Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  y_0 : V.t
  x_0 : V.t
  Hxs : lsp G x_0 y_0 = None
  K : Z
  s0 : VSet.t
  x : V.t
  ============================
   (sweight (spath_refl G' s0 x) =
    match from_G' (spath_refl G' s0 x) with
    | inl q' => sweight q'
    | inr (q1, q2) => sweight q1 + K + sweight q2
    end)


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