Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  y_0 : V.t
  x_0 : V.t
  Vx : VSet.In x_0 (V G)
  Vy : VSet.In y_0 (V G)
  Hxs : lsp G x_0 y_0 = None
  K : Z
  ============================
   ((y_0, ?k, x_0) = (y_0, K, x_0) \/ EdgeSet.In (y_0, ?k, x_0) (E G))


DEBUG:Going to execute:
left
Level 1: Backtrace:

No such assumption.
Level 0: Backtrace:

No such assumption.
DEBUG LTAC Evaluated term: EdgeSet.add_spec