Best Co-approximation and Worst Approximation by Closed Unit Balls

‎A kind of approximation‎, ‎called best coapproximation was‎ introduced and discussed in normed linear spaces by C‎. ‎Franchetti and M‎. Furi in ۱۹۷۲‎. ‎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.

کلیدواژه ها:

‎Copoximinal‎ ، ‎Cochebyshevl‎ ، ‎ ‎Uniquely remotal‎ ، ‎Qcoproximinal‎ ، ‎Closed Unit Balls