#15948: DynkinDiagram with crossed nodes and labels
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Reporter: vittucek | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.2
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Vít Tuček, Travis | Reviewers:
Scrimshaw | Work issues:
Report Upstream: N/A | Commit:
Branch: | 612db215e7e89687f2dc5af38ce0915af16cc49a
public/combinat/root_systems/marked_types-15948| Stopgaps:
Dependencies: |
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Comment (by vittucek):
Replying to [comment:20 tscrim]:
> Replying to [comment:19 vittucek]:
> > Is this feature discoverable by a user? Shouldn't we add some examples
to `CartanType`'s docstring?
>
> Yes via `marked_nodes`. However we should add something to the doc of
`CartanType` (I thought I did, but I guess not).
While you are at it, there is a small typo in `type_marked.py`: substitute
`latex_relabel` by `latex_marked` in in the docstring.
>
> > You've missed the bugfix for docstring regarding our convention for
Dynkin diagrams (see commit 74c6d23eb28fd192b70e2219030d6ad60fcb9f0f).
>
> I'm not convinced yet that it is incorrect, much less that your proposal
makes anything better. I will look at it more closely and think about it
today/tomorrow (unless Dan or Nicolas, you have an opinion on this?).
Most texts on Lie algebras I've encountered define the arrows by saying
that they point from the shorter vector to the longer one (or vice versa).
Dynkin diagrams are first and foremost convenient graphical representation
(don't you agree?) and as such the "direction of the arrow" should
naturally mean the direction in the graphical representation and not the
way how we define it using Cartan matrix. I for one was quite confused by
the current docs and had to dig up Bourbaki to check it.
>
> > Would it be possible to add one more layer for weighted Cartan types?
I mean my original motivation for this patch was to be able to produce
diagrams for representation of homogeneous vector bundles which I can't
really do now. :)
> >
> > I'd add this feature myself, but I am still struggling with
understanding the current code. Is there some documentation for
programmers or design documents that would help me?
>
> IMO we should do this in a follow-up ticket as this one has a lot going
on to begin with. However it should be easy enough to do by adding a
class/file similar to `type_marked.py` and another method to the base
`CartanType_abstract` class.
OK. I would have already tried that if it weren't for build failures that
the rebasing on beta5 brought me. ;) As soon as I will get sage to build
again I'm gonna give it a shot.
--
Ticket URL: <http://trac.sagemath.org/ticket/15948#comment:21>
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