Bull. Austral. Math. Soc. 72(2) pp.299--315, 2005.

Proper 1-ball contractive retractions in
Banach spaces of measurable functions

D. Caponetti

A. Trombetta

G. Trombetta

Received: 5th May, 2005



In this paper we consider the Wośko problem of evaluating, in an infinite-dimensional Banach space X, the infimum of all k$ \ge $1 for which there exists a k-ball contractive retraction of the unit ball onto its boundary. We prove that in some classical Banach spaces the best possible value 1 is attained. Moreover we give estimates of the lower H-measure of noncompactness of the retractions we construct.

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(Metadata: XML, RSS, BibTeX) MathSciNet: MR2183411 Z'blatt-MATH: 02246392


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