“…In recent years, many methods have been found to solve the exact solutions of soliton equations. For example, Hirota bilinear method [16][17][18], Generalized bilinear method [19,20], homogeneous balance method [21,22], Riemann-Hilbert method [23][24][25], Darboux transformation [26][27][28], Riccati expansion method [29,30] and so on. Hirota bilinear method is a common method to solve soliton equations, and Ma has solved many soliton equations with lump solutions and exact solutions by Hirota bilinear method [31].…”