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Spectral enclosures for a class of block operator matrices

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 Added by Matthias Langer
 Publication date 2019
  fields
and research's language is English




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We prove new spectral enclosures for the non-real spectrum of a class of $2times2$ block operator matrices with self-adjoint operators $A$ and $D$ on the diagonal and operators $B$ and $-B^*$ as off-diagonal entries. One of our main results resembles Gershgorins circle theorem. The enclosures are applied to $J$-frame operators.



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