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Representation Theorems for Indefinite Quadratic Forms Without Spectral Gap

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Abstract

The first and second representation theorem for sign-indefinite quadratic forms are extended. We include new cases of unbounded forms associated with operators that do not necessarily have a spectral gap around zero. The kernel of the associated operators is determined for special cases. This extends results by Grubišić et al. (Mathematika 59:169–189, 2013).

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  1. FB 08 - Institut für Mathematik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, 55099, Mainz, Germany

    Stephan Schmitz

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  1. Stephan Schmitz
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Correspondence to Stephan Schmitz.

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Schmitz, S. Representation Theorems for Indefinite Quadratic Forms Without Spectral Gap. Integr. Equ. Oper. Theory 83, 73–94 (2015). https://doi.org/10.1007/s00020-015-2252-3

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  • DOI: https://doi.org/10.1007/s00020-015-2252-3

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