Konstanta James

Hendra Gunawan

Diberikan suatu ruang Banach (X,\|\cdot\|), konstanta James adalah sebuah bilangan yang mengukur ketakpersegian seragam X, yang didefinisikan sebagai

C_{\rm J}(X) :=\sup\{\min \{\|x+y\|,\|x-y\|\}\,:\,\|x\|=\|y\|=1\}.

Berdasarkan definisi ketakpersegian seragam yang dibahas hari Sabtu yang lalu, ruang Banach X tak persegi seragam jika dan hanya jika C_{\rm J}(X)\le 2(1-\delta) < 2.

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Bandung, 03-08-2019

Published by Hendra Gunawan

I'm a professor of mathematics at the Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Bandung, Indonesia.

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