On integral operators with operator-valued kernels.
In this paper the notions of uniformly upper and uniformly lower -estimates for Banach function spaces are introduced. Further, the pair of Banach function spaces is characterized, where and satisfy uniformly a lower -estimate and uniformly an upper -estimate, respectively. The integral operator from into of the form is studied, where , , are prescribed functions under some local integrability conditions, the kernel is non-negative and is assumed to satisfy certain additional...
In the present work, using a formula describing all scalar spectral functions of a Carleman operator of defect indices in the Hilbert space that we obtained in a previous paper, we derive certain results concerning the localization of the spectrum of quasi-selfadjoint extensions of the operator .
On introduit une classe d’opérateurs intégro-différentiels d’ordre infini, à coefficients méromorphes et pour lesquels les séries majorantes sont de type Dirichlet. On établit des résultats algébriques : caractérisation des éléments inversibles, théorèmes de division et de préparation. En les faisant opérer sur divers espaces de séries et de fonctions on obtient des théorèmes d’indices et des résultats de surjectivité. Après transformation de Mellin ces opérateurs permettent d’étudier les “solutions”...
Let Ω= [a, b] × [c, d] and T 1, T 2 be partial integral operators in (Ω): (T 1 f)(x, y) = k 1(x, s, y)f(s, y)ds, (T 2 f)(x, y) = k 2(x, ts, y)f(t, y)dt where k 1 and k 2 are continuous functions on [a, b] × Ω and Ω × [c, d], respectively. In this paper, concepts of determinants and minors of operators E−τT 1, τ ∈ ℂ and E−τT 2, τ ∈ ℂ are introduced as continuous functions on [a, b] and [c, d], respectively. Here E is the identical operator in C(Ω). In addition, Theorems on the spectra of bounded...