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We study the spectrum of unbounded -self-adjoint block operator matrices. In particular, we prove enclosures for the spectrum, provide a sucient condition for the spectrum being real and derive variational principles for certain real eigenvalues even in the presence of non-real spectrum. The latter lead to lower and upper bounds and asymptotic estimates for eigenvalues.
Cite this article
Matthias Langer, Michael Strauss, Spectral properties of unbounded -self-adjoint block operator matrices. J. Spectr. Theory 7 (2017), no. 1, pp. 137–190DOI 10.4171/JST/158