#6588: Categories for root systems
--------------------------------------------------------+-------------------
Reporter: nthiery | Owner:
mhansen
Type: enhancement | Status:
needs_review
Priority: major | Milestone:
sage-5.0
Component: combinatorics | Keywords: root
systems, categories
Work_issues: | Upstream: N/A
Reviewer: Anne Schilling, Mark Shimozono, PatchBot | Author:
Nicolas M. Thiéry
Merged: | Dependencies:
#10817
--------------------------------------------------------+-------------------
Comment(by aschilling):
Replying to [comment:17 nthiery]:
> Replying to [comment:16 aschilling]:
> > You are welcome. I hope you will return the favor for trac_12536
-linear_extensions-as.patch!
>
> I sure will, soon!
Thanks.
> > > Crystals are only implemented in sage.combinat.crystals (so far).
But
> > > this names an area of mathematics. So this fits a bit more the first
> > > case.
> >
> > No, there is a lot of crystal code in /sage/categories: crystals,
finite_crystals, highest_weight_crystals, ....
>
> I meant: the crystals themselves (CrystalOfLetter, KR, ...) are all in
> implemented in sage.combinat.crystals.
But these are not categories, they are classes. In your case, a cateogory
is in
/sage/combinat/root_systems/
> > Why can't fundamental_weights when "extended" is set also include
> > `delta`? This would at least fit with the notational abuse of
> > fundamental_weight.
>
> Because we want to do things like:
>
> sage: x in self.fundamental_weights()
>
> sage: all(L.some_property() for L in self.fundamental_weights())
>
> So adding delta would change the semantic of fundamental_weights.
> Whereas the current abuse of fundamental_weight can't break any code.
How about self.fundamental_weights(extended = True) with default extended
= False?
> > I also wrote another very small reviewer's patch that you can fold in.
>
> I don't see it on the queue; did you push?
Sorry, I forgot to push. It should be there now.
Best,
Anne
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6588#comment:18>
Sage <http://www.sagemath.org>
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