Goal:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : Edge.t
  s : VSet.t
  _b_ : x = e..t
  _b1_ : VSet.In x (V G1)
  ============================
   (x = e..s /\ VSet.In x (V G1) \/
    x = e..t /\ VSet.In x (V G1) \/ VSet.In x s)


DEBUG:Going to execute:
Ltac.right; t_tauto_intuit
Level 2: Backtrace:

Proof is not complete.
Level 2: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 2: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 2: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 2: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 2: Backtrace:

Proof is not complete.
Level 2: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 3: Backtrace:

Proof is not complete.
Level 2: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 2: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.