Paolo Piazza , Jonathan Rosenberg

We initiate a quantitative study of measure equivalence (and orbit equivalence) between finitely generated groups, which extends the classical setting of $\mathrm L^p$ measure equivalence. In this paper, our main focus will be on amenable…

Group Theory · Mathematics 2022-04-18 Thiebout Delabie , Juhani Koivisto , François Le Maître , Romain Tessera

We initiate a systematic investigation of group actions on compact medain algebras via the corresponding dynamics on their spaces of measures. We show that a probability measure which is invariant under a natural push forward operation must…

General Topology · Mathematics 2025-03-11 Uri Bader , Aviv Taller

This note provides elementary proofs for necessary density conditions for frames and Riesz sequences in the lattice orbit of a discrete series representation that involve the projective stabiliser of the vector. The presented approach…

Functional Analysis · Mathematics 2025-08-21 Jordy Timo van Velthoven

We present symbolic and numerical methods for computing Poisson brackets on the spaces of measures with positive densities of the plane, the 2-torus, and the 2-sphere. We apply our methods to compute symplectic areas of finite regions for…

Symplectic Geometry · Mathematics 2022-02-15 J. C. Ruíz-Pantaleón , P. Suárez-Serrato

We study smooth actions by lattices in higher-rank simple Lie groups. Assuming one element of the action acts with positive topological entropy, we prove a number of new rigidity results. For lattices in $\mathrm{SL}(n,\mathbb{R})$ acting…

Dynamical Systems · Mathematics 2025-01-24 Aaron Brown , Homin Lee

We describe some sufficient conditions, under which smooth and compactly supported functions are or are not dense in the fractional Sobolev space $W^{s,p}(\Omega)$ for an open, bounded set $\Omega\subset\mathbb{R}^{d}$. The density property…

Analysis of PDEs · Mathematics 2022-12-26 Bartłomiej Dyda , Michał Kijaczko

We introduce actions of a compact Lie group in two regularization processes: in De Rham's approximation process of currents on a smooth manifold by smooth currents, and in a smoothing operator of Riemannian metrics of metric spaces with…

Differential Geometry · Mathematics 2026-02-06 Andrés Ahumada Gómez

We prove that, given any smooth action of a compact quantum group (in the sense of \cite{rigidity}) on a compact smooth manifold satisfying some more natural conditions, one can get a Riemannian structure on the manifold for which the…

Operator Algebras · Mathematics 2015-03-19 Debashish Goswami , Soumalya Joardar

We prove the existence of a quantum isometry groups for new classes of metric spaces: (i) geodesic metrics for compact connected Riemannian manifolds (possibly with boundary) and (ii) metric spaces admitting a uniformly distributed…

Quantum Algebra · Mathematics 2020-10-28 Alexandru Chirvasitu , Debashish Goswami

We study minimax density estimation on the product space $\mathbb{R}^{d_1}\times\mathbb{R}^{d_2}$. We consider $L^p$-risk for probability density functions defined over regularity spaces that allow for different level of smoothness in each…

Statistics Theory · Mathematics 2019-06-18 Galatia Cleanthous , Athanasios G. Georgiadis , Emilio Porcu