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
  _a_ : Z
  p : SPath G1 (V G1) x y
  wp : sweight p = _a_
  ============================
   (Some _a_ <= Some (sweight (SPath_sub G2 vsub (map_spath p))))%nbar


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrapply@0> $1