Remarks on numerical ranges of operators in spaces with an indefinite metric
نویسندگان
چکیده
منابع مشابه
Ela Numerical Ranges of Quadratic Operators in Spaces with an Indefinite Metric
The numerical range of a quadratic operator acting on an indefinite inner product space is shown to have a hyperbolical shape. This result is extended to different kinds of indefinite numerical ranges, namely, indefinite higher rank numerical ranges and indefinite Davis-Wielandt shells.
متن کاملRemarks on generalized numerical ranges of operators on indefinite inner product spaces
Numerical ranges associated to operators on an indefinite inner product space are investigated. Boundary generating curves, shapes, corners and computer generation of these sets are studied. Some final remarks present an interesting relation between these sets and numerical ranges of operators arising in quantum mechanics.
متن کاملNumerical ranges of quadratic operators in spaces with an indefinte metric
The numerical range of a quadratic operator acting on an indefinite inner product space is shown to have a hyperbolical shape. This result is extended to different kinds of indefinite numerical ranges, namely, indefinite higher rank numerical ranges and indefinite Davis-Wielandt shells.
متن کاملOn the Geometry of Numerical Ranges in Spaces with an Indefinite Inner Product
Geometric properties of the numerical ranges of operators on an indefinite inner product space are investigated. In particular, classes of matrices are presented such that the boundary generating curves of the J-numerical range are hyperbolical. The curvature of the J-numerical range at a boundary point is studied, generalizing results of Fiedler on the classical numerical range.
متن کاملRemarks on the Paper ``Coupled Fixed Point Theorems for Single-Valued Operators in b-Metric Spaces''
In this paper, we improve some recent coupled fixed point resultsfor single-valued operators in the framework of ordered $b$-metricspaces established by Bota et al. [M-F. Bota, A. Petrusel, G.Petrusel and B. Samet, Coupled fixed point theorems forsingle-valued operators in b-metric spaces, Fixed Point TheoryAppl. (2015) 2015:231]. Also, we prove that Perov-type fix...
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ژورنال
عنوان ژورنال: Proceedings of the American Mathematical Society
سال: 1998
ISSN: 0002-9939,1088-6826
DOI: 10.1090/s0002-9939-98-04242-7