Goal:
  
  n1 : Z
  y1 : V.t
  y2 : V.t
  x3 : V.t
  n3 : Z
  y3 : V.t
  H1' : n1 < n3
  H2'' : V.lt y2 y3
  T1 : V.lt x3 x3 -> V.lt x3 x3 -> V.lt x3 x3
  T2 : V.lt y1 y2 -> V.lt y2 y3 -> V.lt y1 y3
  T3 : n1 = n3 -> n3 = n3 -> n1 = n3
  ============================
   ((n3 = n3 -> n1 = n3) ->
    x3 = x3 /\ n1 < n3 \/ x3 = x3 /\ n1 = n3 /\ V.lt y1 y3)


DEBUG:Going to execute:
<coq-core.plugins.ltac::intro@0>