Acta mathematica scientia,Series A ›› 2026, Vol. 46 ›› Issue (3): 929-938.

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The Jeribi Essential Spectrum of $2\times 2$ Upper Triangular Block Operator Matrices

Huifang Shi, Deyu Wu*()   

  1. School of Mathematical Sciences, Inner Mongolia University, Hohhot 010021
  • Received:2025-04-08 Revised:2025-06-27 Online:2026-06-26 Published:2026-06-16
  • Contact: Deyu Wu E-mail:3355679774@qq.com
  • Supported by:
    NSFC(12561022);NSFIM(2023MS01019);NSFIM(2022ZD05);Doctoral Program of Hohhot Minzu College(MZXYBS202307)

Abstract:

Let $X$ be a complex infinite dimensional Banach space. In this paper, we mainly study the $2\times 2$ upper triangular block operator matrix $T=\left[\begin{array}{cc}A & B \\0 & D\end{array}\right]$ on $X\times X$. By using the Jeribi essential spectrum of entries $A$ and $D$ to characterize the Jeribi essential spectrum of operator matrix $T$. Some sufficient conditions for the relationship $\hat{\sigma_{J}}(T)=\sigma_{J}(A)\cup\sigma_{J}(D)$ hold are given. Also, the relationship between the Jeribi essential spectrum of operator matrix $T$ and other spectrum of $A,D$ are given.

Key words: Banach space, upper triangular block operator matrix, Jeribi essential spectrum, Fredholm operator.

CLC Number: 

  • O175.3
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