On the geometry of normal projections in Krein spaces

Let H be a Krein space with fundamental symmetry J. Along this paper, the geometric structure of the set of J-normal projections Q is studied. The group of J-unitary operators UJ naturally acts on Q. Each orbit of this action turns out to be an analytic homogeneous space of UJ, and a connected compo...

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Autores principales: Chiumiento, Eduardo Hernán, Maestripieri, Alejandra Laura, Martínez Pería, Francisco Dardo
Formato: Articulo Preprint
Lenguaje:Inglés
Publicado: 2015
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Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/101041
https://ri.conicet.gov.ar/11336/17759
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Sumario:Let H be a Krein space with fundamental symmetry J. Along this paper, the geometric structure of the set of J-normal projections Q is studied. The group of J-unitary operators UJ naturally acts on Q. Each orbit of this action turns out to be an analytic homogeneous space of UJ, and a connected component of Q. The relationship between Q and the set E of J-selfadjoint projections is analized: both sets are analytic submanifolds of L(H) and there is a natural real analytic submersion from Q onto E, namely Q↦QQ#. The range of a J-normal projection is always a pseudo-regular subspace. Then, for a fixed pseudo-regular subspace S, it is proved that the set of J-normal projections onto S is a covering space of the subset of J-normal projections onto S with fixed regular part.