A Probabilistic Characterization of g-Harmonic Functions

This paper gives a definition of g-harmonic functions and shows the relation between the g-harmonic functions and g-martingales. It’s direct to construct such relation under smooth case, but for continuous case we need the theory of viscosity solution. The results show that under the nonlinear expectation mechanism, we also can get the similar relation between harmonic functions and martingales. Finally, we will give a result about the strict converse problem of mean value property of g-harmonic functions.