DOUBLE BEST APPROXATION RELATIVE TO TWO CLOSED SETS

In this research, PA(B), BP(A), P(A,B) for two closed subsets of normed space X and normality of A relative to B are defined. Also, the best approximation of a subset normal on a subset of X, and double best approximation are verfied.

Keywords:

Double proximinal , Double Chebyshev , Normal set , Double best approximation