#18453: Infinite affine crystals should use extended weight lattice
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Reporter: bump | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.8
Component: combinatorics | Resolution:
Keywords: crystals, days65 | Merged in:
Authors: Ben Salisbury, | Reviewers:
Anne Schilling, Travis Scrimshaw | Work issues:
Report Upstream: N/A | Commit:
Branch: | e0fd5597cb665cc8cf7d11e6d24e9e7dee691c57
public/crystal/18453 | Stopgaps:
Dependencies: |
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Comment (by aschilling):
We have the following behavior in root systems (as Travis mentioned):
{{{
sage: R = RootSystem(['B',2,1])
sage: La = R.weight_space().basis()
sage: LaE = R.weight_space(extended=True).basis()
sage: La[0] == LaE[0]
True
sage: La[0].parent() == LaE[0].parent()
False
}}}
This yields to the behavior that LS paths labeled by extended fundamental
weights and nonextended ones are considered to be the same crystal. Should
we fix the weight issue or pass another (fake) argument in the init method
to distinguish the crystals?
Nicolas, do you have an opinion on the above?
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Ticket URL: <http://trac.sagemath.org/ticket/18453#comment:29>
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