The Existence of Non-Trivial Bounded Functionals Implies the Hahn-Banach Extension Theorem
Martin Väth
Czech Academy of Sciences, Prague, Czech RepublicW.A.J. Luxemburg
California Institute of Technology, Pasadena, USA

Abstract
We show that it is impossible to prove the existence of a linear (bounded or unbounded) functional on any _\{infty}/C_0 without an uncountable form of the axiom of choice. Moreover, we show that if on each Banach space there exists at least one non-trivial bounded linear functional, then the Hahn-Banach extension theorem must hold. We also discuss relations of non-measurable sets and the Hahn-Banach extension theorem.
Cite this article
Martin Väth, W.A.J. Luxemburg, The Existence of Non-Trivial Bounded Functionals Implies the Hahn-Banach Extension Theorem. Z. Anal. Anwend. 20 (2001), no. 2, pp. 267–279
DOI 10.4171/ZAA/1015