Goal:
  
  x : V.t
  n : Z
  y : V.t
  H : V.lt x x \/ V.eq x x /\ n < n \/ V.eq x x /\ n = n /\ V.lt y y
  ============================
   False


DEBUG:Going to execute:
match goal with
           | |- ?X1 -> ?X2 => intro
           | |- ~ _ => unfold not at 1; intro
           end