Catálogo de publicaciones - libros
Operator Theory in Inner Product Spaces
Karl-Heinz Förster ; Peter Jonas ; Heinz Langer ; Carsten Trunk (eds.)
Resumen/Descripción – provisto por la editorial
No disponible.
Palabras clave – provistas por la editorial
Operator Theory; Functions of a Complex Variable; Functional Analysis
Disponibilidad
Institución detectada | Año de publicación | Navegá | Descargá | Solicitá |
---|---|---|---|---|
No detectada | 2007 | SpringerLink |
Información
Tipo de recurso:
libros
ISBN impreso
978-3-7643-8269-8
ISBN electrónico
978-3-7643-8270-4
Editor responsable
Springer Nature
País de edición
Reino Unido
Fecha de publicación
2007
Información sobre derechos de publicación
© Birkhäuser Verlag AG 2007
Cobertura temática
Tabla de contenidos
Normal Matrices in Degenerate Indefinite Inner Product Spaces
Christian Mehl; Carsten Trunk
Complex matrices that are structured with respect to a possibly degenerate indefinite inner product are studied. Based on the theory of linear relations, the notion of an adjoint is introduced: the adjoint of a matrix is defined as a linear relation which is a matrix if and only if the inner product is nondegenerate. This notion is then used to give alternative definitions of selfadjoint and unitary matrices in degenerate inner product spaces and it is shown that those coincide with the definitions that have been used in the literature before. Finally, a new definition for normal matrices is given which allows the generalization of an extension result for positive invariant subspaces from the case of nondegenerate inner products to the case of degenerate inner products.
Palabras clave: Degenerate inner product space; adjoint; linear relations; -self-adjoint; -unitary; -normal.
Pp. 193-209
Symmetric Hermite-Biehler Polynomials with Defect
Vyacheslav Pivovarchik
The polynomial ω = P ( λ ) + iQ ( λ ) with real P ( λ ) and Q ( λ ) which belongs to Hermite-Biehler class (all its zeros lie in the open upper half-plane) and is symmetric $$ (\omega ( - \bar \lambda ) = \overline {\omega (\lambda )} ) $$ is modified as follows $$ (\omega _c (\lambda ) = \tilde P(\lambda ^2 + c) + i\lambda \tilde \hat Q(\lambda ^2 + c), c > 0. $$ Here $$ \tilde P(\lambda ^2 ) = P(\lambda ),\tilde \hat Q(\lambda ^2 ) = \lambda ^{ - 1} Q(\lambda ) $$ and $$ P(\lambda ) = \frac{{\omega (\lambda ) + \omega ( - \lambda )}} {2},Q(\lambda ) = \frac{{\omega (\lambda ) - \omega ( - \lambda )}} {{2i}} $$ The conditions are obtained necessary and sufficient for a set of complex numbers to be the zeros of a polynomial of the form ω _c( λ ).
Palabras clave: Hermite-Biehler polynomial; Hurwitz polynomials; zeros in the lower half-plane.
Pp. 211-224
A Note on Indefinite Douglas’ Lemma
Leiba Rodman
The Douglas lemma on majorization and factorization of Hilbert space operators is extended to the setting of Krein space operators.
Palabras clave: Majorization; factorization; Hilbert space operators; Krein spaces.
Pp. 225-229
Some Basic Properties of Polynomials in a Linear Relation in Linear Spaces
Adrian Sandovici
The behavior of the domain, the range, the kernel and the multivalued part of a polynomial in a linear relation is analyzed, respectively.
Palabras clave: Polynomial; linear space; linear relation; domain; range; kernel; multivalued part.
Pp. 231-240