[Haskell-cafe] Breaking cycles in a directed graph.

Hello. I'm currently using Data.Graph.Inductive to represent a directed graph. I want to detect all cycles within the graph and 'break' them by inserting a minimal number of nodes that are labelled with a special cycle-breaker label. Can anyone give me advice on a good algorithm for finding the cycles and finding the optimum edges to insert the cycle-breaking nodes on? Thanks Daniel