Hi,
This weekend I was introducing Sage to a friend. To illustrate Jmol, I
showed him some 3d Cayley graphs of some finite groups :
{{{
sage: S = SymmetricGroup(4)
sage: S.cayley_graph()
Digraph on 24 vertices
}}}
Then, he asked me to show the Cayley graph of some groups he often
works with :
{{{
sage: g = GL(2,GF(3)); g
General Linear Group of degree 2 over Finite Field of size 3
sage: g.order()
48
sage: g.cayley_graph()
Traceback (most recent call last):
...
AttributeError: 'GeneralLinearGroup_finite_field' object has no
attribute 'cayley_graph'
}}}
{{{
sage: G = WeylGroup(['D',4])
sage: G
Weyl Group of type ['D', 4] (as a matrix group acting on the ambient
space)
sage: G.order()
192
sage: G.cayley_graph()
Traceback (most recent call last):
...
AttributeError: 'WeylGroup_gens' object has no attribute
'cayley_graph'
}}}
The reason is that cayley_graph is implemented in the class
sage.groups.group.FiniteGroup but both WeylGroup_gens and
MatrixGroup_gap_finite_field inherits only from
sage.groups.group.Group.
I already begun a patch available in the sage-combinat tree. Mainly,
the changes are :
-class MatrixGroup_gap_finite_field(MatrixGroup_gap):
+class MatrixGroup_gap_finite_field(MatrixGroup_gap, FiniteGroup):
-class WeylGroup_gens(ClearCacheOnPickle, UniqueRepresentation,
MatrixGroup_gens):
+class WeylGroup_gens(ClearCacheOnPickle, UniqueRepresentation,
MatrixGroup_gens, FiniteGroup):
My question is the following : Am I right to assume that both
WeylGroup_gens and MatrixGroup_gap_finite_field are always finite?
Thank you,
Sébastien Labbé
Laboratoire de Combinatoire Informatique Mathématique (LaCIM)
UQAM, Montréal
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