[Nauty-list] digraph-->graph

[Sterten at aol.com]

you must assign (identify) a to a', else you could just permute the  's
 
 
In a message dated 19.10.2013 18:31:01 Westeuropäische Sommerzeit,  
mathieu.dutour at gmail.com writes:

One way is to duplicate the number of vertices.  
Any vertex a is associated to a pair a, a'.


A directed edge a ---> b becomes an undirected
edge {a, b'}.
We associate color 0 to all vertices x and color 1
to all vertices x'.


Mathieu



On Sat, Oct 19, 2013 at 5:53 PM, <_Sterten at aol.com_ 
(mailto:Sterten at aol.com) > wrote:


how did we best make a graph from a digraph with isomorphic  automorphism 
group  ?


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