Goal:
  
  A : Type
  sizeA : A → nat
  B : Type
  sizeB : B → nat
  l : list A
  f : nat → A → B
  H : ∀ (i : nat) (x : A), sizeB (f i x) ≤ sizeA x
  ============================
   (∀ (i : nat) (x : A), sizeB (f i x) ≤ sizeA x)


DEBUG:Going to execute:
solve [ do_atom | use_hyps; do_ccl ]