Virasoro type algebraic structure hidden in the constrained discrete KP   hierarchy
  In this paper, we construct the additional symmetries of one-component constrained discrete KP (cdKP) hierarchy, and then prove that the algebraic structure of the symmetry flows is the positive half of Virasoro algebra. 
Maohua Li and Chuanzhong Li and Keilei Tian and Jingsong He and Yi   Cheng
nlin.SI