Goal:
  
  A : Type
  P : nat → A → Type
  n : nat
  hd : A
  tl : list A
  p : P n hd
  X : Alli P (S n) tl
  IHX : All_fold (λ (Γ : list A) (d : A), P (S n + #|Γ|) d) (List.rev tl)
  ============================
   (∀ (Γ : list A) (x : A),
      (λ (Γ0 : list A) (d : A), P (S n + #|Γ0|) d) Γ x
      → P (n + #|Γ ++ [hd]|) x)


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

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.