A Schur Type Analysis of the Minimal Unitary Hubert Space Extensions of a Krein Space Isometry whose Defect Subspaces are Hubert Spaces
Author(s) -
Aad Dijksma,
Stefania Marcantognini,
H. S. V. de Snoo
Publication year - 1994
Publication title -
zeitschrift für analysis und ihre anwendungen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.567
H-Index - 35
eISSN - 1661-4534
pISSN - 0232-2064
DOI - 10.4171/zaa/513
Subject(s) - linear subspace , isometry (riemannian geometry) , unitary state , space (punctuation) , pure mathematics , type (biology) , mathematics , algebra over a field , computer science , ecology , political science , law , biology , operating system
We consider a Kreln space isometry whose defect subspaces are Hilbert spaces and we show that its minimal unitary Hilbert space extensions are related to one-step isometric Hilbert space extensions and Schur parameters. These unitary extensions give rise to moments and scattering matrices defined on a scale subspace. By means of these notions we solve the labeling problem for the contractive intertwining liftings in the commutant lifting theorem for Kreln space contractions.
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