Changes between Version 9 and Version 10 of Ticket #27571


Ignore:
Timestamp:
04/20/19 13:34:18 (8 months ago)
Author:
dcoudert
Comment:

I tried to investigate further on the possible cause of the issues with automorphism_group and the Python3 failing doctests in src/sage/graphs/generators/families.py.

The good news is that we have the same result with 'bliss' and 'sage'

sage: G = graphs.PaleyGraph(9)
sage: a = G.automorphism_group(partition=[sorted(G)])
sage: it = (x for x in a.normal_subgroups() if x.order() == 9)
sage: subg = next(iter(it))
sage: r = [matrix(libgap.PermutationMat(libgap(z), 9).sage())
....:      for z in subg]
sage: ff = list(map(lambda y: (y[0]-1,y[1]-1),
....:          Permutation(map(lambda x: 1+r.index(x^-1), r)).cycle_tuples()[1:]))
sage: L = sum(i*(r[a]-r[b]) for i,(a,b) in zip(range(1,len(ff)+1), ff)); L
[ 0  1 -1 -3 -2 -4  3  4  2]
[-1  0  1 -4 -3 -2  2  3  4]
[ 1 -1  0 -2 -4 -3  4  2  3]
[ 3  4  2  0  1 -1 -3 -2 -4]
[ 2  3  4 -1  0  1 -4 -3 -2]
[ 4  2  3  1 -1  0 -2 -4 -3]
[-3 -2 -4  3  4  2  0  1 -1]
[-4 -3 -2  2  3  4 -1  0  1]
[-2 -4 -3  4  2  3  1 -1  0]

sage: G.relabel()
sage: G3x3=graphs.MathonPseudocyclicStronglyRegularGraph(2,G=G,L=L)
sage: G3x3.is_strongly_regular(parameters=True)
(441, 220, 109, 110)
sage: G3x3.automorphism_group(algorithm="bliss").order() # optional - bliss
3  # <-- expect 27 in Python 2 
sage: G3x3.automorphism_group(algorithm="sage").order() # long time
3  # <-- expect 27 in Python 2 

The issue may come from PermutationGroup that is used in both case...

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  • Ticket #27571 – Description

    v9 v10  
    4545
    4646
    47 Other doctests are still failing with py3 and bliss.
     47Other doctests are still failing with py3 and bliss and could be fixed in another ticket.