On the approximation of some nonlinear equations.
On the asymptotics of the negative eigenvalues for an axisymmetric idealmagnetohydrodynamic model
On the axiomatic theory of spectrum
There are a number of spectra studied in the literature which do not fit into the axiomatic theory of Żelazko. This paper is an attempt to give an axiomatic theory for these spectra, which, apart from the usual types of spectra, like one-sided, approximate point or essential spectra, include also the local spectra, the Browder spectrum and various versions of the Apostol spectrum (studied under various names, e.g. regular, semiregular or essentially semiregular).
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.
On the Banach principle.
On the canonical development of Parseval formulas for singular differential operators
Per funzioni opportune si ottiene una formula di Parseval per operatori differenziali singolari di tipo dell'operatore radiale di Laplace-Beltrami. è una funzione spettrale generalizzata di tipo Marčenko e può essere rappresentata per mezzo di un certo nucleo della trasmutazione.
On the -characteristic of fractional powers of linear operators
We describe the geometric structure of the -characteristic of fractional powers of bounded or compact linear operators over domains with arbitrary measure. The description builds essentially on the Riesz-Thorin and Marcinkiewicz-Stein-Weiss- Ovchinnikov interpolation theorems, as well as on the Krasnosel’skij-Krejn factorization theorem.
On the characterization of scalar type spectral operators
The paper is concerned with conditions guaranteeing that a bounded operator in a reflexive Banach space is a scalar type spectral operator. The cases where the spectrum of the operator lies on the real axis and on the unit circle are studied separately.
On the Clarkson-McCarthy Inequalities.
On the Closedness of the Sum of Two Closed Operators.
On the commutativity of two projections.
On the compactness of the natural tensor product of compact operators.
On the completeness in three body scattering
On the computation of some quantities in the theory of Fredholm operators
On the convergence and unconditional convergence of series of operators on Banach spaces.
We study Kalton's theorem on the unconditional convergence of series of compact operators and we use some matrix techniques to obtain sufficient conditions, weaker than the previous one, on the convergence and unconditional convergence of series of compact operators.
On the convergence of eigenvalues for mixed formulations
On the convergence of Neumann series for noncompact operators
On the Convergence of Neumann Series in Banach Spaces.
On the convergence of semiiterative methods to the Drazin inverse solution of linear equations in Banach spaces.
On the convergence of sequences of linear operators and adjoint operators