Goal:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  v : VSet.elt
  s : VSet.t
  __view_subject_1_ : VSet.In v (V G1)
  H0 : VSet.E.eq x v
  ============================
   (x = v /\ VSet.In x (V G1) \/ VSet.In x s)


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

Failed to progress.