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Complex symmetry of Toeplitz operators and composition operators

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Denote by $H_{\gamma}(\mathbb{D})$ the Hilbert space of holomorphic functions over the open unit disk $\mathbb{D}$ with the reproducing kernel $K_{\omega}^{(\gamma)}(z)=\frac{1}{(1-\overline{\omega}z)^{\gamma}}$, $\gamma>0$. Let $J_{\alpha}: J_{\alpha}f(z)=\overline{f(\overline{\alpha z})}$ for $z\in \mathbb{D}$ and $\alpha \in \partial \mathbb{D}$, and let $W_{u,v}$ be the weighted composition operator. In this paper, we prove that if $b\in \mathbb{R}$ and $b\neq \frac{k\pi}{2}$, for any integer $k$, then $(\cos b+i\sin bW_{u,v})J_{\alpha}$ is a conjugation if and only if $v(z)=\frac{c-z}{1-\overline{c}z}$, $u(z)=\pm k_{c}^{(\gamma)}(z)$, $c\in\mathbb{D}$ and $\overline{c}=c\alpha$, where $k_c^{(\gamma)}(z)$ is the normalized reproducing kernel, or $(\cos b+i\sin bW_{u,v})J_{\alpha}=\lambda J_{\alpha}$ for some $\lambda\in \mathbb{C}$ with $|\lambda|=1$. We then derive a necessary and sufficient condition for a Toeplitz operator to be complex symmetric with respect to the conjugation $(\cos b+i\sin bW_{u,v})J_{\alpha}$ on $H_{\gamma}(\mathbb{D})$ with $\gamma \geq 1$. Similarly, we also conduct a similar study for composition operators on $H_{\gamma}(\mathbb{D})$ with $\gamma >0$.

Abstract

Denote by $H_{\gamma}(\mathbb{D})$ the Hilbert space of holomorphic functions over the open unit disk $\mathbb{D}$ with the reproducing kernel $K_{\omega}^{(\gamma)}(z)=\frac{1}{(1-\overline{\omega}z)^{\gamma}}$, $\gamma>0$. Let $J_{\alpha}: J_{\alpha}f(z)=\overline{f(\overline{\alpha z})}$ for $z\in \mathbb{D}$ and $\alpha \in \partial \mathbb{D}$, and let $W_{u,v}$ be the weighted composition operator. In this paper, we prove that if $b\in \mathbb{R}$ and $b\neq \frac{k\pi}{2}$, for any integer $k$, then $(\cos b+i\sin bW_{u,v})J_{\alpha}$ is a conjugation if and only if $v(z)=\frac{c-z}{1-\overline{c}z}$, $u(z)=\pm k_{c}^{(\gamma)}(z)$, $c\in\mathbb{D}$ and $\overline{c}=c\alpha$, where $k_c^{(\gamma)}(z)$ is the normalized reproducing kernel, or $(\cos b+i\sin bW_{u,v})J_{\alpha}=\lambda J_{\alpha}$ for some $\lambda\in \mathbb{C}$ with $|\lambda|=1$. We then derive a necessary and sufficient condition for a Toeplitz operator to be complex symmetric with respect to the conjugation $(\cos b+i\sin bW_{u,v})J_{\alpha}$ on $H_{\gamma}(\mathbb{D})$ with $\gamma \geq 1$. Similarly, we also conduct a similar study for composition operators on $H_{\gamma}(\mathbb{D})$ with $\gamma >0$.

참고문헌 (14)

  1. Q. Bu, "Complex symmetric Toeplitz operators", Integral Equations Operator Theory, 93(2), pp.15~ (2021)[DOI]
  2. Y. Chen, "Complex symmetry of Toeplitz operators", Banach J. Math. Anal, 16(1), pp.23~ (2022)[DOI]
  3. S. R. Garcia, "Which weighted composition operators are complex symmetric?, Concrete operators, spectral theory, operators in harmonic analysis and approximation", pp.2014, Birkhauser
  4. S. R. Garcia, "Complex symmetric operators and applications", Trans. Amer. Math. Soc, 358(3), pp.1285~1315 (2006)[DOI]
  5. S. R. Garcia, "Complex symmetric operators and applications. II", Trans. Amer. Math. Soc, 359(8), pp.3913~3931 (2007)[DOI]
  6. K. Guo, "A canonical decomposition of complex symmetric operators", J. Operator Theory, 72(2), pp.529~547 (2014)[DOI]
  7. E. Ko, "On complex symmetric Toeplitz operators", J. Math. Anal. Appl, 434(1), pp.20~34 (2016)[DOI]
  8. E. Ko, "Complex symmetric Toeplitz operators on the weighted Bergman space", Complex Var. Elliptic Equ, 67(6), pp.1393~1408 (2022)[DOI]
  9. T. Le, "Self-adjoint, unitary, and normal weighted composition operators in several variables", J. Math. Anal. Appl, 395(2), pp.596~607 (2012)[DOI]
  10. R. Li, "A class of complex symmetric Toeplitz operators on Hardy and Bergman spaces", J. Math. Anal. Appl, 489(2), pp.124173~ (2020)[DOI]
  11. R. Lim, "Complex symmetric weighted composition operators on Hγ(D)", J. Math. Anal. Appl, 464(1), pp.101~118 (2018)[DOI]
  12. C. -O. Lo, "Complex symmetric generalized weighted composition operators on Hilbert spaces of analytic functions", J. Math. Anal. Appl, 523(2), pp.127141~ (2023)[DOI]
  13. C. -O. Lo, "Complex symmetric Toeplitz operators on Hilbert spaces of analytic functions", Mediterr. J. Math, 20(3), pp.175~ (2023)[DOI]
  14. K. Zhu, "Operator Theory in Function Spaces" (2007), Amer. Math. Soc

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