“…The invariance properties of some of the integrable nonlinear evolution equations in (2+1)-dimensions, which are very important in mathematics and physics, have been studied through the classical Lie group approaches. For instance, the Kadomatsev-Petvishilli equation, [15] the Davey-Stewartson equation, [16] the three-wave interaction problem, [17] the cylindrical Kadomtsev-Petviashvilli equation, [18] the stimulated Raman scattering equation, [19] the Nizhnik-Novikov-Veselov equation, the breaking soliton equation, the sine-Gordon system, [20] and the long dispersive wave equation, [21,22] etc. The related symmetry groups can be obtained by means of * The project supported by National Natural Science Foundation of China under Grant No.…”