This sadistic network requires that flow be pushed only on the two pipes shown in bold on the graph. An optimal solution either requires the program to learn about the topography of the network through evolution across multiple generations, or learn about the topography during runtime through message passing.
This graph shows that a solution is possible using evolutionary techniques even for the most challenging of networks. All programs managed to avoid the many pitfalls we designed into the network and send some flow from the source to the sink. The majority of programs managed to send 70% or more of the maximum capacity of 10. Two programs learned to send the maximum possible flow of 10.