On uniqueness properties of solutions of the k-generalized KdV equations
  In this paper we study uniqueness properties of solutions of the k-generalized Korteweg-de Vries equation.   Our goal is to obtain sufficient conditions on the behavior of the difference $u_1-u_2$ of two solutions $u_1, u_2$ of the equation at two different times $t_0=0$ and $t_1=1$ which guarantee that $u_1\equiv u_2$. 
Luis Escauriaza, Carlos E. Kenig, Gustavo Ponce, and Luis Vega