Abstract
If the Poisson integral of the unit disc is replaced by its square root, it is known that normalized Poisson integrals of L p and weak L p boundary functions converge along approach regions wider than the ordinary nontangential cones, as proved by Rönning and the author, respectively. In this paper we characterize the approach regions for boundary functions in two general classes of Orlicz spaces. The first of these classes contains spaces L Φ having the property L ∞ ⊂ L Φ L p, 1 ⩽ p > ∞. The second contains spaces L Φ that resemble L p spaces.
Similar content being viewed by others
References
H. Aikawa: Harmonic functions having no tangential limits. Proc. Am. Math. Soc. 108 (1990), 457–464.
A. Bellow, R. L. Jones: A Banach principle for L ∞. Adv. Math. 120 (1996), 155–172.
M. Brundin: Approach regions for the square root of the Poisson kernel and weak L p boundary functions. Preprint 1999:56. Department of Mathematics, Göteborg University and Chalmers University of Technology, 1999.
M. Brundin: Approach Regions for L p potentials with respect to fractional powers of the Poisson rernel of the halfspace. Department of Mathematics. Göteborg University and Chalmers University of Technology, 2001.
M. Brundin: Approach regions for L p potentials with respect to the square root of the Poisson kernel. Math. Scand. To appear.
F. Di Biase: Fatou Type Theorems: Maximal Functions and Approach Regions. Birkhäuser-Verlag, Boston, 1998.
P. Fatou: Séries trigonométriques et séries de Taylor. Acta Math. 30 (1906), 335–400.
J. E. Littlewood: On a theorem of Fatou. J. London Math. Soc. 2 (1927), 172–176.
A. Nagel, E. M. Stein: On certain maximal functions and approach regions. Adv. Math. 54 (1984), 83–106.
M. M. Rao, Z. D. Ren: Theory of Orlicz Spaces. Monographs and Textbooks in Pure and Applied Mathematics, Vol. 146. Marcel Dekker, New York, 1991.
J.-O. Rönning: Convergence results for the square root of the Poisson kernel. Math. Scand. 81 (1997), 219–235.
H. A. Schwarz: Zur Integration der partiellen Differentialgleichung \(\frac{{\partial ^2 u}}{{\partial x^2 }} + \frac{{\partial ^2 u}}{{\partial y^2 }} = 0\). J. Reine Angew. Math. 74 (1872), 218–253.
P. Sjögren: Une remarque sur la convergence des fonctions propres du laplacien à valeur propre critique. In: Théorie du potentiel (Orsay, 1983). Springer-Verlag, Berlin, 1984, pp. 544–548.
P. Sjögren: Approach regions for the square root of the Poisson kernel and bounded functions. Bull. Austral. Math. Soc. 55 (1997), 521–527.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Brundin, M. Approach regions for the square root of the Poisson kernel and boundary functions in certain Orlicz spaces. Czech Math J 57, 345–365 (2007). https://doi.org/10.1007/s10587-007-0064-6
Received:
Issue Date:
DOI: https://doi.org/10.1007/s10587-007-0064-6