The Concept of a -Basis and an Application to the Fredholmness of a Banach-Valued Boundary Value Problem with Oblique Derivative


BILALOV B., Sadigova S., SEZER Y.

Siberian Mathematical Journal, vol.67, no.4, pp.745-755, 2026 (SCI-Expanded, Scopus)

  • Publication Type: Article / Article
  • Volume: 67 Issue: 4
  • Publication Date: 2026
  • Doi Number: 10.1134/s0037446626040014
  • Journal Name: Siberian Mathematical Journal
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, MathSciNet, zbMATH, DIALNET, Academic Search Ultimate (EBSCO), Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
  • Page Numbers: pp.745-755
  • Keywords: 517.957, Banach-valued harmonic function, Bochner space, Fredholmness, problem with oblique derivative
  • Yıldız Technical University Affiliated: Yes

Abstract

We consider the concept of a -basis generated by the tensor product of Banach spaces.We introduce the concept of a -harmonic Banach-valued (-valued) function, where the space under consideration has an involution.Using the fact that the classical system of exponentials forms a -basis for the Bochner space of -valued functions with the UMD property, we define the Hardy class of -harmonic functions in the unit disk.We consider a boundary value problem with oblique derivative in this class and establish a criterion for the Fredholmness and, in particular, the solvability of this problem.Concrete examples are given.