Symmetry Reductions and Explicit Solutions of( 3 + 1)-dimensional Generalized Kadomtsev-Petviashvili Equation

With the aid of symbolic computation,we use the classical Lie group method to find symmetry reductions of( 3 + 1)- dimensional generalized Kadomtsev- Petviashvili( KP) equation,and present five types of new symmetry reduction equations. Based on the Exp- function method,we obtain the explicit solution of the equation with an arbitrary function by considering similar variables. The method is quite effective to high- dimensional differential equations,and can get more explicit solutions.