A Schur type analysis of the minimal unitary Hilbert space extensions of a Kreĭn space isometry whose defect subspaces are Hilbert spaces
Summary: We consider a Kreĭn 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 Kreĭn space contractions.
minimal unitary Hilbert space extensions
one- step isometric Hilbert space extensions
commutant lifting theorem for Kreĭn space contractions
scientific article; zbMATH DE number 605108