Goal:
  
  A : Type
  P : list A → A → Type
  Q : list A → list A → A → A → Type
  hlen : #|[]| = #|[]|
  H : ∀ (Δ Δ' : list A) (x y : A),
        All_fold P Δ
        → All_fold P Δ' → All2_fold Q Δ Δ' → P Δ x → P Δ' y → Q Δ Δ' x y
  ============================
   (All2_fold Q [] [])


DEBUG:Going to execute:
case not_locked_false_eq_true; Ltac.assumption
Level 1: Backtrace:

Not an inductive goal with 1 constructor.
Level 0: Backtrace:

Not an inductive goal with 1 constructor.
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.