[Nauty-list] directed bipartite graphs using genbg and directg

[Brendan McKay]

Excellent question!  I can add this facility in a few minutes (but
give me a day).  I will insert a switch that is already in multig:
   -f#  Use the group that fixes the first # vertices setwise

You would give it the number of vertices in the first part, such as
-f2 in your example, then it will not try to mix up the first part
of the graph with the rest. I don't foresee a problem.

Brendan.

* Anastasia <cryptovolans at gmail.com> [070712 10:26]:
> Hello All,
> I have a limited understanding of graph theory, so I appreciate your
> patience and any advice or corrections.
> 
> I am attempting to generate nonisomorphic, unlabeled, directed, bipartite
> graphs. Both genbg and directg are working well, but I need a few more
> graphs than directg returns. 
> 
> For example, I used ./genbg -c -d2:1 -D4:100 2 2 1:100 | ./directg -T, so
> there are 2 vertices in the first set (0 and 1) and 2 vertices in the second
> set (2 and 3).
> One of the graphs output by directg is:
> 0 2 2 0 0 3 3 0 1 2 2 1 1 3
> but it doesn't output this graph:
> 0 2 2 0 0 3 3 0 1 2 2 1 3 1
> 
> I think these graphs are nonisomorphic if they are considered as bipartite
> (so I need both graphs), but are isomorphic if they are not considered as
> bipartite (so the second graph is omitted by directg). Is it possible to get
> these directed bipartite graphs with options/modifications in directg?
> 
> Thank you for your time,
> Anastasia
> 
> 
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