Hi Nicolas,
Thanks a lot for these hints! I need to implement a category of
multi-graded modules/algebras over a Hopf algebra (the Steenrod algebra,
specifically), so I thought subclassing AlgebrasWithBasis would be a
good idea... I've now followed your example instead, and it all seems to
work.
(I did notice that there already is a category for graded modules, but
it seems to be largely empty. I suppose that framework is still in the
making.)
Cheers,
Christian
On 05/21/2011 06:43 PM, Nicolas M. Thiery wrote:
Hi Christian,
On Fri, May 20, 2011 at 10:10:37AM +0200, Christian Nassau wrote:
I would like to create a new category that's derived from
AlgebrasWithBasis, but I get an infinite recursion when I ask for the
CartesianProducts:
Here's a simple example:
class MyAlgebrasWithBasis(AlgebrasWithBasis):
def __init__(self,R):
AlgebrasWithBasis.__init__(self,R)
Is your intention to create a subcategory of AlgebrasWithBasis? That
is a category whose objects are algebras with basis, possibly endowed
with more structure? If yes, the idiom is:
class AlgebrasWithBasis(Category_over_base_ring):
@cached_method
def super_categories(self):
return [AlgebrasWithBasis(self.base_ring())]
...
Otherwise, please describe precisely your use case to see what we
should do with it (fix the issue, raise a better warning, ...). Note
that at this point, the hierarchy of classes for categories is
basically flat:
Category
- Sets
- Semigroups
- Fields
- ...
- Category_over_base_ring
- Modules
- Algebras
- ...
Best,
Nicolas
--
Nicolas M. Thiéry "Isil"<nthi...@users.sf.net>
http://Nicolas.Thiery.name/
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