Goal:
  
  A : Type
  P : A → Prop
  Q : A → Prop
  a : A
  l : list A
  a0 : A
  l' : list A
  IHl : ∀ l' : list A,
          All P l
          → All Q l' → #|l| = #|l'| → All2 (λ x y : A, P x ∧ Q y) l l'
  X : All P (a :: l)
  X0 : All Q (a0 :: l')
  H : S #|l| = S #|l'|
  ============================
   (All2 (λ x y : A, P x ∧ Q y) (a :: l) (a0 :: l'))


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.