Goal:
  
  A : Type
  f : nat → A
  i : nat
  hf : ∀ i j : nat, f i = f j → i = j
  IHn : In (f i) (unfold i f) → i < i
  ============================
   (i < S i)


DEBUG:Going to execute:
<coq-core.plugins.ltac::auto@0> $1 $2 $3