Goal:
  
  A : Type
  P : nat → A → Type
  p : nat → A → bool
  n : nat
  Hp : ∀ (i : nat) (x : A), reflectT (P i x) (p i x)
  H : is_true true
  ============================
   (Alli P n [])


DEBUG:Going to execute:
do
![ solve
 [ trivial | apply : eq_sym ; trivial ]
 | discriminate
 | contradiction
 | Ltac.split ]