[Nauty] Searching for automorphisms of only one colour

[Brendan McKay]

* Christopher Jefferson <caj at cs.york.ac.uk> [021015 00:23]:
> 
> My "problem" is that I have a coloured graph where the first "colour" 
> represents variables and the other coloured nodes represent various 
> relations. Stabilizing these other groups is quite easy, as the generators 
> for them are separate, so I just cut them out of the answer. While this 
> works quite well, I expect that if there as some way I could search for 
> only the automorphisms of one colour, things would go even faster!
> 
> Is there a way to do this, or simple alteration I could make to nauty to do 
> this?

Without knowing the graph structure I can't be sure I'm answering
the right question.  Is this the problem:
   There may be symmetries amongst the relations even when the
   variables are all fixed, and you don't want such symmetries
   to appear in the nauty output. ??
Is it true by any chance that the relation vertices are only
joined to variable vertices?  And vice-versa?

I'll say more when you reply to the above.  Or at least when
I wake up (now it is 00:50am here).

Brendan.