Goal:
  
  G : t
  invG : invariants G
  acG : acyclic_no_sloop G
  x : V.t
  p : PathOf G x x
  wp : weight p > 0
  rx := spath_refl G VSet.empty x : SPath G VSet.empty x x
  hsupp : VSet.Equal (VSet.union VSet.empty (nodes G p)) (nodes G p)
  s0 := simplify G p rx hsupp : ∑ x' : V.t, SPath G (nodes G p) x' x'
  weight_simplify0 : 0 < weight p + 0 ->
                     0 < sweight (simplify G p rx hsupp).π2
  ============================
   (sweight (simplify G p rx hsupp).π2 > 0)


DEBUG:Going to execute:
zify_op