N-soliton solutions of the KP equation by Exp-function method

In this paper, the Exp-function method is generalized to determine the 1-soliton, 2-soliton and 3-soliton solutions of the Kadomtsev-Petviashvili (KP) equation. Then the uniform formula of N-soliton solutions is derived. The method is simple and straightforward in constructing the N-soliton of the nonlinear evolution equation in mathematical physics.