Displaying similar documents to “Sets with doubleton sections, good sets and ergodic theory”

Coordinatewise decomposition, Borel cohomology, and invariant measures

Benjamin D. Miller (2006)

Fundamenta Mathematicae

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Given Polish spaces X and Y and a Borel set S ⊆ X × Y with countable sections, we describe the circumstances under which a Borel function f: S → ℝ is of the form f(x,y) = u(x) + v(y), where u: X → ℝ and v: Y → ℝ are Borel. This turns out to be a special case of the problem of determining whether a real-valued Borel cocycle on a countable Borel equivalence relation is a coboundary. We use several Glimm-Effros style dichotomies to give a solution to this problem in terms of certain σ-finite...

Finiteness of Ergodic Unitarily Invariant Measures on Spaces of Infinite Matrices

Alexander I. Bufetov (2014)

Annales de l’institut Fourier

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The main result of this note, Theorem 1.3, is the following: a Borel measure on the space of infinite Hermitian matrices, that is invariant and ergodic under the action of the infinite unitary group and that admits well-defined projections onto the quotient space of “corners" of finite size, must be finite. A similar result, Theorem 1.1, is also established for unitarily invariant measures on the space of all infinite complex matrices. These results imply that the infinite Hua-Pickrell...

On uniqueness of G-measures and g-measures

Ai Fan (1996)

Studia Mathematica

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We give a simple proof of the sufficiency of a log-lipschitzian condition for the uniqueness of G-measures and g-measures which were studied by G. Brown, A. H. Dooley and M. Keane. In the opposite direction, we show that the lipschitzian condition together with positivity is not sufficient. In the special case where the defining function depends only upon two coordinates, we find a necessary and sufficient condition. The special case of Riesz products is discussed and the Hausdorff dimension...

Shift invariant measures and simple spectrum

A. Kłopotowski, M. Nadkarni (2000)

Colloquium Mathematicae

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We consider some descriptive properties of supports of shift invariant measures on ℂ ℤ under the assumption that the closed linear span (in L 2 ) of the co-ordinate functions on ℂ ℤ is all of L 2 .

The product-decomposability of probability measures on Abelian metrizable groups

Krakowiak Wiesław

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Introduction.............................................................5I. Preliminaries.........................................................6   1.1. Semigroups........................................7   1.2. Algebraic groups..................................7   1.3. Additive operators in Abelian groups and linear operators in linear spaces................................8   1.4. Abelian metrizable groups........................10   1.5. Locally compact Abelian groups...................13   1.6....