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Equivalence relations can be defined on Gauss phrases using combinatorial moves. In this paper we consider two closely related equivalence relations on Gauss phrases, homotopy and open homotopy. In particular, in each case, we define a new…

Geometric Topology · Mathematics 2009-01-31 Andrew Gibson

We study properties of the Weyl pseudometric associated with an action of a countable amenable group on a compact metric space. We prove that the topological entropy and the number of minimal subsets of the closure of an orbit are both…

Dynamical Systems · Mathematics 2018-08-01 Martha Łącka , Marta Straszak

We introduce a notion of quasi-weak equivalences associated with weak-equivalences in an exact category. It gives us a delooping for (idempotent complete) exact categories and a condition that the negative $K$-group of an exact category…

K-Theory and Homology · Mathematics 2010-09-24 Toshiro Hiranouchi , Satoshi Mochizuki

We study polar actions with horizontal sections on the total space of certain principal bundles $G/K\to G/H$ with base a symmetric space of compact type. We classify such actions up to orbit equivalence in many cases. In particular, we…

Differential Geometry · Mathematics 2011-03-07 Marco Mucha

The transverse group associated to some continuous quantum measuring processes is analyzed in the presence of nonvanishing gravitational fields. This is done considering, as an exmaple, the case of a particle whose coordinates are being…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Abel Camacho Quintana

Let $X$ be a locally compact zero-dimensional space, let $S$ be an equicontinuous set of homeomorphisms such that $1 \in S = S^{-1}$, and suppose that $\overline{Gx}$ is compact for each $x \in X$, where $G = \langle S \rangle$. We show in…

Group Theory · Mathematics 2018-07-25 Colin D. Reid

We introduce an algebraic invariant for aperiodic inclusions of probability measure preserving equivalence relations. We use this invariant to prove that every stable orbit equivalence between free pmp actions of direct products of…

Group Theory · Mathematics 2025-07-17 Cyril Houdayer , Sven Raum

In the first part of the paper, we introduce notions of asymptotic continuous orbit equivalence and asymptotic conjugacy in Smale spaces and characterize them in terms of their asymptotic Ruelle algebras with their dual actions. In the…

Operator Algebras · Mathematics 2018-07-27 Kengo Matsumoto

We study actions by lattices in higher-rank (semi)simple Lie groups on compact manifolds. By classifying certain measures invariant under a related higher-rank abelian action (the diagonal action on the suspension space) we deduce a number…

Dynamical Systems · Mathematics 2024-06-04 Aaron Brown , Federico Rodriguez Hertz , Zhiren Wang

Rigid actions have zero Rokhlin entropy and nonpositive sofic entropy. Because rigidity is a stable orbit-equivalence invariant, this provides the first example of an essentially free, ergodic, probability-measure-preserving action of the…

Dynamical Systems · Mathematics 2015-07-31 Lewis Bowen

We use a novel type of epistemic logic, employing comparative knowledge assertions, to analyze the relative epistemic powers of individuals or groups of agents. Such comparative assertions can express that a group has the potential to…

Logic in Computer Science · Computer Science 2025-12-09 Baltag Alexandru , Smets Sonja

We prove an uncertainty relation, which imposes a bound on any joint measurement of position and momentum. It is of the form $(\Delta P)(\Delta Q)\geq C\hbar$, where the `uncertainties' quantify the difference between the marginals of the…

Quantum Physics · Physics 2016-09-08 R. F. Werner

We consider the problems of measurable isomorphisms and joinings, measurable centralizers and quotients for certain classes of ergodic group actions on infinite measure spaces. Our main focus is on systems of algebraic origin: actions of…

Dynamical Systems · Mathematics 2007-05-23 Alex Furman

We show that orbit equivalence relations arising from essentially free ergodic probability measure preserving actions of Zariski dense discrete subgroups of simple algebraic groups are strongly prime. As a consequence, we prove the…

Dynamical Systems · Mathematics 2025-07-17 Daniel Drimbe , Cyril Houdayer

We give a new proof of a theorem of Giordano, Putnam and Skau characterizing orbit equivalence of minimal homeomorphisms of the Cantor space in terms of their sets of invariant Borel probability measures. The proof is based on a…

Dynamical Systems · Mathematics 2023-02-21 Julien Melleray , Simon Robert

We propose a conjugate logic that can capture the behavior of quantum and quantum-like systems. The proposal is similar to the more generic concept of epistemic logic: it encodes knowledge or perhaps more correctly, predictions about…

Quantum Physics · Physics 2024-01-10 Niklas Johansson , Felix Huber , Jan-Åke Larsson

The goals of this paper are twofold. First, we generalize the result of Gaboriau and Lyons [GL07] to the setting of von Neumann's problem for equivalence relations, proving that for any non-amenable ergodic probability measure preserving…

Dynamical Systems · Mathematics 2017-10-10 Lewis Bowen , Daniel Hoff , Adrian Ioana

We establish criteria for turbulence in certain spaces of C*-algebra representations and apply this to the problem of nonclassifiability by countable structures for group actions on a standard atomless probability space (X,\mu) and on the…

Operator Algebras · Mathematics 2014-02-26 David Kerr , Hanfeng Li , Mikael Pichot

We analyze various uncertainty measures for spatial diffusion processes. In this manifestly non-quantum setting, we focus on the existence issue of complementary pairs whose joint dispersion measure has strictly positive lower bound.

Statistical Mechanics · Physics 2009-11-13 Piotr Garbaczewski

The aim of this work is to provide a unified framework for ordinal representations of uncertainty lying at the crosswords between possibility and probability theories. Such confidence relations between events are commonly found in monotonic…

Artificial Intelligence · Computer Science 2012-08-07 Didier Dubois , Helene Fargier