I was wondering if the max_cardinality_matching functions is defined for directed graphs as suggested by the documentation example ? I am asking, because the linked boost reference  describes the matching only for undirected graphs.
I am trying to get the "driver nodes" of a network as described by . The authors showed, that the amount of "driver nodes needed to maintain full control of the network is determined by the ‘maximum matching’ in the network". May be even anyone has seen an implementation of this approach somewhere?
 Liu, Y.-Y., Slotine, J.-J., & Barabási, A.-L. (2011). Controllability of complex networks. Nature, 473(7346), 167–173. doi:10.1038/nature10011