Takuya HOSOKAWAAssociate Professor
■Researcher basic information
Organization
Research Keyword
Educational Background
- 01 Apr. 2000 - 31 Mar. 2003, Niigata University, Graduate School of Science and Technology, 情報理工学専攻
- Apr. 2000 - Mar. 2003, Niigata University, Graduate School of Science and Technology, 情報理工学専攻
- 01 Apr. 1998 - 31 Mar. 2000, Kyoto University, Graduate School, Division of Natural Science, 数学・数理解析専攻
- Apr. 1998 - Mar. 2000, Kyoto University, Graduate School, Division of Natural Science, 数学・数理解析専攻
- Apr. 1994 - Mar. 1998, Kyoto University, Faculty of Science, 理学科
Career
Member History
■Research activity information
Paper
- Integral-type operators between the weighted Lipschitz spaces on a tree
Toshikazu Abe; Takuya Hosokawa
Nihonkai Mathematical Journal, Jul. 2021, [Reviewed] - Weighted composition operators acting from the Lipschitz space to the space of bounded functions on a tree
We study the weighted composition operators between the Lipschitz space and the space of bounded functions on the set of vertices of an infinite tree. ,We characterize the boundedness, the compactness, and the boundedness from below of weighted composition operators. We also determine the isometric weighted composition operators.
Acta Scientiarum Mathematicarum (Szeged), Apr. 2020, [Reviewed] - Weighted composition operators between Hilbert spaces of analytic functions in the operator norm and Hilbert-Schmidt norm topologies
Takuya Hosokawa; Kei Ji Izuchi; Shuichi Ohno, We here investigate the topological structure of the space of weighted composition operators boundedly acting between two Hilbert spaces of analytic functions on the open unit disk, satisfying some natural hypotheses. We will consider the operator norm topology and the Hilbert-Schmidt norm topology respectively. These results will be involved-in the investigation for the explicit cases of the classical Hardy-Hilbert space, the weighted Bergman spaces and the Dirichlet space. Furthermore we will estimate the Hilbert-Schmidt norms of difference of two composition operators acting from the Dirichlet space to the Hardy and the weighted Bergman spaces. (c) 2014 Elsevier Inc. All rights reserved., ACADEMIC PRESS INC ELSEVIER SCIENCE
JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS, Jan. 2015, [Reviewed] - Some remarks on operator equation $C_\varphi = C_\psi X$
Takuya Hosokawa; Michio Seto
Nihonkai Mathematical Journal, 2014, [Reviewed] - DIFFERENCES OF WEIGHTED COMPOSITION OPERATORS FROM H-infinity TO BLOCH SPACE
Takuya Hosokawa; Shuichi Ohno, We consider the boundedness and compactness of the differences of two weighted composition operators acting from the Banach space of bounded analytic functions on the open unit disk to the Bloch space. In the sequel, we will present some explicit examples to bring our reseach into forcus., MATHEMATICAL SOC REP CHINA
TAIWANESE JOURNAL OF MATHEMATICS, Dec. 2012, [Reviewed] - Hilbert-Schmidt differences of composition operators on the Bergman space
Boo Rim Choe; Takuya Hosokawa; Hyungwoon Koo, In the setting of the weighted Bergman space over the unit disk, we characterize Hilbert-Schmidt differences of two composition operators in terms of integrability condition involving pseudohyperbolic distance between the inducing functions. We also show that a linear combination of two composition operators can be Hilbert-Schmidt, except for trivial cases, only when it is essentially a difference. We apply our results to study the topological structure of the space of all composition operators under the Hilbert-Schmidt norm topology. We first characterize components and then provide some sufficient conditions for isolation or for non-isolation., SPRINGER
MATHEMATISCHE ZEITSCHRIFT, Dec. 2011, [Reviewed] - DIFFERENCES OF WEIGHTED COMPOSITION OPERATORS ACTING FROM BLOCH SPACE TO H-infinity
Takuya Hosokawa; Shuichi Ohno, We study the boundedness and compactness of the differences of two weighted composition operators acting from the Bloch space B to the space H-infinity of bounded analytic functions on the open unit disk. Such a study has a relationship to the topological structure problem of composition operators on H-infinity. Using this relation, we will estimate the operator norms and the essential norms of the differences of two composition operators acting from B to H-infinity., AMER MATHEMATICAL SOC
TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY, Oct. 2011, [Reviewed] - Linear Combinations of Composition Operators on the Bloch Spaces
Takuya Hosokawa; Pekka J. Nieminen; Shuichi Ohno, We characterize the compactness of linear combinations of analytic composition operators on the Bloch space. We also study their boundedness and compactness on the little Bloch space., CANADIAN MATHEMATICAL SOC
