Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  n : Z
  x : V.t
  y : V.t
  n0 : (Some n <= lsp G x (s G))%nbar -> False
  H : false = true
  ============================
   (Some n <= lsp G x (s G))%nbar


DEBUG:Going to execute:
t_solver
Level 0: Backtrace:

Failed to progress.