[Boost-users] how to schedule nodes in graph

Hi, I want to do the following: I have a graph in boost. Now I want to schedule the graph nodes in topological order as follows: 1. The nodes which do not have any parents are to be scheduled in first cycle. Record the list of these nodes. 2. Remove already recorded nodes (in step 1) from the graph. 3. Repeat 1 and 2 on the remaining graph and so on. How to do the above? I need functions: 1. Get all nodes which do not have parents. 2. To remove the nodes from graph. Please suggest me about the functions in boost so do the same. Thanks, Suresh