English

On the sum between a closable operator $T$ and a $T$-bounded operator

Functional Analysis 2014-09-22 v1

Abstract

We provide several perturbation theorems regarding closable operators on a real or complex Hilbert space. In particular we extend some classical results due to Hess--Kato, Kato--Rellich and W\"ust. Our approach involves ranges of matrix operators of the form ( ⁣ ⁣IA ⁣ ⁣ ⁣ ⁣BI ⁣ ⁣)\left(\begin{array}{cc}\!\! I & A\!\!\\ \!\! -B& I\!\!\end{array}\right).

Keywords

Cite

@article{arxiv.1409.5711,
  title  = {On the sum between a closable operator $T$ and a $T$-bounded operator},
  author = {Dan Popovici and Zoltán Sebestyén and Zsigmond Tarcsay},
  journal= {arXiv preprint arXiv:1409.5711},
  year   = {2014}
}
R2 v1 2026-06-22T06:01:03.476Z