Uniqueness theorems for almost analytic functions and their use in approximation theory and in the theory of Toeplitz operators
Unital strongly harmonic commutative Banach algebras
A unital commutative Banach algebra is spectrally separable if for any two distinct non-zero multiplicative linear functionals φ and ψ on it there exist a and b in such that ab = 0 and φ(a)ψ(b) ≠ 0. Spectrally separable algebras are a special subclass of strongly harmonic algebras. We prove that a unital commutative Banach algebra is spectrally separable if there are enough elements in such that the corresponding multiplication operators on have the decomposition property (δ). On the other hand,...
Unitary dilation for polar decompositions of p-hyponormal operators
In this paper, we introduce the angular cutting and the generalized polar symbols of a p-hyponormal operator T in the case where U of the polar decomposition T = U|T| is not unitary and study spectral properties of it.
Unitary equivalence and decompositions of finite systems of closed densely defined operators in Hilbert spaces [Book]
Unitary Mappings Between Multiresolution Analyses of L... (R) and a Parametrization of Low-Pass Filters.
Unitary parts of generalized Hankel operators
Universal interpolating sequences on some function spaces
Let be the Hilbert space with reproducing kernel . This paper characterizes some sufficient conditions for a sequence to be a universal interpolating sequence for .
Universal Jamison spaces and Jamison sequences for C₀-semigroups
An increasing sequence of positive integers is said to be a Jamison sequence if for every separable complex Banach space X and every T ∈ ℬ(X) which is partially power-bounded with respect to , the set is at most countable. We prove that for every separable infinite-dimensional complex Banach space X which admits an unconditional Schauder decomposition, and for any sequence which is not a Jamison sequence, there exists T ∈ ℬ(X) which is partially power-bounded with respect to and has the...
Universal Taylor series with maximal cluster sets.
Universality of derivative and antiderivative operators with holomorphic coefficients
We prove some conditions on a sequence of functions and on a complex domain for the existence of universal functions with respect to sequences of certain derivative and antiderivative operators related to them. Conditions for the equicontinuity of those families of operators are also studied. The conditions depend upon the "size" of the domain and functions. Some earlier results about multiplicative complex sequences are extended.
Universally divergent Fourier series via Landau's extremal functions
We prove the existence of functions , the Fourier series of which being universally divergent on countable subsets of . The proof is based on a uniform estimate of the Taylor polynomials of Landau’s extremal functions on .
Universally weakly inner one-parameter automorphism groups of seperable C*-algebras, II.
Upper and lower bounds for regularized determinants.