Goal:
  
  A : Type
  P : list A → A → Type
  Q : list A → A → Type
  d : A
  Γ : list A
  X : All_fold P Γ
  p : P Γ d
  IHX : (∀ (Γ : list A) (x : A), P Γ x → Q Γ x) → All_fold Q Γ
  X0 : ∀ (Γ : list A) (x : A), P Γ x → Q Γ x
  ============================
   (All_fold Q (d :: Γ))


DEBUG:Going to execute:
<coq-core.plugins.ltac::discriminate@0>
Level 0: Backtrace:

Cannot apply lemma eq_sym
Level 0: Backtrace:

Cannot apply lemma eq_sym
Level 0: Backtrace:

Cannot apply lemma eq_sym