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
  ============================
   (VSet.Equal (VSet.union VSet.empty (nodes G p)) (nodes G p))


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrapply@0> $1
DEBUG LTAC Evaluated term: (VSet.Equal (VSet.union VSet.empty (nodes G p))
                              (nodes G p)
                            :
                            Type)