Results 261 to 270 of about 1,270,350 (303)

Bounded characteristic functions and models for noncontractive sequences of operators

Integral Equations and Operator Theory, 2003
In the paper under review, the Sz.-Nagy-Foiaş functional model for completely non-unitary contractions is extended to completely non-coisometric sequences of bounded operators on a Hilbert space \(H\). It was shown in [\textit{B. Sz.-Nagy} and \textit{C. Foiaş}, C. R. Acad.
Gheondea, Aurelian, Popescu, Gelu
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Reference functional and characteristic space for Lagrange and Bernstein operators

Approximation Theory and its Applications, 1995
The authors apply the concept of reference functionals and characteristic spaces, introduced in [\textit{C. Brezinski} and the reviewer, J. Comput. Appl. Math. 34, No. 3, 361-383 (1991; Zbl 0732.65004)], to the case of multivariate polynomials over simplices. In particular, they consider interpolating polynomials, computed by the de Casteljau operator.
DE MARCHI, STEFANO, M. MORANDI CECCHI
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Characteristic Functions of Maximal Sectorial Operators

2001
The analytic properties of the characteristic functions of maximal sectorial operators are studied and functional models are constructed.
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Regular factorizations of a characteristic function and singular operator-functions

Functional Analysis and Its Applications, 1991
Regular factorizations of contractive characteristic functions are studied in the book of \textit{B. Sz.-Nagy} and \textit{C. Foiaş} [Harmonic analysis of operators on Hilbert space. Budapest: Akadémiai Kiadó (1970; Zbl 0201.45003), Chapter 7]. It is shown that they correspond to invariant subspaces for the associated operator.
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Sectorial extensions of a positive operator and the characteristic function

Ukrainian Mathematical Journal, 1989
See the review in Zbl 0669.47022.
Derkach, V. A., Malamud, M. M., Tsekanovskij, Eh. R.   +2 more
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Expansions in Characteristic Vectors of Nonunitary Operators and the Characteristic Function

1970
In this paper we shall establish necessary and sufficient conditions for a system of characteristic vectors of a nonunitary operator in Hilbert space to form an unconditional basis (i.e., a basis similar to an orthonormal basis). These conditions will be formulated in terms of the characteristic function of the operator and its functional model, as ...
N. K. Nikol’skii, B. S. Pavlov
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Automorphic-invariant operator colligations and the factorization of their characteristic operator functions

Functional Analysis and Its Applications, 1988
In these notes is given an exposition focused on the automorphically invariant operator nodes and factorization of their characteristic operator-functions.
Filimonov, A. P., Tsekanovskij, Eh. R.
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On characteristic functions of maximal dissipative operators

Complex Analysis and Operator Theory
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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A problem concering characteristic functions of linear operators

Mathematical Notes of the Academy of Sciences of the USSR, 1971
The construction of a bounded operator in terms of its characteristic function is investigated.
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The Krein String and Characteristic Functions of Maximal Dissipative Operators

Journal of Mathematical Sciences, 2004
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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