#17798: Create a class for Coxeter matrices and types
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Reporter: tscrim | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.9
Component: group theory | Resolution:
Keywords: Coxeter groups, | Merged in:
matrices, types, days64 | Reviewers: Jean-Philippe Labbé,
Authors: Travis Scrimshaw, | Travis Scrimshaw
Jean-Philippe Labbé | Work issues:
Report Upstream: N/A | Commit:
Branch: | fe2e01fd1061c8675215050bcc120dd93dd83a5e
public/combinat/coxeter_matrices-17798| Stopgaps:
Dependencies: #17990, #18152, |
#18743 |
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Comment (by tscrim):
The fix was that the cluster seed code was assuming the indexing set of a
Cartan matrix constructed from a matrix that was of finite type had the
standard finite type indexing set of `[1, 2, ..., n]`. I fixed this by
explicitly specifying this to be the index set of the Cartan matrix.
This brings up a point that might need a discussion: Should the index set
of a matrix representing a finite type Cartan matrix be by default 1-based
or 0-based? The argument for being 1-based is above, a natural assumption
on index sets of finite type. Why we should have 0-based is consistency
with the rest for default labellings and it agrees with the indexing set
of the given matrix (and everything in python is 0-based). Thoughts?
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Ticket URL: <http://trac.sagemath.org/ticket/17798#comment:74>
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