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  1. No Access

    Article

    Difference of Weighted Composition Operators Over the Ball

    Recently, Choe et al. obtained characterizations for bounded/compact differences of weighted composition operators acting from a standard weighted Bergman space into another over the unit disk. In this paper w...

    Boo Rim Choe, Koeun Choi, Hyungwoon Koo… in Complex Analysis and Operator Theory (2024)

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    Article

    Sums of Polyanalytic Dual Toeplitz Products

    On the setting of the orthogonal complement of the polyanalytic Bergman space of the unit disk, we give characterizations of when a sum of products of several dual Toeplitz operators is compact or zero. Our re...

    Hong Rae Cho, Hyungwoon Koo, Young Joo Lee in Complex Analysis and Operator Theory (2023)

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    Article

    Local Hopf Lemma for Certain Degenerate Elliptic Operators on the Half-Space

    We prove that the local Hopf lemma of Baouendi–Rothschild for harmonic functions continues to hold for the degenerate elliptic operator, $$\ma...

    Hyungwoon Koo, Song-Ying Li in Complex Analysis and Operator Theory (2023)

  4. No Access

    Article

    Difference of Weighted Composition Operators II

    In the setting of the unit disk we have recently obtained characterizations in terms of Carleson measures for bounded/compact differences of weighted composition operators acting from a standard weighted Bergm...

    Boo Rim Choe, Koeun Choi, Hyungwoon Koo… in Integral Equations and Operator Theory (2021)

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    Article

    Evolution of the Steklov eigenvalue under geodesic curvature flow

    On a two-dimensional compact Riemannian manifold with boundary, we prove that the first nonzero Steklov eigenvalue is nondecreasing along the unnormalized geodesic curvature flow if the initial metric has posi...

    Pak Tung Ho, Hyunmo Koo in manuscripta mathematica (2019)

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    Article

    Linear Fractional Composition Operators Over the Half-Plane

    In the setting of the Hardy spaces or the standard weighted Bergman spaces over the unit ball in \({\mathbf {C}}^n\) ...

    Boo Rim Choe, Hyungwoon Koo, Wayne Smith in Integral Equations and Operator Theory (2018)

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    Article

    Composition Operators on Bounded Convex Domains in \({{\mathbb{C}}^n}\)

    We study composition operators on a class of bounded domains including convex domains \({\Omega \subset {{\mathbb{C}}^n}}\) ...

    Hyungwoon Koo, Song-Ying Li in Integral Equations and Operator Theory (2016)

  8. No Access

    Article

    Fock-Sobolev Spaces of Fractional Order

    For the full range of index 0 < p ...

    Hong Rae Cho, Boo Rim Choe, Hyungwoon Koo in Potential Analysis (2015)

  9. No Access

    Article

    Compact linear combinations of composition operators induced by linear fractional maps

    It has been known that the difference of two composition operators induced by linear fractional self-maps of a ball cannot be nontrivially compact on either the Hardy space or any standard weighted Bergman spa...

    Boo Rim Choe, Hyungwoon Koo, Maofa Wang, Jongho Yang in Mathematische Zeitschrift (2015)

  10. No Access

    Article

    Linear Combinations of Composition Operators on the Fock-Sobolev Spaces

    We study linear combinations of composition operators acting on the Fock-Sobolev spaces of several variables. We show that such an operator is bounded only when all the composition operators in the combination...

    Hong Rae Cho, Boo Rim Choe, Hyungwoon Koo in Potential Analysis (2014)

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    Article

    Zygmund Type Mean Lipschitz Spaces on the Unit Ball of ℂ n

    On the unit ball of ℂ n , the space of those holomorphic functions satisfying mean Lipschitz condition ...

    Ern Gun Kwon, Hong Rae Cho, Hyungwoon Koo in Potential Analysis (2014)

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    Article

    Compact Differences of Composition Operators on the Bergman Spaces Over the Ball

    The compact differences of composition operators acting on the weighted L 2-Bergman space over the unit disk is characterized by the angular derivative cancellation property and due to Moorhouse. ...

    Boo Rim Choe, Hyungwoon Koo, Inyoung Park in Potential Analysis (2014)

  13. No Access

    Article

    Ranks of commutators of Toeplitz operators on the harmonic Bergman space

    We study the rank of commutators of two Toeplitz operators on the harmonic Bergman space of the unit disk. We first show that the commutator of any two Toeplitz operators with general symbols can’t have an odd...

    Yong Chen, Hyungwoon Koo, Young Joo Lee in Integral Equations and Operator Theory (2013)

  14. No Access

    Article

    Hardy–Carleson Measures and Their Dual Poisson–Szegö Transforms

    Recently Choe et al. have introduced the notion of dual Berezin transforms and used it to obtain new characterizations of the Carleson measures for the weighted Bergman spaces over the unit ball in C ...

    Boo Rim Choe, Kou Hei Izuchi, Hyungwoon Koo in Potential Analysis (2013)

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    Article

    Compact Differences of Composition Operators over Polydisks

    Moorhouse characterized compact differences of composition operators acting on a weighted Bergman space over the unit disk of the complex plane. She also found a sufficient condition for a single composition o...

    Boo Rim Choe, Hyungwoon Koo, Inyoung Park in Integral Equations and Operator Theory (2012)

  16. No Access

    Article

    Hilbert–Schmidt differences of composition operators on the Bergman space

    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...

    Boo Rim Choe, Takuya Hosokawa, Hyungwoon Koo in Mathematische Zeitschrift (2011)

  17. No Access

    Article

    Finite Sums of Toeplitz Products on the Polydisk

    On the Bergman space of the unit polydisk, we study a class of operators which contains sums of finitely many Toeplitz products with pluriharmonic symbols. We give characterizations of when an operator in that...

    Boo Rim Choe, Hyungwoon Koo, Young Joo Lee in Potential Analysis (2009)

  18. No Access

    Article

    Carleson Measures via BMO

    We obtain new characterizations of Carleson measures via uniform boundedness of BMO norms of certain mass functions associated with the given measure in a natural way.

    Boo Rim Choe, Hyungwoon Koo, Michael Stessin in Integral Equations and Operator Theory (2009)

  19. No Access

    Article

    Carleson measures for the area Nevanlinna spaces and applications

    Let 1 ≤ p < ∞ and let μ be a finite positive Borel measure on the unit disk D. The area Nevanlinna-Lebesgue space N p (μ) consists of all measurable func...

    Boo Rim Choe, Hyungwoon Koo, Wayne Smith in Journal d'Analyse Mathématique (2008)

  20. No Access

    Article

    Positive Schatten(-Herz) Class Toeplitz Operators on the Half-space

    On the harmonic Bergman space of the half-space, we give characterizations for an arbitrary positive Toeplitz operator to be a Schatten (or Schatten-Herz) class operator in terms of averaging functions and Ber...

    Boo Rim Choe, Hyungwoon Koo, Young Joo Lee in Potential Analysis (2007)

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