Goal:
  
  G1 : t
  G2 : t
  on_edge : forall x y : V.t, EdgeOf G1 x y -> EdgeOf G2 x y
  weight_on_edge : forall (x y : V.t) (e : EdgeOf G1 x y),
                   (on_edge x y e).π1 <= e.π1
  s : VSet.t
  x : V.t
  y : V.t
  p : SPath G1 s x y
  ============================
   (forall (s : VSet.t) (x y : V.t) (s1 : VSet.t) (y' : V.t),
    DisjointAdd x s1 s ->
    forall (e : EdgeOf G1 x y') (p : SPath G1 s1 y' y),
    sweight (map_spath p) <= sweight p ->
    (on_edge x y' e).π1 + sweight (map_spath p) <= e.π1 + sweight p)


DEBUG:Going to execute:
move  =>? ? ? ? ? ? e ?; move : (weight_on_edge _ _ e) 
Level 0: Backtrace:

No matching clauses for match.
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.
Level 1: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.