CANADIAN JOURNAL OF MATHEMATICS-JOURNAL CANADIEN DE MATHEMATIQUES, Aug. 2011, [Reviewed] - Differences of weighted composition operators acting from Bloch space to $H^\infty$
Takuya Hosokawa; Sh\^{u}ichi Ohno
Transactions of the American Mathematical Society, 2011, [Reviewed] - Eigenvalues of Weighted Composition Operators on the Bloch Space
Takuya Hosokawa; Quang Dieu Nguyen, This note discusses eigenvalues of weighted composition operators uC (phi) on the Bloch space. The main result provides a class of uC (phi) for which computation of eigenvalues is possible. We also construct an example of a non-compact operator C (phi) whose eigenvalues can be determined precisely., BIRKHAUSER VERLAG AG
INTEGRAL EQUATIONS AND OPERATOR THEORY, Apr. 2010, [Reviewed] - Differences of Weighted Composition Operators on the Bloch Spaces
Takuya Hosokawa, We study the boundedness and the compactness of the differences of weighted composition operators on the Bloch spaces. The results generalize the corresponding results on the single weighted composition operators and on the differences of composition operators., BIRKHAUSER VERLAG AG
COMPLEX ANALYSIS AND OPERATOR THEORY, Dec. 2009, [Reviewed] - THE ESSENTIAL NORM OF A WEIGHTED COMPOSITION OPERATOR FROM THE BLOCH SPACE TO H-infinity
Takuya Hosokawa, We express the operator norm of a weighted composition operator which acts from the Bloch space B to H-infinity as the supremum of a quantity involving the weight function, the inducing self-map, and the hyperbolic distance. We also express the essential norm of a weighted composition operator from B to H-infinity as the asymptotic upper bound of the same quantity. Moreover we study the estimate of the essential norm of a weighted composition operator from H-infinity to itself., CAMBRIDGE UNIV PRESS
BULLETIN OF THE AUSTRALIAN MATHEMATICAL SOCIETY, Jun. 2009, [Reviewed] - Weighted composition operators on the logarithmic Bloch spaces,with iterated weights
Takuya Hosokawa; Nguyen Quang Dieu, Niigata University
Nihonkai Mathematical Journal, 2009, [Reviewed] - Extreme points of the closed convex hull of composition operators
Takuya Hosokawa, We study the extreme points of the closed convex hull of the set of all composition operators on the space of bounded analytic functions and the disk algebra. (C) 2008 Elsevier Inc. All rights reserved., ACADEMIC PRESS INC ELSEVIER SCIENCE
JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS, Nov. 2008 - Differences of composition operators on the Bloch spaces
Takuya Hosokawa; Sh\^{u}ichi Ohno
Journal of Operator Theory, Apr. 2007, [Reviewed] - Topological structures of the sets of composition operators on the Bloch spaces
T Hosokawa; S Ohno, We study properties of the topological sets of composition operators on Bloch and little Bloch spaces in the operator topology. (c) 2005 Elsevier Inc. All rights reserved., ACADEMIC PRESS INC ELSEVIER SCIENCE
JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS, Feb. 2006, [Reviewed] - Minimum moduli of weighted composition operators on algebras of analytic functions
Takuya Hosokawa, We study the minimum moduli of weighted composition operators on the disk algebra and the space of bounded analytic functions. © 2006, Department of Mathematics, Tokyo Institute of Technology. All rights reserved.
Kodai Mathematical Journal, 2006, [Reviewed] - Topological structure of the space of weighted composition operators on H-infinity
T Hosokawa; K Izuchi; S Ohno, We study properties of the topological space of weighted composition operators on the space of bounded analytic functions on the open unit disk in the uniform operator topology. Moreover, we characterize the compactness of differences of two weighted composition operators., BIRKHAUSER VERLAG AG
INTEGRAL EQUATIONS AND OPERATOR THEORY, Dec. 2005, [Reviewed] - Essential norms of differences of composition operators on H-infinity
T Hosokawa; K Izuchi, We study essential norms of differences of composition operators on the Banach algebra H-infinity of bounded analytic functions on the unit disk., MATH SOC JAPAN
JOURNAL OF THE MATHEMATICAL SOCIETY OF JAPAN, Jul. 2005, [Reviewed] - Chaotic behavior of composition operators on the Hardy space
Takuya Hosokawa
Acta Scientiarum Mathematicarum(Szeged), 2003, [Reviewed] - Isolated points and essential components of composition operators on H infinity
T Hosokawa; K Izuchi; D Zheng, We consider the topological space of all composition operators on the Banach algebra of bounded analytic functions on the unit disk. We obtain a function theoretic characterization of isolated points and show that each isolated composition operator is essentially isolated., AMER MATHEMATICAL SOC
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY, 2002, [Reviewed]
Lectures, oral presentations, etc.
