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Front d'onde analytique et décomposition microlocale des distributions

Pascal Laubin (1983)

Annales de l'institut Fourier

On étudie en détail une décomposition microlocale analytique de la distribution δ ( x - y ) suivant des distributions singulières en un seul point et dans une seule codirection. Cette décomposition est obtenue à partir d’opérateurs Fourier-Intégraux à phases complexes.On utilise ensuite cet outil pour démontrer le théorème de décomposition du front d’onde analytique des distributions. On établit également des théorèmes concernant la représentation globale des distributions comme sommes de valeurs au bord...

GCD sums from Poisson integrals and systems of dilated functions

Christoph Aistleitner, István Berkes, Kristian Seip (2015)

Journal of the European Mathematical Society

Upper bounds for GCD sums of the form k , = 1 N ( gcd ( n k , n ) ) 2 α ( n k n ) α are established, where ( n k ) 1 k N is any sequence of distinct positive integers and 0 < α 1 ; the estimate for α = 1 / 2 solves in particular a problem of Dyer and Harman from 1986, and the estimates are optimal except possibly for α = 1 / 2 . The method of proof is based on identifying the sum as a certain Poisson integral on a polydisc; as a byproduct, estimates for the largest eigenvalues of the associated GCD matrices are also found. The bounds for such GCD sums are used to establish...

Generalized c -almost periodic type functions in n

M. Kostić (2021)

Archivum Mathematicum

In this paper, we analyze multi-dimensional quasi-asymptotically c -almost periodic functions and their Stepanov generalizations as well as multi-dimensional Weyl c -almost periodic type functions. We also analyze several important subclasses of the class of multi-dimensional quasi-asymptotically c -almost periodic functions and reconsider the notion of semi- c -periodicity in the multi-dimensional setting, working in the general framework of Lebesgue spaces with variable exponent. We provide certain...

Generalized Riesz products produced from orthonormal transforms

Nikolaos Atreas, Antonis Bisbas (2012)

Colloquium Mathematicae

Let p = m k k = 0 p - 1 be a finite set of step functions or real valued trigonometric polynomials on = [0,1) satisfying a certain orthonormality condition. We study multiscale generalized Riesz product measures μ defined as weak-* limits of elements μ N V N ( N ) , where V N are p N -dimensional subspaces of L₂() spanned by an orthonormal set which is produced from dilations and multiplications of elements of p and N V N ¯ = L ( ) . The results involve mutual absolute continuity or singularity of such Riesz products extending previous results on...

Geodesics in the Heisenberg Group

Piotr Hajłasz, Scott Zimmerman (2015)

Analysis and Geometry in Metric Spaces

We provide a new and elementary proof for the structure of geodesics in the Heisenberg group Hn. The proof is based on a new isoperimetric inequality for closed curves in R2n.We also prove that the Carnot- Carathéodory metric is real analytic away from the center of the group.

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