OPTIMAL INTERIOR PARTIAL REGULARITY FOR NONLINEAR ELLIPTIC SYSTEMS UNDER THE NATURAL GROWTH CONDITION:THE METHOD OF A-HARMONIC APPROXIMATION

In this article,the authors consider the nonlinear elliptic systems under the natural growth condition.They use a new method introduced by Duzaar and Grotowski, for proving partial regularity for weak solutions,based on a generalization of the technique of harmonic approximation.And directly establish the optimal Holder exponent for the derivative of a weak solution.