If you attach a file containing
##################################################################
def PermutationGroupRing(R,G):
return PermutationGroupRing_generic(R,G)
class PermutationGroupRing_generic(CombinatorialAlgebra):
def __init__(self, R, G):
self.group = G
self._combinatorial_class = G
self._one = G.identity()
self._name = 'Group ring of %s'%str(G)
self._prefix = ''
CombinatorialAlgebra.__init__(self, R)
def _multiply_basis(self, a, b):
c = a*b
return c
def group(self):
return self.group
##################################################################
then you get the following error:
sage: F = GF(11)
sage: G = PermutationGroup([(1,2,3),(3,4,5)])
sage: attach "/home/wdj/sagefiles/codes/group_rings.sage"
sage: R = PermutationGroupRing(F,G)
sage: R.basis()
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/home/wdj/sagefiles/sage-3.0.3.rc0/<ipython console> in <module>()
/home/wdj/sagefiles/sage-3.0.3.rc0/local/lib/python2.5/site-packages/sage/combinat/combinatorial_algebra.py
in basis(self)
701
702 """
--> 703 return [self(x) for x in self._combinatorial_class]
704
705 def __call__(self, x):
/home/wdj/sagefiles/sage-3.0.3.rc0/local/lib/python2.5/site-packages/sage/combinat/combinatorial_algebra.py
in __call__(self, x)
738 return eclass(self, dict([ (e1,R(e2)) for
e1,e2 in x._monomial_coefficients.items()]))
739 #x is an element of the basis combinatorial class
--> 740 elif isinstance(x, self._combinatorial_class.object_class):
741 return eclass(self, {x:R(1)})
742 elif x in self._combinatorial_class:
TypeError: isinstance() arg 2 must be a class, type, or tuple of
classes and types
sage:
I added the method
def object_class(self):
return PermutationGroup_generic
to PermutationGroup_generic so now,
sage: R._combinatorial_class.object_class
<bound method PermutationGroup_generic.object_class of Permutation
Group with generators [(1,2,3), (3,4,5)]>
sage: R._combinatorial_class.object_class()
<class 'sage.groups.perm_gps.permgroup.PermutationGroup_generic'>
sage: isinstance(G,R._combinatorial_class.object_class())
True
It seems to me the traceback error indicates I've defined object_class
incorrectly.
Does anyone have a hint as to the right way to go here?
On Sat, Jun 28, 2008 at 12:59 PM, David Joyner <[EMAIL PROTECTED]> wrote:
> On Sat, Jun 28, 2008 at 12:48 PM, Robert Bradshaw
> <[EMAIL PROTECTED]> wrote:
>>
>> On Jun 28, 2008, at 9:33 AM, David Joyner wrote:
>>
>>> On Sat, Jun 28, 2008 at 11:00 AM, John Cremona
>>> <[EMAIL PROTECTED]> wrote:
>>>>
>>>> It seems that what Dan Bump's instructions did not specify is what
>>>> properties the class assigned to ._combinatorial_class must have.
>>>> And it needs something which PermutationGroupElement does not have.
>>>>
>>>> Does that help?
>>>
>>> Okay. Maybe the best thing is to write a wrapper to GAP's GroupRing
>>> function.
>>
>> I disagree, using CombinatorialAlgebra will be a much better option.
>>
>>>>> Can anyone explain "AttributeError: type object
>>>>> 'sage.groups.perm_gps.permgroup_element.Permutation' has no
>>>>> attribute
>>>>> 'count'"
>>>>> (in words of two syllables or less, if possible:-)?
>>
>> Sure. It means that it's trying to use a method called "count" but
>> the class "Permutation" found in sage/groups/perm_gps/
>> permgroup_element doesn't define one. What you need to do is make a
>> method called count.
>>
>> Actually, looking at the code (and someone more familiar with sage-
>> combinat should correct me) it looks like _combinatorial_class should
>> be the Parent (i.e. the group) rather than the element. It would
>> probably make sense to do something like
>>
>>> class PermutationGroupRing(CombinatorialAlgebra):
>>> def __init__(self, R, G):
>>> self.group = G
>>> self._combinatorial_class = G # NOTE the change
>>> self._one = G.identity()
>>> self._name = 'Group ring of %s'%str(G)
>>> self._prefix = ''
>>> CombinatorialAlgebra.__init__(self, R)
>>> def _multiply_basis(self, a, b):
>>> c = a*b
>>> return c
>>
>> and add a count method to the group class.
>
> That worked! Thank you!
>
>>
>> - Robert
>>
>>
>> >>
>>
>
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