Goal:
  
  G : t
  l : labelling
  Gl := relabel G l : t
  HGl : correct_labelling G l
  x : V.t
  p : PathOf Gl x x
  ============================
   (Z.of_nat (l x) - Z.of_nat (l x) <= 0)


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrhave@0> $1
DEBUG LTAC Evaluated term: relabel_weight
DEBUG LTAC Evaluated term: relabel_weight