Some remarks on eigenfunction expansions for Schrödinger operators with non-local potentials.
Some Remarks on Inequalities of Landau and Kolmogorov.
Some remarks on perturbation classes of semi-Fredholm and Fredholm operators.
Some remarks on the asymptotic behaviour of the iterates of a bounded linear operator
We discuss the problem of characterizing the possible asymptotic behaviour of the norm of the iterates of a bounded linear operator between two Banach spaces. In particular, given an increasing sequence of positive numbers tending to infinity, we construct Banach spaces such that the norm of the iterates of a suitable multiplication operator between these spaces assumes (or exceeds) the values of this sequence.
Some remarks on the invariant subspace problem for hyponormal operators.
Some remarks on the spectra and numerical range
Some remarks on the surjectivity spectrum of linear operators
Some Remarks on Transmutation, Scattering Theory, and Special Functions.
Some remarks to coincidence theory
Some results about Beurling algebras with applications to operator theory
We prove that certain maximal ideals in Beurling algebras on the unit disc have approximate identities, and show the existence of functions with certain properties in these maximal ideals. We then use these results to prove that if T is a bounded operator on a Banach space X satisfying as n → ∞ for some β ≥ 0, then diverges for every x ∈ X such that .
Some results on dominant operators.
Some results on operator means and shorted operators.
Some reverses of the Jensen inequality for functions of selfadjoint operators in Hilbert spaces.
Some spectral inclusions on D-commuting systems.
Some spectral inequalities involving generalized scalar operators
In 1971, Allan Sinclair proved that for a hermitian element h of a Banach algebra and λ complex we have ∥λ + h∥ = r(λ + h), where r denotes the spectral radius. Using Levin's subordination theory for entire functions of exponential type, we extend this result locally to a much larger class of generalized spectral operators. This fundamental result improves many earlier results due to Gelfand, Hille, Colojoară-Foiaş, Vidav, Dowson, Dowson-Gillespie-Spain, Crabb-Spain, I. & V. Istrăţescu, Barnes,...
Some summation formulae in commutative Leibniz algebras with logarithms
Some theorems on the stability of numerical processes
Nell’articolo si dimostrano alcuni teoremi sulla stabilità dei processi numerici di Ritz e della collocazione in rapporto agli errori di «distorsione».
Some variants of Anderson's inequality in -classes.
Some vector inequalities for continuous functions of self-adjoint operators in Hilbert spaces.
Some versions of Anderson's and Maher's inequalities. I.