Hey Andrew,
It may not be the best name, but if you pass
implementation="permutation", then it will go to the chevie implementation.
This isn't explicitly mentioned in the doc (and probably should be), but
the doctests testing this are marked as optional needing chevie. So I think
what you need is already there.
Best,
Travis
On Sunday, November 9, 2014 9:11:48 PM UTC-8, Andrew wrote:
>
> Hi Travis,
>
> Thanks for the ultra quick reply. I'm impressed that so much work being
> done on this as I assumed that it was all in the too hard basket. I'll have
> a quick look at calls and see how hard it is to wrap something around
> chevie's implementation.
>
> Andrew
>
> On Monday, 10 November 2014 15:43:30 UTC+11, Travis Scrimshaw wrote:
>>
>> Hey Andrew,
>>
>> Am I right in thinking that sage does not (yet) know about the left,
>>> right and two-sided Kazhdan-Lusztig cells of Coxeter groups? As sage can
>>> compute Kazhdan-Lusztig polynomials I assumed that it knew about cells as
>>> well, but it doesn't seem to. Please tell me if I am missing something.
>>>
>>
>> AFAIK, there's no code in Sage or ticket about cells. +1 to adding them.
>>
>>>
>>> Incidentally, I also noticed that we have some identity issues -- that I
>>> am sure are well known:
>>>
>>> sage: WeylGroup("A5")
>>> Weyl Group of type ['A', 5] (as a matrix group acting on the ambient
>>> space)
>>> sage: CoxeterGroup("A5")
>>> Coxeter group over Universal Cyclotomic Field with Coxeter matrix:
>>> [1 3 2 2 2]
>>> [3 1 3 2 2]
>>> [2 3 1 3 2]
>>> [2 2 3 1 3]
>>> [2 2 2 3 1]
>>>
>>> I am guessing that one of these is just wrapping code from chevie, but I
>>> haven't checked. Is there any reason not to amalgamate these two classes?
>>> Currently the CoxeterGroup code seems marginally faster but perhaps the
>>> WeylGroup classes have more functionality:
>>>
>>
>> I implemented the current CoxeterGroup and it uses Sage's (hence
>> gap's) matrix group code. However the WeylGroup does have more information
>> (features) since it is considered acting on the root/weight lattice, such
>> as reflection_to_root on elements. Combining these classes might be taken
>> care of by http://trac.sagemath.org/ticket/15703.
>>
>>>
>>> sage: WeylGroup("A5").cardinality()
>>> 720
>>> sage: CoxeterGroup("A5").cardinality()
>>>
>>> ---------------------------------------------------------------------------
>>> NotImplementedError Traceback (most recent call
>>> last)
>>> <ipython-input-6-42496321af01> in <module>()
>>> ----> 1 CoxeterGroup("A5").cardinality()
>>>
>>> /usr/local/src/sage/local/lib/python2.7/site-packages/sage/categories/
>>> sets_cat.pyc in cardinality(self)
>>> 1370 NotImplementedError: unknown cardinality
>>> 1371 """
>>> -> 1372 raise NotImplementedError("unknown cardinality")
>>> 1373
>>> 1374 # Functorial constructions
>>>
>>> NotImplementedError: unknown cardinality
>>>
>>> There's currently http://trac.sagemath.org/ticket/16630 which should
>> fix some (all?) of these issues (and I will get to that after next week).
>>
>> Best,
>> Travis
>>
>>
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