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Weak Type Estimates of the Maximal Quasiradial Bochner-Riesz Operator On Certain Hardy Spaces

Published online by Cambridge University Press:  20 November 2018

Yong-Cheol Kim*
Affiliation:
Department of Mathematics Education, Korea University, Seoul 136-701, Korea, e-mail: ychkim@korea.ac.kr
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Abstract

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Let ${{\left\{ {{A}_{t}} \right\}}_{t>0}}$ be the dilation group in ${{\mathbb{R}}^{n}}$ generated by the infinitesimal generator $M$ where ${{A}_{t}}\,=\,\exp \left( M\,\log \,t \right)$, and let $\varrho \,\in \,{{C}^{\infty }}\left( \mathbb{R}{{}^{n\,}}\backslash \,\left\{ 0 \right\} \right)$ be a ${{A}_{t}}$-homogeneous distance function defined on ${{\mathbb{R}}^{n}}$. For $f\,\in \,\mathfrak{S}\left( \mathbb{R}{{}^{n}} \right)$, we define the maximal quasiradial Bochner-Riesz operator $\mathfrak{M}_{\varrho }^{\delta }$ of index $\delta \,>\,0$ by

$$\mathfrak{M}_{\varrho }^{\delta }f\left( x \right)\,=\,\underset{t>0}{\mathop{\sup }}\,\left| {{\mathcal{F}}^{-1}}\left[ \left( 1-{\varrho }/{t}\; \right)_{+}^{\delta }\hat{f} \right]\left( x \right) \right|.$$

If ${{A}_{t\,}}=\,tI$ and $\left\{ \xi \,\in \,{{\mathbb{R}}^{n\,}}\,|\,\varrho \left( \xi \right)\,=\,1 \right\}$ is a smooth convex hypersurface of finite type, then we prove in an extremely easy way that $\mathfrak{M}_{\varrho }^{\delta }$ is well defined on ${{H}^{p}}\left( {{\mathbb{R}}^{n}} \right)$ when $\delta \,=\,n(1/p\,-\,1/2)\,-\,1/2$ and $0\,<\,p\,<\,1$; moreover, it is a bounded operator from ${{H}^{p}}\left( {{\mathbb{R}}^{n}} \right)$ into ${{L}^{p,\infty }}\left( {{\mathbb{R}}^{n}} \right)$ .

If ${{A}_{t}}\,=\,tI$ and $\varrho \,\in \,{{C}^{\infty }}\left( \mathbb{R}{{}^{n\,}}\backslash \,\left\{ 0 \right\} \right)$ , we also prove that $\mathfrak{M}_{\varrho }^{\delta }$ is a bounded operator from ${{H}^{p}}\left( {{\mathbb{R}}^{n}} \right)$ into ${{L}^{p}}\,\left( {{\mathbb{R}}^{n}} \right)$ when $\delta \,>\,n(1/p\,-\,1/2)\,-\,1/2$ and $0\,<\,p\,<\,1$.

Keywords

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 2003

References

[1] Bruna, J., Nagel, A. and Wainger, S. Convex hypersurfaces and Fourier transforms. Ann. of Math. 127 (1988), 333365.Google Scholar
[2] Córdoba, A., A note on Bochner-Riesz operators. Duke Math. J. 46 (1979), 505511.Google Scholar
[3] Dappa, H. and Trebels, W., On maximal functions generated by Fourier multipliers. Ark. Mat. 23 (1985), 241259.Google Scholar
[4] Kim, Y.-C., Almost everywhere convergence of quasiradial Bochner-Riesz means. J. Math. Anal. Appl. 232 (1999), 332346.Google Scholar
[5] Kim, Y.-C., Fourier transform on nonsmooth surface measure and its applications. Unpublished manuscript.Google Scholar
[6] Kim, Y. and Seeger, A., A note on pointwise convergence of quasiradial Riesz means. Acta Sci. Math. (Szeged) 62 (1996), 187199.Google Scholar
[7] Randol, B., On the asymptotic behavior of the Fourier transform of the indicator function of a convex set. Trans. Amer. Math. Soc. 139 (1969), 279285.Google Scholar
[8] Seeger, A., Estimates near L1 for Fourier multipliers and maximal functions. Arch. Math. 53 (1989), 188193.Google Scholar
[9] Stein, E. M., Harmonic Analysis; Real variable methods, orthogonality, and oscillatory integrals. Princeton Univ. Press, 1993.Google Scholar
[10] Stein, E. M., Taibleson, M. H. and Weiss, G., Weak type estimates for maximal operators on certain Hp classes. Rend. Circ. Mat. Palermo Suppl. 1 (1981), 8197.Google Scholar
[11] Stein, E. M. and Wainger, S., Problems in harmonic analysis related to curvature. Bull. Amer.Math. Soc. 84 (1978), 12391295.Google Scholar
[12] Stein, E. M. and Weiss, G., Introduction to Fourier Analysis on Euclidean Spaces. Princeton Univ. Press, New Jersey, 1971.Google Scholar
[13] Svensson, I., Estimates for the Fourier transform of the characteristic function of a convex set. Ark. Mat. 9 (1971), 1122.Google Scholar