Integrable Discretization of Soliton Equations via Bilinear Method and   B\"acklund Transformation
  In this paper, we present a systematic procedure to derive discrete analogues of integrable PDEs via Hirota's bilinear method. This approach is mainly based on the compatibility between an integrable system and its B\"acklund transformation. We apply this procedure to several equations, including the extended Korteweg-de-Vries (KdV) equation, the extended Kadomtsev-Petviashvili (KP) equation, the extended Boussinesq equation, the extended Sawada-Kotera (SK) equation and the extended Ito equation, and obtain their associated semi-discrete analogues. In the continuum limit, these differential-difference systems converge to their corresponding smooth equations. For these new integrable systems, their B\"acklund transformations and Lax pairs are derived 
Yingnan Zhang, Xiangke Chang, Juan Hu, Xingbiao Hu and Hon-Wah Tam
math-ph math.DS math.MP