Goal:
  
  A : Type
  p : nat → A → bool
  n : nat
  l : list A
  f : Alli (λ (x : nat) (x0 : A), p x x0) n l → False
  H : is_true false
  ============================
   (Alli (λ (x : nat) (x0 : A), p x x0) n l)


DEBUG:Going to execute:
solve
[ do
![ solve
 [ trivial | apply : eq_sym ; trivial ]
 | discriminate
 | contradiction
 | Ltac.split ]
| case not_locked_false_eq_true; Ltac.assumption
| match goal with
  | H:¬ _ |- _ => solve [ case H; trivial ]
  end ]