[Nauty] How to apply automorphisms?
Aisha Fenton
aishafenton at mac.com
Wed Jul 28 20:52:01 EST 2004
Hi,
I'm currently using nauty to test a pair of graphs for an isomorphism.
However, now I have a requirement that once nauty has found a canonic
labeling for two isomorphic graphs (G, H) I want to test if vertices v
in V(G) are ever mapped to y in V(H) under some automorphism.
That is, I have vertex boundary defined on each G and H. Once I have
found that G and H are isomorphic, I want to see if the boundary on G
is mappable to H (for some automorphism)
From the documentation the only way I could see was to parse the
automorphism output file, and then try each cycle - since I'm dealing
with hundreds of thousands of graphs, this method seemed like it
wouldn't be fast enough for me.
Also a newbie question. I'm not that versed in group theory, so I'd
really appreciate it if someone could give me a quick run down of how
I'm to interrupt the output automorphisms (I only need to know if
vertex x ever maps to vertex y). From my very basic group theory
knowledge, I was expecting the examples in the documentation of the
output automorphisms, to contain something like a rotation cycle
(01,2,3,4,5,6), but they don't?
Thanks heaps,
Aisha
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