#20402: Make subword complexes compatible with real reflection groups
-------------------------------------+-------------------------------------
Reporter: stumpc5 | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-7.2
Component: combinatorics | Resolution:
Keywords: reflection group, | Merged in:
coxeter group, subword complex, | Reviewers:
days80 | Work issues:
Authors: Christian Stump | Commit:
Report Upstream: N/A | 0ee1f3bf9c772352b9a7994afc7f4359e618b309
Branch: u/stumpc5/20402 | Stopgaps:
Dependencies: #11187 |
-------------------------------------+-------------------------------------
Changes (by tscrim):
* status: needs_review => needs_work
Comment:
-1 to changing all of the examples to ''only'' using GAP3/reflection
groups. Until GAP3 becomes an optional spkg, it means they become
completely untested. Moreover, it is good to make sure the functionality
works between different implementations.
I think there are a few things in here which need to be abstracted up to
the category, root system code, and/or Coxeter type code. For example,
`is_crystallographic` should be called on the Coxeter type, of which
`ReflectionGroup` does not have and should (or perhaps the Coxeter
matrix).
I also do not see the reason why this change is needed:
{{{#!diff
- Lambda = {li: coeff[li] * Lambda[li] for li in Lambda}
+ Lambda = {li: coeff[li] * Lambda[li] for li in
Lambda.keys()}
}}}
as the iteration for a dictionary is over its keys (and the former is
faster and more memory efficient). With this change:
{{{#!diff
- V_weights.append(pi * fund_weight)
+ # TODO: little hack to distinguish the implementations
+ # for ReflectionGroups and CoxeterGroup
+ from sage.groups.perm_gps.permgroup_element import
PermutationGroupElemen
+ if isinstance(pi,PermutationGroupElement):
+ V_weights.append( sum(fund_weight[j]*Phi[
(~pi)(j+1)-1 ] for j in ran
+ else:
+ V_weights.append(pi * fund_weight)
}}}
I think it would be better to have the fundamental weights handle the
action of the reflection group element.
--
Ticket URL: <http://trac.sagemath.org/ticket/20402#comment:17>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at https://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
