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On the average distance property in finite dimensional real Banach spaces

Published online by Cambridge University Press:  17 April 2009

Reinhard Wolf
Affiliation:
Institute fur MathematikUniversitat SalzburgHellbrunneratrasse 34 A-5020 Salzburg, Austria
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Abstract

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The average distance Theorem of Gross implies that for each N-dimensional real Banach space E (N ≥ 2) there is a unique positive real number r(E) with the following property: for each positive integer n and for all (not necessarily distinct) x1, x2, …, xn, in E with ‖x1‖ = ‖x2‖ = … = ‖xn‖ = 1, there exists an x in E with ‖x‖ = 1 such that

.

In this paper we prove that if E has a 1-unconditional basis then r(E)≤2−(l/N) and equality holds if and only if E is isometrically isomorphic to Rn equipped with the usual 1-norm.

Type
Research Article
Copyright
Copyright © Australian Mathematical Society 1995

References

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