Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  n : Z
  x : V.t
  y : V.t
  n0 : x = y -> False
  H : false = true
  ============================
   (x = y)


DEBUG:Going to execute:
fun flags =>
             match reverse goal with
             | |- ?X1 =>
                   <Coq.Init.Tauto.is_unit_or_eq> flags X1; constructor 1
             | H:?X1 |- _ => <Coq.Init.Tauto.is_empty> flags X1; elim H
             | _ => Ltac.assumption
             end