Colacunary sequences in L-spaces
Colombeau product of de Rham's currents coincides with generalized Itano one. Sufficient conditions are found under which it is diffeomorphism invariant.
Let M₁ and M₂ be N-functions. We establish some combinatorial inequalities and show that the product spaces are uniformly isomorphic to subspaces of L₁ if M₁ and M₂ are “separated” by a function , 1 < r < 2.
The main meaning of the common extension for two linear operators is the following: given two vector subspaces G₁ and G₂ in a vector space (respectively an ordered vector space) E, a Dedekind complete ordered vector space F and two (positive) linear operators T₁: G₁ → F, T₂: G₂ → F, when does a (positive) linear common extension L of T₁, T₂ exist? First, L will be defined on span(G₁ ∪ G₂). In other results, formulated in the line of the Hahn-Banach extension theorem, the common...
Let μ and λ be bounded positive singular measures on the unit circle such that μ ⊥ λ. It is proved that there exist positive measures μ₀ and λ₀ such that μ₀ ∼ μ, λ₀ ∼ λ, and , where is the associated singular inner function of μ. Let be the common zeros of equivalent singular inner functions of . Then (μ) ≠ ∅ and (μ) ∩ (λ) = ∅. It follows that μ ≪ λ if and only if (μ) ⊂ (λ). Hence (μ) is the set in the maximal ideal space of which relates naturally to the set of measures equivalent to μ....
We study connected components of a common zero set of equivalent singular inner functions in the maximal ideal space of the Banach algebra of bounded analytic functions on the open unit disk. To study topological properties of zero sets of inner functions, we give a new type of factorization theorem for inner functions.
We study a certain operator of multiplication by monomials in the weighted Bergman space both in the unit disk of the complex plane and in the polydisk of the -dimensional complex plane. Characterization of the commutant of such operators is given.
This paper characterizes the commutant of certain multiplication operators on Hilbert spaces of analytic functions. Let be the operator of multiplication by z on the underlying Hilbert space. We give sufficient conditions for an operator essentially commuting with A and commuting with for some n>1 to be the operator of multiplication by an analytic symbol. This extends a result of Shields and Wallen.