Isometries of the unitary groups and Thompson isometries of the spaces of invertible positive elements in C*-algebras [PDF]
, 2014 We show that the existence of a surjective isometry (which is merely a distance preserving map) between the unitary groups of unital C*-algebras implies the existence of a Jordan *-isomorphism between the algebras.
Hatori, Osamu, Molnár, Lajos
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Algebraic reflexivity of isometry groups and automorphism groups of some operator structures [PDF]
, 2013 We establish the algebraic re exivity of three isometry groups of operator structures: The group of all surjective isometries on the unitary group, the group of all surjective isometries on the set of all positive invertible operators equipped with ...
Botelho, Fernanda +2 more
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Linear Fractional Transformations of Nevanlinna Functions Associated with a Nonnegative Operator [PDF]
, 2011 In the present paper a subclass of scalar Nevanlinna functions is studied, which coincides with the class of Weyl functions associated to a nonnegative symmetric operator of defect one in a Hilbert space.
Winkler, Henrik, +15 more
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Indefinite Hamiltonian systems whose Titchmarsh–Weyl coefficients have no finite generalized poles of non-positive type [PDF]
, 2013 The two-dimensional Hamiltonian system (*) y'(x)=zJH(x)y(x), x∈(a,b), where the Hamiltonian H takes non-negative 2x2-matrices as values, and $J:= \begin{pmatrix} 0 & -1 \\ 1 & 0 \end{pmatrix}$, has attracted a lot of interest over the past decades ...
Harald Woracek +3 more
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On difference of bivariate linear positive operators [PDF]
, 2022 In the present paper we give quantitative type theorems for the differences of different bivariate positive linear operators by using weighted modulus of continuity. Similar estimates are obtained via K-functional and for Chebyshev functionals. Moreover,
Aremu, Saheed Olaosebikan, Olgun, Ali
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Convergence of sequential and asynchronous nonlinear paracontractions [PDF]
, 1992 Elsner L, Koltracht I, Neumann M. Convergence of sequential and asynchronous nonlinear paracontractions. Numerische Mathematik. 1992;62(1):305-319.We establish the convergence of sequential and asynchronous iteration schemes for nonlinear paracontracting
Elsner, Ludwig +2 more
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The Θ-transformation of certain positive linear operators
International Journal of Mathematics and Mathematical Sciences, 1996 The intention of this paper is to describe a construction method for a new sequence of linear positive operators, which enables us to get a pointwise order of approximation regarding the polynomial summator operators which have best properties of ...
Aleandru Lupaş, Detlef H. Mache
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Unbounded functions and positive linear operators [PDF]
, 1982 The approximation of unbounded functions by positive linear operators under multiplier enlargement is investigated. It is shown that a very wide class of positive linear operators can be used to approximate functions with arbitrary growth on the real ...
Swetits, J. J. +3 more
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On the Debate Concerning the Proper Characterisation of Quantum Dynamical Evolution [PDF]
, 2012 There has been a long-standing and sometimes passionate debate between physicists over whether a dynamical framework for quantum systems should incorporate not completely positive (NCP) maps in addition to completely positive (CP) maps.
Cuffaro, Michael E. +3 more
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Completely positive linear operators for Banach spaces
International Journal of Mathematics and Mathematical Sciences, 1994 Using ideas of Pisier, the concept of complete positivity is generalized in a different direction in this paper, where the Hilbert space ℋ is replaced with a Banach space and its conjugate linear dual.
Mingze Yang
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