Approximations- und Eindeutigkeitssatz für Exponentialsysteme mit komplexen Exponenten.
Beweis, dass eine für jeden reellen Werth von x durch eine trigonometrische Reihe gegebene Function f(x) sich nur auf eine einzige Weise in dieser Form darstellen lässt.
Constant Coefficient Differential Operators with Slowly Spreading Solutions.
Contractions à spectre dénombrable et propriétés d'unicité des fermés dénombrables du cercle
On montre que si est une contraction à spectre dénombrable et telle que, pour tout
Distribuzioni funtoriali in una variabile quasi periodiche
Existence of large ε-Kronecker and FZI₀(U) sets in discrete abelian groups
Let G be a compact abelian group with dual group Γ and let ε > 0. A set E ⊂ Γ is a “weak ε-Kronecker set” if for every φ:E → there exists x in the dual of Γ such that |φ(γ)- γ(x)| ≤ ε for all γ ∈ E. When ε < √2, every bounded function on E is known to be the restriction of a Fourier-Stieltjes transform of a discrete measure. (Such sets are called I₀.) We show that for every infinite set E there exists a weak 1-Kronecker subset F, of the same cardinality as E, provided there are not “too many”...
Functions with Time and Frequency Gaps.
Further properties of an extremal set of uniqueness
Lipschitz Classes and Restrictions of Fourier Transforms.
Mean-Periodic Functions Associated with the Jacobi-Dunkl Operator on R
2000 Mathematics Subject Classification: 34K99, 44A15, 44A35, 42A75, 42A63Using a convolution structure on the real line associated with the Jacobi-Dunkl differential-difference operator Λα,β given by: Λα,βf(x) = f'(x) + ((2α + 1) coth x + (2β + 1) tanh x) { ( f(x) − f(−x) ) / 2 }, α ≥ β ≥ −1/2 , we define mean-periodic functions associated with Λα,β. We characterize these functions as an expansion series intervening appropriate elementary functions expressed in terms of the derivatives of the...
On a Theorem of Ingham.
On Menshoff's Set of Multiplicity.
On the localization property of square partial sums for multiple Fourier series
Sets of uniqueness
Singular distributions, dimension of support, and symmetry of Fourier transform
We study the “Fourier symmetry” of measures and distributions on the circle, in relation with the size of their supports. The main results of this paper are:(i) A one-side extension of Frostman’s theorem, which connects the rate of decay of Fourier transform of a distribution with the Hausdorff dimension of its support;(ii) A construction of compacts of “critical” size, which support distributions (even pseudo-functions) with anti-analytic part belonging to .We also give examples of non-symmetry...
Some spherical uniqueness theorems for multiple trigonometric series.
Sur les isomorphismes d'algèbres de restriction
The sizes of the classes of -sets
The class of -sets forms an important subclass of the class of sets of uniqueness for trigonometric series. We investigate the size of this class which is reflected by the family of measures (called polar) annihilating all sets from the class. The main aim of this paper is to answer in the negative a question stated by Lyons, whether the polars of the classes of -sets are the same for all N ∈ ℕ. To prove our result we also present a new description of -sets.
The structure of the -ideal of -porous sets
We show a general method of construction of non--porous sets in complete metric spaces. This method enables us to answer several open questions. We prove that each non--porous Suslin subset of a topologically complete metric space contains a non--porous closed subset. We show also a sufficient condition, which gives that a certain system of compact sets contains a non--porous element. Namely, if we denote the space of all compact subsets of a compact metric space with the Vietoris topology...
Ueber die Ausdehnung eines Satzes aus der Theorie der trigonometrischen Reihen