Goal:
    y1 : V.t  x2 : V.t  n2 : Z  y2 : V.t  H : V.lt y2 y1
  ============================
   (V.lt x2 x2)


DEBUG:Going to execute:
match goal with
           | |- _ -> _ => intro; t_tauto_intuit
           | |- _ => t_reduce; t_solver
           end