Best Simultaneous Approximation of Functions and a Generalized Minimax Theorem

Abstract

Best simultaneous approximation (BSA) for finitely or infinitely many functions are considered under the uniform norm and other important norms. Characterization theorems for a BSA from a finite-dimensional subspace are obtained by a generalized minimax theorem. From the characterization theorem a strong unicity theorem is also deduced for a BSA.

8 pages