Goal:
  
  G1 : t
  G2 : t
  on_edge : forall x y : V.t, EdgeOf G1 x y -> EdgeOf G2 x y
  vsub : VSet.Subset (V G1) (V G2)
  weight_on_edge : forall (x y : V.t) (e : EdgeOf G1 x y),
                   (on_edge x y e).π1 >= e.π1
  x : V.t
  y : V.t
  ============================
   (forall a : Z,
    protect_term (lsp G1 x y = Some a) -> (Some a <= lsp G2 x y)%nbar)


DEBUG:Going to execute:
trivial; hnf