Goal:
  
  G : t
  HG : acyclic_no_loop
  x : V.t
  y : V.t
  z : V.t
  e : EdgeOf x y
  p : PathOf y z
  IHp : weight p <= sweight (simplify2 p)
  F0 : true = true -> VSet.In x (snodes (simplify2 p))
  F1 : ~ VSet.In x (snodes (simplify2 p)) <-> true = false
  q := split (simplify2 p) x (left (F0 eq_refl))
    : SPath (VSet.remove x (nodes p)) y x × SPath (nodes p) x z
  H : sweight q.1 + sweight q.2 = sweight (simplify2 p)
  ============================
   (e.π1 + weight p <= sweight q.2)


DEBUG:Going to execute:
destruct q as [q1 q2]
DEBUG LTAC Evaluated term: weight_SPath_sub
DEBUG LTAC Evaluated term: weight_SPath_sub
DEBUG LTAC Evaluated term: (weight_split (simplify2 p))
DEBUG LTAC Evaluated term: (split (simplify2 p) x (left (F0 eq_refl)))