Finite interpolation with minimum uniform norm in C-n

Citation
E. Amar et Pj. Thomas, Finite interpolation with minimum uniform norm in C-n, J FUNCT ANA, 170(2), 2000, pp. 512-525
Citations number
16
Categorie Soggetti
Mathematics
Journal title
JOURNAL OF FUNCTIONAL ANALYSIS
ISSN journal
00221236 → ACNP
Volume
170
Issue
2
Year of publication
2000
Pages
512 - 525
Database
ISI
SICI code
0022-1236(20000201)170:2<512:FIWMUN>2.0.ZU;2-I
Abstract
Given a finite sequence a := {a(1), ..., a(N)} in a domain Omega subset of C-n, and complex scalars r:= {r(1), ..., r(N)}, consider the classical extr emal problem of finding the smallest uniform norm of a holomorphic function integral(a(t)) = r(integral) for all integral. We show that the modulus of the solutions to this problem must approach its least upper hound along a subset of the boundary of the domain large enough KI that its A(Omega)-hull contains a subset of the original a large enough to force the same minimum norm. Furthermore, all the solutions must agree on a variety which contain s the hull (in an appropriate, weaker, sense) of a measure supported on the maximum modulus set. An example is given to show that the inclusions can b e strict, (C) 2000 Academic Press.