Integral Equations and Operator Theory

, Volume 83, Issue 1, pp 73–94 | Cite as

Representation Theorems for Indefinite Quadratic Forms Without Spectral Gap

  • Stephan Schmitz


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).

Mathematics Subject Classification

Primary 47A07 47A67 Secondary 15A63 47A55 


Indefinite quadratic form Representation theorem 


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Copyright information

© Springer Basel 2015

Authors and Affiliations

  1. 1.FB 08 - Institut für MathematikJohannes Gutenberg-Universität MainzMainzGermany

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