Do you have the package bliss or nauty installed?
On 23/08/16 10:53, Paul Leopardi wrote:
Hi all,
I am currently trying to use Sage to classify bent functions by their
Cayley graphs.
I have attached an example where I have two (256, 120, 56, 56) strongly
regular graphs, g and h, which are also canonical labels, such that g does
not equal h, and so g and h are not isomorphic.
It takes a relatively short time to produce the canonical labels, 38.8s to
run h.is_isomorphic(g), and g.is_isomorphic(h) is still running.
The example includes the Sage code that I used to generate the graphs, as
well as a transcript of my Sage session, including the graph6_string() of
each of the two graphs.
I would like some advice on how I should proceed with the classification,
given that I want to compare about 2^(16) such graphs to a small number of
representative graphs (about 6).
I have done other tests with graphs of this size that show that usually
g.is_isomorphic(h) is faster than comparing g.automorphism_group().order()
with h.automorphism_group().order(), which is faster than comparing
g.canonical_label() with h.canonical_label().
It's just that occasionally I have found cases where g.is_isomorphic(h) is
extremely slow.
I'm thinking of using threading and a timeout of (e.g.) 5 seconds, so that
my search first tries to use g.is_isomorphic(h), and if this times out, it
then compares the automorphism group orders, and only if they are equal,
does it then compute the canonical label.
What are other people doing?
All the best, Paul
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