Finding a Minimum Equivalent Graph of a Digraph

I'm looking for an implementation preferably in Java of an algorithm for finding a Minimum Equivalent Graph of a Digraph (htt开发者_StackOverflow社区p://portal.acm.org/citation.cfm?id=321526.321534).

Even better would be an implementation of "Approximating the minimum equivalent digraph" http://cat.inist.fr/?aModele=afficheN&cpsidt=3634076 (requires ACM membership, sorry) alternative link http://www.cs.umd.edu/~samir/grant/kry94b.ps (postscript)

Have you tried taking a look at java graph algorithms libraries, like JGraphIT ?