Some invariant subspaces for A-contractions and applications

Título inglés	Some invariant subspaces for A-contractions and applications
Título español	Algunos subespacios invariantes para A-contracciones y aplicaciones.
Autor/es	Suciu, Laurian
Organización	Inst. "Camille Jordan" Univ. Claude Bernard Lyon 1, Villeurbanne, Francia
Revista	0213-8743
Publicación	2006, 21 (3): 221-247, 12 Ref.
Tipo de documento	articulo
Idioma	Inglés
Resumen inglés	Some invariant subspaces for the operators A and T acting on a Hilbert space H and satisfying T*AT ≤ A and A ≥ 0, are presented. Especially, the largest invariant subspace for A and T on which the equality T* AT = A occurs, is studied in connections to others invariant or reducing subspaces for A, or T. Such subspaces are related to the asymptotic form of the subspace quoted above, this form being obtained using the operator limit of the sequence {T*nATn; n ≥ 1}. More complete results are given in the case when AT = A1/2TA1/2. Also, several applications for quasinormal operators are derived, involving their unitary, isometric and quasi-isometric parts, as well as their asymptotic behaviour.
Clasificación UNESCO	120200
Palabras clave español	Teoría de operadores ; Operadores lineales ; Subespacio invariante ; Contracción
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