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On Locally Definite Operators in Krein Spaces

Jonas, Peter

Inst. Mathematik

For selfadjoint operators in Krein spaces the notions of spectral points of positive and negative type are basic in the spectral and perturbation theory of these operators. The aim of this paper is to give different characterizations of these sign types of spectral points. Moreover a local variant of definitizability is characterized in various ways.