- Some operators on power growth spaces on a tree
2021年度関数環研究集会, 17 Dec. 2021 - tree上の関数空間とその上の荷重合成作用素
細川卓也
2020年度関数環研究集会, 27 Nov. 2020 - Weighted composition operators between Bergman spaces
細川卓也
Real, Complex and Functional Analysis Seminar 2019, 09 Nov. 2019 - Composition operators induced by products of analytic self-maps
細川卓也
Spring Central and Western Joint Sectional Meeting of American Mathematical Society, 23 Mar. 2019, [Invited] - Integral operators acting from Bergman spaces to BMOA-type spaces
細川卓也
2018年度関数環研究集会, 30 Nov. 2018 - On some operators on function spaces on trees
細川卓也
Real, Complex and Functional Analysis Seminar 2018, 18 Nov. 2018 - 写像の葉数と作用素の挙動について
細川卓也
防大関数解析セミナー, 22 Jun. 2018 - Composition operators with product symbols
細川卓也
Real, Complex and Functional Analysis Seminar 2017, 16 Dec. 2017 - Composition operators with product symbols
細川卓也
第39回東北複素解析セミナー, 29 Nov. 2017 - 解析関数空間上の合成作用素の成す集合の位相構造について
細川卓也
関東作用素論セミナー, 20 May 2017 - 単位円板上の正則自己写像の積と合成作用素の性質について
細川卓也
つくばセミナー, 08 Mar. 2016 - Composition operators with product symbols
細川卓也
2015年度 関数環研究集会, 19 Dec. 2015 - Weighted composition operators between Hilbert spaces of analytic functions in Hilbert-Schmidt norm topologies
細川卓也
日本数学会２０１５年度秋季総合分科会, 15 Sep. 2015 - Linear combinations of composition operators on H^∞ and the Bloch space
２０１３年作用素論・作用素環論研究集会, 24 Nov. 2013, [Invited] - Differences of weighted composition operators from H∞ to the Bloch space
2013日本数学会秋季総合分科会, 25 Sep. 2013 - Some notes on composition operators on the Bloch space
第21回宮代セミナー, 31 Oct. 2012 - Differences of weighted composition operators from the Bloch space to H∞
2012 日本数学会 秋季総合分科会, 20 Sep. 2012 - Differences of weighted composition operators between H∞ and the Bloch spaces
Functional Analysis Seminar, 28 Aug. 2012 - Eigenvalues of weighted composition operators on the Bloch space
日本数学会2012年会, 27 Mar. 2012 - Linear combinations of composition operators on the Bloch space
日本数学会2012年会, 27 Mar. 2012 - Integral type operators from H∞
2011年度関数環研究集会, 02 Dec. 2011 - Composition operators from H∞ to the little Bloch space
第20回宮代セミナー, 18 Aug. 2011 - Differences of composition operators between H∞ and the Bloch space
2010年度関数環研究集会, 30 Nov. 2010 - Extreme points of the closed convex hull of composition operators on H∞
2010 日本数学会 秋季総合分科会, 25 Sep. 2010 - Norms and essential norms of weighted composition operators between the Bloch space and H∞
2010 日本数学会 秋季総合分科会, 25 Sep. 2010 - Linear combinations of composition operators on H∞ and the Bloch spaces
2009年度関数環研究集会, 27 Nov. 2009 - Differences of weighted composition operators between H∞ and the Bloch space
第52回函数論シンポジウム, 21 Nov. 2009 - Differences of weighted composition operators on the Bloch space
2009 日本数学会 秋季総合分科会, 26 Sep. 2009
Research Themes
- Functional analysis approach to time evolution of graphs and its application
Grant-in-Aid for Scientific Research (C)
防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群)
01 Apr. 2020 - 31 Mar. 2024 - Hardy空間とBergman空間の間の荷重合成作用素の研究
基盤研究(C)
Apr. 2021 - Mar. 2024 - Study of graph homomorphisms from functional analysis
Grant-in-Aid for Scientific Research (C)
防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群)
01 Apr. 2015 - 31 Mar. 2019 - 解析関数の乗法演算と合成演算の代数構造と位相構造の研究
基盤研究(C)
Apr. 2016 - Mar. 2019 - Researches on the structures of analytic function spaces and linear operators on them
Grant-in-Aid for Scientific Research (C)
Nippon Institute of Technology
01 Apr. 2015 - 31 Mar. 2018 - 解析関数への乗法演算と合成演算の位相構造の研究
若手研究(B)
Apr. 2013 - Mar. 2016 - Researches on the structures of the spaces of analytic and harmonic functions and operators on them
Grant-in-Aid for Scientific Research (C)
Nippon Institute of Technology
01 Apr. 2012 - 31 Mar. 2015 - Study on the well-posedness of hyperbolic equation with memory
Grant-in-Aid for Scientific Research (C)
Ibaraki University
01 Apr. 2012 - 31 Mar. 2015 - Functional analytic research of hyperbolic equations with memory
Grant-in-Aid for Scientific Research (C)
Ibaraki University
2008 - 2011
