Goal:
  
  A : Type
  B : Type
  R : A → B → Type
  R' : ∀ (a : A) (b : B), R a b → Type
  x : A
  y : B
  l : list A
  l' : list B
  r : R x y
  rs : All2 R l l'
  r0 : R' x y r
  a0 : All2_dep R' rs
  ============================
   (let H := CoreTactics.block in
    let H0 := CoreTactics.block in
    noConfusionHom_All2_dep_obligation_1 A B R R' 
      (x :: l) (y :: l') (All2_cons r rs) (All2_dep_cons r0 a0)
      (All2_dep_cons r0 a0)
      (noConfusionHom_All2_dep_obligation_2 A B R R' 
         (x :: l) (y :: l') (All2_cons r rs) (All2_dep_cons r0 a0)
         (All2_dep_cons r0 a0) eq_refl) = eq_refl)


DEBUG:Going to execute:
DepElim.simplify_one_dep_elim
Level 5: Backtrace:

Tactic failure (level 1).
Level 4: Backtrace:

Tactic failure.
Level 3: Backtrace:

Tactic failure.