On a completion of prehilbertian spaces.
On a question of Mbekhta.
The present paper deals with a question of M. Mbekhta concerning partial isometries on Banach spaces.
On adjoint of an operator on reflexive Banach spaces
On algebraic generation of B(X) by two subalgebras with square zero
On Davis-Kahan-weinberger Extension Theorem
On different products of closed operators.
On Dominating Sequences in the Unit Disc.
On E. Borel's Theorem.
On Farkas-type theorems
On generalized inverses in C*-algebras
We investigate when a C*-algebra element generates a closed ideal, and discuss Moore-Penrose and commuting generalized inverses.
On homomorphisms, open operators and their adjoints.
On Neumann operators.
On nilpotent operators
We give several necessary and sufficient conditions in order that a bounded linear operator on a Banach space be nilpotent. We also discuss three necessary conditions for nilpotency. Furthermore, we construct an infinite family (in one-to-one correspondence with the square-summable sequences of strictly positive real numbers) of nonnilpotent quasinilpotent operators on an infinite-dimensional Hilbert space, all the iterates of each of which have closed range. Each of these operators (as well as...
On operators of Saphar type.
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 quasi-analytic vectors for some classes of operators
On real and complex spectra in some real -algebras and applications.
On representation of linear operators on
On Some Classes of Operators II.
On the axiomatic theory of spectrum II
We give a survey of results concerning various classes of bounded linear operators in a Banach space defined by means of kernels and ranges. We show that many of these classes define a spectrum that satisfies the spectral mapping property.