Abstract.
It is shown that if (λ n ) is a sequence of distinct points on the unit circle, then, for a sequence (a n ) of points in the closed unit disk, there exists an interpolating Blaschke product B with B*(λ n )=a n for all n if and only if (a n ) is bounded away from zero. This complements results of Cargo, Carroll, Colwell, Belna and Piranian on prescribing radial limits for Blaschke products.
Similar content being viewed by others
References
Belna, C., Carroll, F., Piranian, G.: Strong Fatou-1-points of Blaschke products. Trans. Amer. Math. Soc. 280, 695–702 (1983)
Belna, C., Colwell, P., Piranian, G.: The radial behavior of Blaschke products. Proc. Amer. Math. Soc. 93, 267–271 (1985)
Berman, R., Nishiura, T.: Interpolation for inner functions on dispersed subsets of the unit circle. J. London Math. Soc. 38, 463–484 (1988)
Berman, R., Nishiura, T.: Some mapping properties of the radial limit function of an inner function. J. London Math. Soc. 52, 375–390 (1995)
Cantor, D., Phelps, R.: An elementary interpolation theorem. Proc. Amer. Math. Soc. 16, 523–525 (1965)
Cargo, G.: Blaschke products and singular inner functions with prescribed boundary values. J. Math. Analysis Appl. 71, 287–296 (1979)
Carleson, L.: An interpolation problem for bounded analytic functions. Amer. J. Math. 80, 921–930 (1958)
Daepp, U., Gorkin, P., Mortini, R.: Ellipses and finite Blaschke products. Amer. Math. Monthly 109, 785–795 (2002)
Earl, J.P.: On the interpolation of bounded sequences by bounded functions. J. London Math. Soc. 2, 544–548 (1970)
Garnett, J.: Bounded Analytic Functions. Academic Press, New York 1981
Glader, C., Lindström, M.: Finite Blaschke product interpolation on the closed unit disc. J. Math. Anal. Appl. 273, 417–427 (2002)
Gorkin, P., Laroco, L., Mortini, R., Rupp, R.: Composition of inner functions. Results in Math. 25, 252–269 (1994)
Gorkin, P., Mortini, R.: Cluster sets of interpolating Blaschke products. Preprint
Gorkin, P., Mortini, R.: Value distribution of interpolating Blaschke products. Preprint
Hoffman, K.: Bounded analytic functions and Gleason parts. Ann. Math. 86, 74–111 (1967)
Jones, W., Ruscheweyh, S.: Blaschke product interpolation and its application to the design of digital filters. Constr. Approx. 3, 405–409 (1987)
Kerr-Lawson, A.: Some lemmas on interpolating Blaschke products and a correction. Canad. J. Math. 21, 531–534 (1969)
Mortini, R., Nicolau, A.: Frostman shifts of inner functions, to appear in J. d’Analyse Math.
Nicolau, A.: Blaschke products with prescribed radial limits. Bull. London Math. Soc. 23, 249–255 (1991)
Nicolau, A.: Interpolating Blaschke products solving Pick-Nevanlinna problems. J. d’Analyse Math. 62, 199–224 (1994)
Sarason, D.: Nevanlinna-Pick interpolation with boundary data. Integral Equations Operator Theory 30, 231–250 (1998)
Younis, R.: Interpolation by a finite Blaschke product. Proc. Amer. Math. Soc. 78, 451–452 (1980)
Wolff, T.: Some theorems on vanishing mean oscillation. PH. D.Thesis, Univ. of California, Berkeley, 1979
Author information
Authors and Affiliations
Corresponding author
Additional information
Mathematics Subject Classification (2000): 30D50
Revised version: 1 June 2004
Acknowledgment The authors thank the Mathematisches Forschungsinstitut Oberwolfach for the support and for the kind hospitality they always receive. The work presented here is part of their 2002–2004 project “Inner functions”. The first author also thanks Universität Bern where she spent her sabbatical, as well as Université de Metz, where she was “professeur invité” for one month. The second author presented this work in May 2004 at the fourth congress of the European network “Analysis and Operators” in Dalfsen, the Netherlands. He gratefully acknowledges the support he received from the European community’s human potential program, contract HPRN-CT-2000-00116.
Rights and permissions
About this article
Cite this article
Gorkin, P., Mortini, R. Radial limits of interpolating Blaschke products. Math. Ann. 331, 417–444 (2005). https://doi.org/10.1007/s00208-004-0588-0
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00208-004-0588-0