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Relative residual bounds for eigenvalues in gaps of the essential spectrum

Spectral Theory 2024-07-23 v1 Functional Analysis

Abstract

The relative distance between eigenvalues of the compression of a not necessarily semibounded self-adjoint operator to a closed subspace and some of the eigenvalues of the original operator in a gap of the essential spectrum is considered. It is shown that this distance depends on the maximal angles between pairs of associated subspaces. This generalises results by Drma\v{c} in [Linear Algebra Appl. 244 (1996), 155--163] from matrices to not necessarily (semi)bounded operators.

Keywords

Cite

@article{arxiv.2309.07032,
  title  = {Relative residual bounds for eigenvalues in gaps of the essential spectrum},
  author = {Albrecht Seelmann},
  journal= {arXiv preprint arXiv:2309.07032},
  year   = {2024}
}

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12 pages