 However, given an n-vertex weighted planar graph, the best upper bound  is only O(\log n)  by Rao [SoCG99].
<fluency>  However, given an n-vertex weighted planar graph, the best upper bound  is only O(\log n)  by Rao [SoCG99].
 However, given an n-vertex weighted planar graph, the best upper bound is only O(\log n) , by Rao [SoCG99].