Topological complexity of collision free motion planning algorithms in   the presence of multiple moving obstacles
  We study motion planning algorithms for collision free control of multiple objects in the presence of moving obstacles. We compute the topological complexity of algorithms solving this problem. We apply topological tools and use information about cohomology algebras of configuration spaces. The results of the paper may potentially be used in systems of automatic traffic control. 
Michael Farber, Mark Grant and Sergey Yuzvinsky