Scholarlink

<p>In this paper, we give some properties for the so-called <i>ε</i>-pseudo weakly demicompact linear operators acting on Banach spaces with respect to a closed linear operator. Some sufficient conditions on the entries of an unbounded 2 × 2 block operator matrix <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\cal L}_0\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msub> <mrow> <mi mathvariant="script">L</mi> </mrow> <mn>0</mn> </msub> </math></EquationSource> </InlineEquation> ensuring its <i>ε</i>-pseudo weak demicompactness are provided. In addition, we apply the obtained results to discuss the incidence of some perturbation results on the behavior of essential pseudospectra of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\cal L}_0\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msub> <mrow> <mi mathvariant="script">L</mi> </mrow> <mn>0</mn> </msub> </math></EquationSource> </InlineEquation>. The results are formulated in terms of some denseness conditions on the topological dual space.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Pseudo weak-demicompactness for 2 × 2 block operator matrices and some perturbation properties

  • 期刊论文

  • 发表日期：

    2025年12月1日

查看全文
  • Ines Chtourou,
  • Bilel Krichen

摘要

In this paper, we give some properties for the so-called ε-pseudo weakly demicompact linear operators acting on Banach spaces with respect to a closed linear operator. Some sufficient conditions on the entries of an unbounded 2 × 2 block operator matrix \({\cal L}_0\) L 0 ensuring its ε-pseudo weak demicompactness are provided. In addition, we apply the obtained results to discuss the incidence of some perturbation results on the behavior of essential pseudospectra of \({\cal L}_0\) L 0 . The results are formulated in terms of some denseness conditions on the topological dual space.