Goal:
  
  G : t
  HI : invariants
  H : VSet.For_all (fun x : VSet.elt => lsp x x = Some 0) (V G)
  x : V.t
  p : PathOf x x
  Hp : weight p > 0
  hw : 0 < weight p + sweight (spath_refl (V G) x)
  x' : V.t
  q : SPath (V G) x' x'
  Hq : 0 < sweight q
  ============================
   (sweight q <> 0)


DEBUG:Going to execute:
intros; Zify.zify_pre_hook; zify_elim_let; zify_op