Goal:
  
  G : t
  l : labelling
  Gl := relabel G l : t
  HGl : correct_labelling G l
  x : V.t
  p : PathOf Gl x x
  acG : acyclic_no_loop G
  xx0 : lsp G x x = Some 0
  ============================
   (Z.of_nat (l x) - Z.of_nat (l x) <= 0)


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrmove@1> $1 $2