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We study random relational structures that are \emph{relatively exchangeable}---that is, whose distributions are invariant under the automorphisms of a reference structure $\mathfrak{M}$. When $\mathfrak{M}$ has {\em trivial definable…

Logic · Mathematics 2015-10-05 Harry Crane , Henry Towsner

We study a compactification of the space of invariant probability measures for a transitive countable Markov shift. We prove that it is affine homeomorphic to the Poulsen simplex. Furthermore, we establish that, depending on a combinatorial…

Dynamical Systems · Mathematics 2025-03-14 Godofredo Iommi , Anibal Velozo

We construct a compact Hausdorff space $K$ such that the space $P(K)$ of Radon probabiblity measures on $K$ considered with the weak$^*$ topology (induced from the space of continuous functions $C(K)$) is countably tight which is a…

Functional Analysis · Mathematics 2023-12-06 Piotr Koszmider , Zdeněk Silber

Given any quasi-countable, in particular any countable inverse semigroup $S$, we introduce a way to equip $S$ with a proper and right subinvariant extended metric. This generalizes the notion of proper, right invariant metrics for discrete…

Operator Algebras · Mathematics 2024-03-01 Yeong Chyuan Chung , Diego Martínez , Nóra Szakács

In this paper we briefly survey the classical problem of understanding which Lie algebras admit a complex structure, put in the broader perspective of almost complex structures with special properties. We focus on the different behavior of…

Differential Geometry · Mathematics 2025-11-14 Lorenzo Sillari , Adriano Tomassini

The Gamma kernel is a projection kernel of the form (A(x)B(y)-B(x)A(y))/(x-y), where A and B are certain functions on the one-dimensional lattice expressed through Euler's Gamma function. The Gamma kernel depends on two continuous…

Probability · Mathematics 2013-03-04 Grigori Olshanski

We show that the algebraic K-theory of semi-valuation rings with stably coherent regular semi-fraction ring satisfies homotopy invariance. Moreover, we show that these rings are regular if their valuation is non-trivial. Thus they yield…

K-Theory and Homology · Mathematics 2025-09-08 Christian Dahlhausen

Let $\mathcal{N}_*$ be the unoriented cobordism algebra, let $G=(\Z_2)^n$ and let $Z_*(G)$ denote the equivariant cobordism algebra of $G$-manifolds with finite stationary point sets. Let $\epsilon_* :Z_*(G) \to \mathcal{N}_*$ be the…

Algebraic Topology · Mathematics 2013-10-24 Samik Basu , Goutam Mukherjee , Swagata Sarkar

We establish the existence and fundamental properties of the equilibrium measure in uniformly quasiregular dynamics. We show that a uniformly quasiregular endomorphism $f$ of degree at least 2 on a closed Riemannian manifold admits an…

Dynamical Systems · Mathematics 2015-05-20 Yûsuke Okuyama , Pekka Pankka

The paper is devoted to the investigation of finite dimensional commutative nilpotent (associative) algebras N over an arbitrary base field of characteristic zero. Due to the lack of a general structure theory for algebras of this type (as…

Commutative Algebra · Mathematics 2011-08-08 Gregor Fels , Wilhelm Kaup

Let $K\subset R^n$ be a compact basic semi-algebraic set. We provide a necessary and sufficient condition (with no a priori bounding parameter) for a real sequence $y=(y_\alpha)$, $\alpha\in N^n$, to have a finite representing Borel measure…

Optimization and Control · Mathematics 2013-07-30 Jean-Bernard Lasserre

The classical de Finetti Theorem classifies the $\mathrm{Sym}(\mathbb N)$-invariant probability measures on $[0,1]^{\mathbb N}$. More precisely it states that those invariant measures are combinations of measures of the form…

Probability · Mathematics 2024-11-05 Colin Jahel , Pierre Perruchaud

We prove that if a Borel probability measure (\mu) on (\T) is invariant under the action of a "large" multiplicative semigroup (lower logarithmic density is positive) and the action of the whole semigroup is ergodic then (\mu) is either…

Dynamical Systems · Mathematics 2008-09-04 Manfred Einsiedler , Alexander Fish

We provide an example of a discrete-time Markov process on the three-dimensional infinite integer lattice with Z_q-invariant Bernoulli-increments which has as local state space the cyclic group Z_q. We show that the system has a unique…

Probability · Mathematics 2014-09-23 Benedikt Jahnel , Christof Kuelske

We study the relationship between the dynamics of the action $\alpha$ of a discrete group $G$ on a von Neumann algebra $M$, and structural properties of the associated crossed product inclusion $L(G) \subseteq M \rtimes_\alpha G$, and its…

Operator Algebras · Mathematics 2024-03-14 Jon Bannon , Jan Cameron , Ionut Chifan , Kunal Mukherjee , Roger Smith , Alan Wiggins

Semi-classically equivalent field theories are related by a quasi-isomorphism between their underlying $L_\infty$-algebras, but such a quasi-isomorphism is not necessarily a homotopy transfer. We demonstrate that all quasi-isomorphisms can…

High Energy Physics - Theory · Physics 2026-01-13 Mehran Jalali Farahani , Christian Saemann , Martin Wolf

A finitely presented, torsion free, abelian-by-cyclic group can always be written as an ascending HNN extension Gamma_M of Z^n, determined by an n x n integer matrix M with det(M) \ne 0. The group Gamma_M is polycyclic if and only if…

Group Theory · Mathematics 2007-05-23 Benson Farb , Lee Mosher

The Lichtenbaum-Quillen conjecture for smooth complex varieties states that algebraic and topological K-theory with finite coefficients become isomorphic in high degrees. We define the "Lichtenbaum-Quillen dimension" of a variety in terms…

Algebraic Geometry · Mathematics 2026-04-14 Nicolas Addington , Elden Elmanto

An almost Abelian group is a non-Abelian Lie group with a codimension 1 Abelian subgroup. This paper investigates invariant Hermitian and K\"{a}hler structures on connected complex almost Abelian groups. We find explicit formulas for the…

Differential Geometry · Mathematics 2023-08-21 Zhirayr Avetisyan , Abigail Brauer , Oderico-Benjamin Buran , Jimmy Morentin , Tianyi Wang

We prove absolute continuity of "high entropy" hyperbolic invariant measures for smooth actions of higher rank abelian groups assuming that there are no proportional Lyapunov exponents. For actions on tori and infranilmanifolds existence of…

Dynamical Systems · Mathematics 2010-01-15 Anatole Katok , Federico Rodriguez Hertz