Interaction of Three Waves for the Extension(2+1)-Dimensional Sine-Gordon Equation

Exact solutions with three-wave form including three solitary wave, breather-type two-solitary wave, doubly breather-type of solitary wave, double-periodic kind of solitary wave are obtained using bilinear form and extended threewave approach with the aid of Maple. It is important that completed elastic collision, non-completed elastic collision,and fusion of three waves are investigated, respectively.