Opuscula Math. 44, no. 3 (2024), 373-390
Cesàro summability of Taylor series in higher order weighted Dirichlet-type spaces
Soumitra Ghara
Rajeev Gupta
Md. Ramiz Reza
Abstract.
For a positive integer \(m\) and a finite non-negative Borel measure \(\mu\) on the unit circle, we study the Hadamard multipliers of higher order weighted Dirichlet-type spaces \(\mathcal H_{\mu, m}\). We show that if \(\alpha\gt\frac{1}{2}\), then for any \(f\) in \(\mathcal H_{\mu, m}\) the sequence of generalized Cesàro sums \(\{\sigma_n^{\alpha}[f]\}\) converges to \(f\). We further show that if \(\alpha=\frac{1}{2}\) then for the Dirac delta measure supported at any point on the unit circle, the previous statement breaks down for every positive integer \(m\).
Keywords:
weighted Dirichlet-type integrals, Cesàro mean, summability, Hadamard multiplication.
Mathematics Subject Classification:
41A10, 40G05, 46E20, 41A17.
References ▼
- [1] M. Abramowitz, I.A. Stegun, Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, National Bureau of Standards Applied Mathematics Series, vol. 55, 1964.
- [2] J. Agler, M. Stankus, \(m\)-isometric transformations of Hilbert space, I, Integral Equations Operator Theory 21 (1995), no. 4, 383-429. https://doi.org/10.1007/BF01222016
- [3] J. Agler, M. Stankus, \(m\)-isometric transformations of Hilbert space, II, Integral Equations Operator Theory 23 (1995), no. 1, 1-48. https://doi.org/10.1007/BF01261201
- [4] J. Agler, M. Stankus, \(m\)-isometric transformations of Hilbert space, III, Integral Equations Operator Theory 24 (1996), no. 4, 379-421. https://doi.org/10.1007/BF01191619
- [5] J.B. Conway, The Theory of Subnormal Operators, Mathematical Surveys and Monographs, vol. 36, American Mathematical Society, 1991.
- [6] R. Curto, N. Salinas, Generalized Bergman kernels and the Cowen-Douglas theory, Amer. J. Math. 106 (1984), 447-488. https://doi.org/10.2307/2374310
- [7] D. DeTemple, W. Webb, Combinatorial Reasoning: An Introduction to the Art of Counting, John Wiley & Sons, 2014.
- [8] O. El-Fallah, K. Kellay, J. Mashreghi, T. Ransford, A Primer on the Dirichlet Space, Cambridge University Press, vol. 203, 2014. https://doi.org/10.1017/CBO9781107239425
- [9] S. Ghara, R. Gupta, Md.R. Reza, Analytic \(m\)-isometries and weighted Dirichlet-type spaces, J. Operator Theory 88 (2022), no. 2, 445-477. https://doi.org/10.48550/arXiv.2002.05470
- [10] S. Ghara, R. Gupta, Md.R. Reza, A local Douglas formula for higher order weighted Dirichlet-type integrals, J. Geom. Anal. 33 (2023), Article no. 23. https://doi.org/10.1007/s12220-023-01297-8
- [11] S. Ghara, J. Mashreghi, T. Ransford, Summability and duality, arXiv:2302.06720 (2023). https://doi.org/10.48550/arXiv.2302.06720
- [12] G.H. Hardy, Divergent Series, American Mathematical Society, 2000.
- [13] Y. Katznelson, An Introduction to Harmonic Analysis, Cambridge University Press, 2004. https://doi.org/10.1017/CBO9781139165372
- [14] S. Luo, E. Rydhe, On Dirichlet-type and \(m\)-isometric shifts in finite rank de~Branges-Rovnyak spaces, arXiv:2310.193932023 (2023). https://doi.org/10.48550/arXiv.2310.19393
- [15] J. Mashreghi, T. Ransford, Hadamard multipliers on weighted Dirichlet spaces, Integral Equations Operator Theory 91 (2019), Article no. 52. https://doi.org/10.1007/s00020-019-2551-1
- [16] J. Mashreghi, T. Ransford, Polynomial approximation in weighted Dirichlet spaces, Complex Anal. Synerg. 7 (2021), Article no. 11. https://doi.org/10.1007/s40627-021-00078-9
- [17] J. Mashreghi, P.-O. Parisè, T. Ransford, Cesàro summability of Taylor series in weighted Dirichlet spaces, Complex Anal. Oper. Theory 15 (2021), Article no. 7. https://doi.org/10.1007/s11785-020-01058-3
- [18] J. Mashreghi, P.-O. Parisè, T. Ransford, Power-series summability methods in de Branges-Rovnyak spaces, Integral Equations Operator Theory 94 (2022), no. 2, 1-17. https://doi.org/10.1007/s00020-022-02698-0
- [19] S. Richter, A representation theorem for cyclic analytic two-isometries, Trans. Amer. Math. Soc. 328 (1991), 325-349. https://doi.org/10.2307/2001885
- [20] E. Rydhe, Cyclic \(m\)-isometries and Dirichlet type spaces, J. Lond. Math. Soc. 99 (2019), no. 3, 733-756. https://doi.org/10.1112/jlms.12199
- [21] G.D. Taylor, Multipliers on \(D_{\alpha}\), Trans. Amer. Math. Soc. 123 (1966), 229-240. https://doi.org/10.1090/S0002-9947-1966-0206696-6
About the authors ▼
Soumitra Ghara
Department of Mathematics, Indian Institute of Technology Kharagpur, Midnapore - 721302, India
Rajeev Gupta
School of Mathematics and Computer Science, Indian Institute of Technology Goa, Goa - 403401, India
Md. Ramiz Reza (corresponding author)
School of Mathematics, Indian Institute of Science Education and Research Thiruvananthapuram, Kerala - 695551, India
About the article ▼
Communicated by P.A. Cojuhari.
Received: 2024-01-21.
Revised: 2024-02-04.
Accepted: 2024-02-07.
Published online: 2024-02-15.
Cite this article as ▼
Soumitra Ghara, Rajeev Gupta, Md. Ramiz Reza, Cesàro summability of Taylor series in higher order weighted Dirichlet-type spaces, Opuscula Math. 44, no. 3 (2024), 373-390,
https://doi.org/10.7494/OpMath.2024.44.3.373.
Download this article's citation as: