Additivity of maps on triangular algebras.
Adjoint characterisations of unbounded weakly compact, weakly completely continuous and unconditionally converging operators
Characterisations are obtained for the following classes of unbounded linear operators between normed spaces: weakly compact, weakly completely continuous, and unconditionally converging operators. Examples of closed unbounded operators belonging to these classes are exhibited. A sufficient condition is obtained for the weak compactness of T' to imply that of T.
Adjoints of composition operators on standard Bergman and Dirichlet spaces on the unit disk.
Adjungiertenbildungen in der Operatortheorie.
Algebra isomorphisms between standard operator algebras
If X and Y are Banach spaces, then subalgebras ⊂ B(X) and ⊂ B(Y), not necessarily unital nor complete, are called standard operator algebras if they contain all finite rank operators on X and Y respectively. The peripheral spectrum of A ∈ is the set of spectral values of A of maximum modulus, and a map φ: → is called peripherally-multiplicative if it satisfies the equation for all A,B ∈ . We show that any peripherally-multiplicative and surjective map φ: → , neither assumed to be linear nor...
Algebraic and essentially algebraic composition operators on C(X).
Algebraic Characterization of Symmetrie Complex Banach Manifolds.
Algebraic isomorphisms and Jordan derivations of 𝒥-subspace lattice algebras
It is shown that every algebraic isomorphism between standard subalgebras of 𝒥-subspace lattice algebras is quasi-spatial and every Jordan derivation of standard subalgebras of 𝒥-subspace lattice algebras is an additive derivation. Also, it is proved that every finite rank operator in a 𝒥-subspace lattice algebra can be written as a finite sum of rank one operators each belonging to that algebra. As an additional result, a multiplicative bijection of a 𝒥-subspace lattice algebra onto an arbitrary...
Algebraic properties of Toeplitz operators on weighted Bergman spaces
We study algebraic properties of two Toeplitz operators on the weighted Bergman space on the unit disk with harmonic symbols. In particular the product property and commutative property are discussed. Further we apply our results to solve a compactness problem of the product of two Hankel operators on the weighted Bergman space on the unit bidisk.
Algebraic spectral subspaces
Algebraic spectral subspaces and automatic continuity
Algebraic sum of unbounded normal operators and the square root problem of Kato
Algebras of quotients with bounded evaluation of a normed semiprime algebra
We deal with the algebras consisting of the quotients that produce bounded evaluation on suitable ideals of the multiplication algebra of a normed semiprime algebra A. These algebras of quotients, which contain A, are subalgebras of the bounded algebras of quotients of A, and they have an algebra seminorm for which the relevant inclusions are continuous. We compute these algebras of quotients for some norm ideals on a Hilbert space H: 1) the algebras of quotients with bounded evaluation of the ideal...
Algebras of singular integral operators on rearrangement-invariant spaces and Nikolski ideals.
Algebras of Toeplitz operators with oscillating symbols.
This paper is devoted to Banach algebras generated by Toeplitz operators with strongly oscillating symbols, that is, with symbols of the form b[eia(x)] where b belongs to some algebra of functions on the unit circle and a is a fixed orientation-preserving homeomorphism of the real line onto itself. We prove the existence of certain interesting homomorphisms and establish conditions for the normal solvability, Fredholmness, and invertibility of operators in these algebras.
Algunas Caracterizaciones De Medidas Espectrales Extendibles.
All nuclear C*-algebras are amenable.
Almost commuting Hermitian matrices.
Almost commuting self-adjoint matrices - a short proof of Huaxin Lin's theorem.
Almost everywhere convergence of generalized ergodic transforms for invertible power-bounded operators in
We show that some results of Gaposhkin about a.e. convergence of series associated to a unitary operator U acting on L²(X,Σ,μ) (μ is a σ-finite measure) may be extended to the case where U is an invertible power-bounded operator acting on , p > 1. The proofs make use of the spectral integration initiated by Berkson-Gillespie and, more specifically, of recent results of the author.