Goal:
  
  A : Type
  B : Type
  C : Type
  R : A → B → C → Type
  x : A
  y : B
  z : C
  l : list A
  l' : list B
  l'' : list C
  r : R x y z
  a : All3 R l l' l''
  b : All3 R (x :: l) (y :: l') (z :: l'')
  ============================
   (∀ (H := CoreTactics.block) (e : NoConfusionHom_All3 A B C R 
                                      (x :: l) (y :: l') 
                                      (z :: l'') (All3_cons r a) b),
      let H0 := CoreTactics.block in
      noConfusionHom_All3_obligation_2 A B C R (x :: l) 
        (y :: l') (z :: l'') (All3_cons r a) b
        (noConfusionHom_All3_obligation_1 A B C R 
           (x :: l) (y :: l') (z :: l'') (All3_cons r a) b e) = e)


DEBUG:Going to execute:
progress (autounfold with equations in e; simpl in e)
Level 2: Backtrace:

Failed to progress.
Level 2: Backtrace:

Failed to progress.
Level 2: Backtrace:

Failed to progress.
Level 2: Backtrace:

Failed to progress.
Level 2: Backtrace:

Failed to progress.