Bull. Korean Math. Soc. 2008 Vol. 45, No. 3, 601-606 Printed September 1, 2008
Maram Shams, Hamid Mazaheri, and Sayed Mansour Vaezpour Yazd University, Yazd University, Yazd University
Abstract : The purpose of this paper is to introduce and discuss the concept of $w$-Chebyshev subspaces in Banach spaces. The concept of quasi Chebyshev in Banach space is defined. We show that $w$-Chebyshevity of subspaces are a new class in approximation theory. In this paper, also we consider orthogonality in normed spaces.