Available in electronic format
Available in print format
Proceedings of the American Mathematical Society
Proceedings of the American Mathematical Society
ISSN 1088-6826 (e) ISSN 0002-9939 (p)
     

Infinite dimensional universal subspaces generated by Blaschke products

Author(s): Raymond Mortini
Journal: Proc. Amer. Math. Soc. 135 (2007), 1795-1801.
MSC (2000): Primary 30D50; Secondary 47B33, 46J15, 30H05
Posted: December 28, 2006
Retrieve article in: PDF DVI PostScript

Abstract | References | Similar articles | Additional information

Abstract: Let $ H^\infty$ be the Banach algebra of all bounded analytic functions in the unit disk $ \mathbb{D}$. A function $ f\in H^\infty$ is said to be universal with respect to the sequence $ (\frac{z+z_n}{1+\overline{z}_nz})_n$ of noneuclidian translates, if the set $ \{f(\frac{z+z_n}{1+\overline {z}_nz}):n\in\mathbb{N}\}$ is locally uniformly dense in the set of all holomorphic functions bounded by $ \vert\vert f\vert\vert _\infty$. We show that for any sequence of points $ (z_n)$ in $ \mathbb{D}$ tending to the boundary there exists a closed subspace of $ H^\infty$, topologically generated by Blaschke products, and linear isometric to $ \ell^1$, such that all of its elements $ f$ are universal with respect to noneuclidian translates. The proof is based on certain interpolation problems in the corona of $ H^\infty$. Results on cyclicity of composition operators in $ H^2$ are deduced.


References:

1.
R. Aron, P. Gorkin: An infinite dimensional vector space of universal functions for $ H^\infty$ on the ball, to appear in Canad. Math. Bull.

2.
P. Bourdon, Shapiro, J. H.: Cyclic phenomena for composition operators. Mem. Amer. Math. Soc. 125 (1997), no. 596, x+105 pp.MR 1396955 (97h:47023)

3.
J.B. Garnett: Bounded Analytic Functions, Academic Press, New York, 1981. MR 0628971 (83g:30037)

4.
P. Gorkin, R. Mortini: Universal Blaschke products, Math. Proc. Camb. Phil. Soc. 136 (2004), 175-184. MR 2034021 (2004m:30056)

5.
K.-G. Grosse-Erdmann: Universal families and hypercyclic operators, Bull. Amer. Math. Soc. 36 (1999), 345-381. MR 1685272 (2000c:47001)

6.
K.-G. Grosse-Erdmann: Recent developments in hypercyclicity, RACSAM Rev. R. Acad. Cienc. Exactas Fis. Nat. Ser. A Mat. 97 (2003), 273-208. MR 2068180 (2005c:47010)

7.
M. Heins: A universal Blaschke product, Archiv Math. 6 (1955), 41-44. MR 0065644 (16:460e)

8.
K. Hoffman: Bounded analytic functions and Gleason parts. Ann. Math. 86 (1967), 74-111. MR 0215102 (35:5945)

Similar Articles:

Retrieve articles in Proceedings of the American Mathematical Society with MSC (2000): 30D50, 47B33, 46J15, 30H05

Retrieve articles in all Journals with MSC (2000): 30D50, 47B33, 46J15, 30H05


Additional Information:

Raymond Mortini
Affiliation: Département de Mathématiques, Université Paul Verlaine, Ile du Saulcy F-57045 Metz, France
Email: mortini@math.univ-metz.fr

DOI: 10.1090/S0002-9939-06-08669-2
PII: S 0002-9939(06)08669-2
Keywords: Universal Blaschke products, interpolation in the corona, composition operators on Hardy spaces, joint cyclic vectors
Received by editor(s): September 6, 2005
Received by editor(s) in revised form: February 5, 2006.
Posted: December 28, 2006
Additional Notes: The author thanks the referee for his/her comments improving the exposition of this work
Communicated by: Joseph A. Ball
Copyright of article: Copyright 2006, American Mathematical Society
The copyright for this article reverts to public domain after 28 years from publication.


  AMS Website Logo Small Comments: webmaster@ams.org
© Copyright 2008, American Mathematical Society
Privacy Statement
Search the AMSPowered by Google