On generalized localizability
On Jensen's inequality for self-adjoint operators in Hilbert space
On Kelley's multiplicity function of an abelian von Neumann algebra
On limits of -norms of an integral operator
A recurrence relation for the computation of the -norms of an Hermitian Fredholm integral operator is derived and an expression giving approximately the number of eigenvalues which in absolute value are equal to the spectral radius is determined. Using the -norms for the approximation of the spectral radius of this operator an a priori and an a posteriori bound for the error are obtained. Some properties of the a posteriori bound are discussed.
On operators with the same spectrum
On product of projections
An operator with infinite dimensional kernel is positive iff it is a positive scalar times a certain product of three projections.
On proper boundary points of the spectrum and complemented eigenspaces.
On quasinormal operators
On scalar type spectral operators, infinite differentiable and Gevrey ultradifferentiable -semigroups.
On some classes of Operators on Hilbert spaces
On Some Operator Inequalities.
On the algebraic structure of the unitary group.
We consider the unitary group U of complex, separable, infinite-dimensional Hilbert space as a discrete group. It is proved that, whenever U acts by isometries on a metric space, every orbit is bounded. Equivalently, U is not the union of a countable chain of proper subgroups, and whenever E ⊆ U generates U, it does so by words of a fixed finite length.
On the Carleman classes of vectors of a scalar type spectral operator.
On the Construction of Iteration Methods for Linear Equations in Banach Spaces by Summation Methods. (Short Communication).
On the Construction of Iteration Methods for Linear Equations in Banach Spaces by Summation Methods.
On the eigenvalues which express antieigenvalues.
On the Fourier cosine—Kontorovich-Lebedev generalized convolution transforms
We deal with several classes of integral transformations of the form where is an operator. In case is the identity operator, we obtain several operator properties on with weights for a generalized operator related to the Fourier cosine and the Kontorovich-Lebedev integral transforms. For a class of differential operators of infinite order, we prove the unitary property of these transforms on and define the inversion formula. Further, for an other class of differential operators of finite...
On the geometric properties of the joint spectrum of a family of self-adjoint operators
On the normality of operators.
On the Normality of the Unbounded Product of Two Normal Operators
Let A and B be two -non necessarily bounded- normal operators. We give new conditions making their product normal. We also generalize a result by Deutsch et al on normal products of matrices.