Approximation and Uniqueness for -Harmonic Functions

 In this paper, we consider the class of functions defined on the unit ball which are harmonic with respect to a certain class of degenerate elliptic operators. We establish some approximation and uniqueness theorems for these functions. Our work generalizes some recent results obtained by J. Bruna and K. T. Hahn in the particular case of the Laplace-Beltrami operator of the Bergman metric. (Received 17 September 1998)