Goal:
  
  G1 : t
  G2 : t
  H : invariants G1
  H0 : invariants G2
  H1 : acyclic_no_loop G2
  hsub : subgraph G1 G2
  acG1 : acyclic_no_loop G1
  x : VSet.elt
  y : VSet.elt
  hx : VSet.In x (border_set G1 (EdgeSet.diff (E G2) (E G1)))
  hy : VSet.In y (border_set G1 (EdgeSet.diff (E G2) (E G1)))
  ============================
   (lsp G2 x y <= lsp G2 x y)%nbar


DEBUG:Going to execute:
fun => <coq-core.plugins.ltac::reflexivity@0>