dist-FORMULAS AND TOEPLITZ OPERATORS

GÜRDAL M. , GARAYEV M. T. , SALTAN S. , YAMANCI U.

ANNALS OF FUNCTIONAL ANALYSIS, vol.6, no.1, pp.221-226, 2015 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 6 Issue: 1
  • Publication Date: 2015
  • Doi Number: 10.15352/afa/06-1-16
  • Title of Journal : ANNALS OF FUNCTIONAL ANALYSIS
  • Page Numbers: pp.221-226

Abstract

The distance from the nonconstant function phi in L-infinity(T) to the set F-const of all constant functions is estimated in terms of Hankel operators on the Hardy space H-2(D) over the unit disk D = {z is an element of C : \z\ < 1}. We give a sufficient condition ensuring the equality dist(phi, F-const) = ||phi||(L infinity). Some other dist-formulas are also discussed.