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On equidistant sets in normed linear spaces

Published online by Cambridge University Press:  17 April 2009

B.B. Panda
Affiliation:
Department of Mathematics, Indian Institute of Technology Kanpur, Kanpur, India.
O.P. Kapoor
Affiliation:
Department of Mathematics, Indian Institute of Technology Kanpur, Kanpur, India.
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Abstract

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In this note some results concerning the equidistant set E(−x, x) and the kernel Mθ of the metric projection PM, where M is a Chebyshev subspace of a normed linear space X, have been obtained. In particular, when X = lp (1 < p < ∞), it has been proved that every equidistant set is closed in the bw-topology of the space. In c0 no equidistant set has this property.

Type
Research Article
Copyright
Copyright © Australian Mathematical Society 1974

References

[1]Day, Mahlon M., “Some characterizations of inner-product spaces”, Trans. Amer. Math. Soc. 62 (1947), 320337.CrossRefGoogle Scholar
[2]Holmes, R.B., “On the continuity of best approximation operators”, Symposium on infinite dimensional theory, 137157 (Annals of Mathematics Studies, 69. Princeton University Press and University of Tokyo Press, Princeton, New Jersey, 1972).CrossRefGoogle Scholar
[3]Holmes, Richard B., A course on optimization and beet approximation (Lecture Notes in Mathematics, 257. Springer-Verlag, Berlin, Heidelberg, New York, 1972).CrossRefGoogle Scholar
[4]Holmes, Richard and Kripke, Bernard, “Smoothness of approximation”, Michigan Math. J. 15 (1968), 225248.CrossRefGoogle Scholar
[5]James, R.C., “Orthogonality in normed linear spaces”, Duke Math. J. 12 (1945), 291302.CrossRefGoogle Scholar
[6]Kalisch, G.K. and Straus, E.G., “On the determination of points in a Banach space by their distances from the points of a given set”, An. Acad. Brasil. Ci. 29 (1957), 501519.Google Scholar
[7]Klee, Victor, “Convexity of Chebyshev sets”, Math. Ann. 142 (1961), 292304.CrossRefGoogle Scholar
[8]Kottman, Clifford A. and Lin, Bor-Luh, “The weak continuity of metric projections”, Michigan Math. J. 17 (1970), 401404.CrossRefGoogle Scholar
[9]Lambert, Joseph Michael, “The weak sequential continuity of the metric projection in Lp spaces”, (Dissertation, Purdue University, 1970).Google Scholar