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Mesures spectrales de Walsh associées à certaines suites arithmétiques

Jean Coquet (1985)

Annales de l'institut Fourier

On associe à certaines suites g de nombres complexes une mesure borélienne positive μ g sur le tore dont la transformée de Fourier-Walsh est une suite de moyennes liées à g . La nature de μ g (discrète, continue) est discutée dans quelques cas : suites presque-périodiques et certaines suites arithmétiques.

Necessary condition for measures which are ( L q , L p ) multipliers

Bérenger Akon Kpata, Ibrahim Fofana, Konin Koua (2009)

Annales mathématiques Blaise Pascal

Let G be a locally compact group and ρ the left Haar measure on G . Given a non-negative Radon measure μ , we establish a necessary condition on the pairs q , p for which μ is a multiplier from L q G , ρ to L p G , ρ . Applied to n , our result is stronger than the necessary condition established by Oberlin in [14] and is closely related to a class of measures defined by Fofana in [7].When G is the circle group, we obtain a generalization of a condition stated by Oberlin [15] and improve on it in some cases.

On Beurling measure algebras

Ross Stokke (2022)

Commentationes Mathematicae Universitatis Carolinae

We show how the measure theory of regular compacted-Borel measures defined on the δ -ring of compacted-Borel subsets of a weighted locally compact group ( G , ω ) provides a compatible framework for defining the corresponding Beurling measure algebra ( G , ω ) , thus filling a gap in the literature.

On certain regularity properties of Haar-null sets

Pandelis Dodos (2004)

Fundamenta Mathematicae

Let X be an abelian Polish group. For every analytic Haar-null set A ⊆ X let T(A) be the set of test measures of A. We show that T(A) is always dense and co-analytic in P(X). We prove that if A is compact then T(A) is G δ dense, while if A is non-meager then T(A) is meager. We also strengthen a result of Solecki and we show that for every analytic Haar-null set A, there exists a Borel Haar-null set B ⊇ A such that T(A)∖ T(B) is meager. Finally, under Martin’s Axiom and the negation of Continuum Hypothesis,...

On concentrated probabilities on non locally compact groups

Wojciech Bartoszek (1996)

Commentationes Mathematicae Universitatis Carolinae

Let G be a Polish group with an invariant metric. We characterize those probability measures μ on G so that there exist a sequence g n G and a compact set A G with   μ * n ( g n A ) 1   for all n .

On continuity of measurable group representations and homomorphisms

Yulia Kuznetsova (2012)

Studia Mathematica

Let G be a locally compact group, and let U be its unitary representation on a Hilbert space H. Endow the space ℒ(H) of bounded linear operators on H with the weak operator topology. We prove that if U is a measurable map from G to ℒ(H) then it is continuous. This result was known before for separable H. We also prove that the following statement is consistent with ZFC: every measurable homomorphism from a locally compact group into any topological group is continuous.

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