Goal:
  
  G1 : t
  G2 : t
  on_edge : forall x y : V.t, EdgeOf G1 x y -> EdgeOf G2 x y
  ============================
   (forall (s : VSet.t) (x y : V.t) (p : SPath G1 s x y),
    map_spath_graph s x y p (map_spath p))


DEBUG:Going to execute:
let eos := fresh "eos" in
           pose proof CoreTactics.the_end_of_the_section as eos