Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  n : Z
  x : V.t
  y : V.t
  l : (Some n <= lsp G x y)%nbar
  H : (Some n <= lsp G x y)%nbar
  ============================
   (is_true true)


DEBUG:Going to execute:
fun id0 id1 X2 => assert X2; [ exact (id0 id1) | clear id0 ]