Meridional Rank of Knots Whose Exterior is a Graph Manifold
  We prove for a large class of knots that the meridional rank coincides with the bridge number. This class contains all knots whose exterior is a graph manifold. This gives a partial answer to a question of S. Cappell and J. Shaneson, see problem 1.11 on Kirby's list. 
Michel Boileau, Ederson Dutra, Yeonhee Jang, and Richard Weidmann
math.GT