Goal:
  
  G : t
  s0 : VSet.t
  s' : VSet.t
  x : V.t
  y : V.t
  z : V.t
  d : DisjointAdd x s0 s'
  e : EdgeOf x y
  p : SPath s0 y z
  IHp : forall s' : VSet.t, VSet.Subset s0 s' -> SPath s' y z
  s'0 : VSet.t
  Hs : VSet.Subset s' s'0
  u : VSet.elt
  Hu : VSet.In u s0
  ============================
   (x = u \/ VSet.In u s0)


DEBUG:Going to execute:
match reverse goal with
           | id:(?X1 -> ?X2) -> ?X3
             |- _ =>
                 Ltac.cut X3;
                  [ intro; clear id; t_tauto_intuit
                  | Ltac.cut (X1 -> X2);
                     [ exact
                     id
                     | generalize (fun y : X2 => id (fun x : X1 => y)); intro;
                        clear id; (solve [ t_tauto_intuit ]) ] ]
           | id:~ ?X1 -> ?X3
             |- _ =>
                 Ltac.cut X3;
                  [ intro; clear id; t_tauto_intuit
                  | Ltac.cut (~ X1);
                     [ exact
                     id
                     | clear id; intro; (solve [ t_tauto_intuit ]) ] ]
           | |- ?X1 =>
                 <Coq.Init.Tauto.is_disj> flags X1; (solve
                  [ Ltac.left; t_tauto_intuit | Ltac.right; t_tauto_intuit ])
           end ||
             match goal with
             | |- _ -> _ => intro; t_tauto_intuit
             | |- _ => t_reduce; t_solver
             end || t_solver
Level 3: Backtrace:

No such assumption.
Level 2: Backtrace:

No such assumption.
Level 1: Backtrace:

No such assumption.
Level 1: evaluation raised the exception
Backtrace:

No such assumption.

Level 1: Backtrace:

No such assumption.
Level 0: Backtrace:

No such assumption.