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Dive into the research topics where Ruhan Zhao is active.

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Featured researches published by Ruhan Zhao.


Integral Equations and Operator Theory | 2001

Topological structure of the space of composition operators onH

Barbara Maccler; Shûichi Ohno; Ruhan Zhao

Components and isolated points of the topological space of composition operators onH∞ in the uniform operator topology are characterized. Compact differences of two composition operators are also characterized. With the aid of these results, we show that a component inC(H∞) is not in general the set of all composition operators that differ from the given one by a compact operator.


Journal of The London Mathematical Society-second Series | 2004

Weighted Composition Operators on the Bergman Space

Zeljko Cucković; Ruhan Zhao

Bounded, compact and Schatten class weighted composition operators on the Bergman space are characterized by the use of generalized Berezin transforms. An estimate of the essential norms of weighted composition operators on the Bergman space is given. Most of the results remain true for Hardy spaces and weighted Bergman spaces.


Bulletin of The Australian Mathematical Society | 2001

Weighted composition operators on the Bloch space

Shûichi Ohno; Ruhan Zhao

f = uf o ip.It is easy to see that an operator defined in this manner is linear. We can regard thisoperator as a generalisation of a multiplication operator and a composition operator.In this note we study the boundedness and the compactness of weighted compositionoperators on the Bloch space and the little Bloch space. Recall that a function /analytic in D is said to belong to the Bloch space B ifsup(l-|z|


Proceedings of the American Mathematical Society | 2003

Generalized Schwarz-Pick estimates

Barbara D. MacCluer; Karel Stroethoff; Ruhan Zhao

We obtain higher derivative generalizations of the Schwarz-Pick inequality for analytic self-maps of the unit disk as a consequence of recent characterizations of boundedness and compactness of weighted composition operators between Bloch-type spaces.


Complex Variables | 2003

Schwarz–Pick Type Estimates

Barbara D. MacCluer; Karel Stroethoff; Ruhan Zhao

We obtain estimates on higher-order derivatives that generalize the classical Schwarz–Pick inequality for analytic self-maps of the unit disk. We discuss further extensions involving certain weight functions, converse results, and versions of all of these results in the setting of the unit ball in .


Proceedings of the American Mathematical Society | 2006

Toeplitz operators on Bloch-type spaces

Zhijian Wu; Ruhan Zhao; Nina Zorboska

We characterize complex measures μ on the unit disk for which the Toeplitz operator T α μ , a > 0, is bounded or compact on the Bloch type spaces B α .


Mathematical Proceedings of the Cambridge Philosophical Society | 2007

Essential norm estimates of weighted composition operators between Bergman spaces on strongly pseudoconvex domains

Zeljko Cucković; Ruhan Zhao

We give estimates of the essential norms of weighted composition operators acting between Bergman spaces on strongly pseudoconvex domains. We also characterize boundedness and compactness of these operators.


Analysis | 1995

ON SUBSPACES AND SUBSETS OF BMOA AND UBC

Rauno Aulaskari; Jie Xiao; Ruhan Zhao


Rocky Mountain Journal of Mathematics | 2003

Weighted Composition Operators between Bloch-Type Spaces

Shûichi Ohno; Karel Stroethoff; Ruhan Zhao


Rocky Mountain Journal of Mathematics | 2003

Essential Norms of Weighted Composition Operators between Bloch-Type Spaces

Barbara D. MacCluer; Ruhan Zhao

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Shûichi Ohno

Nippon Institute of Technology

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Jordi Pau

University of Barcelona

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Rauno Aulaskari

University of Eastern Finland

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Jie Xiao

Michigan State University

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Kehe Zhu

State University of New York System

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