Les applications continues du cercle dans ont des séries de Fourier intéressantes : le théorème établi ici dit que si les coefficients de Fourier sont de carré sommable avec certains poids pour , il en est de même pour . C’est encore vrai pour , mais faux pour les applications mesurables bornées.
Soit , algèbre de convolution des mesures de Radon bornées sur le groupe abélien localement compact . Pour que soit fermé dans (ou, ce qui revient au même, pour que soit fermé), il faut et il suffit que soit la convolution d’une mesure inversible et d’une mesure idempotente.
We give a sufficient condition for a non-negative random variable to be of Pareto type by investigating the Laplace-Stieltjes transform of the cumulative distribution function. We focus on the relation between the singularity at the real point of the axis of convergence and the asymptotic decay of the tail probability. For the proof of our theorems, we apply Graham-Vaaler’s complex Tauberian theorem. As an application of our theorems, we consider the asymptotic decay of the stationary distribution...
We extend to the setting of Dirichlet series previous results of H. Bohr for Taylor series in one variable, themselves generalized by V. I. Paulsen, G. Popescu and D. Singh or extended to several variables by L. Aizenberg, R. P. Boas and D. Khavinson. We show in particular that, if with , then and even slightly better, and , C being an absolute constant.
The well-known Bohr-Pál theorem asserts that for every continuous real-valued function f on the circle there exists a change of variable, i.e., a homeomorphism h of onto itself, such that the Fourier series of the superposition f ∘ h converges uniformly. Subsequent improvements of this result imply that actually there exists a homeomorphism that brings f into the Sobolev space . This refined version of the Bohr-Pál theorem does not extend to complex-valued functions. We show that if α < 1/2,...