Best Co-approximation and Worst Approximation by Closed Unit Balls

الموضوعات :

Hamid Tehrani ¹ (Department of Mathematics, Yazd University, Yazd, Iran)

تاريخ الإرسال : 16 الخميس , ربيع الثاني, 1444 تاريخ التأكيد : 20 الأربعاء , جمادى الأولى, 1444 تاريخ الإصدار : 05 السبت , ربيع الأول, 1444

الکلمات المفتاحية: ‎Copoximinal‎, ‎Closed Unit Balls, ‎Qcoproximinal‎, ‎ ‎Uniquely remotal‎, ‎Cochebyshevl‎,

ملخص المقالة :

‎A kind of approximation‎, ‎called best coapproximation was‎ introduced and discussed in normed linear spaces by C‎. ‎Franchetti and M‎. Furi in 1972‎. ‎Subsequently‎, ‎this study was taken up by several researchers‎ in different abstract spaces‎. In this paper‎, ‎we consider best coapproximation by closed unit balls‎. ‎We define qcoproximinal and coremotal‎, ‎and find some theorems.