#12587: simplicial complexes lack hash function
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Reporter: vpilaud | Owner: sage-combinat
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.4
Component: combinatorics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Travis Scrimshaw | Merged in:
Dependencies: | Stopgaps:
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Comment (by stumpc5):
Replying to [comment:13 tscrim]:
> Also, I found another patch by vp (which I presume is vpiluad) in the
sage-combinat queue which makes very small tweaks to `__hash__()` and
`__cmp__()` of `Simplex`. So vpiluad, would it be okay if I just delete
your patch?
My collaborator vpilaud actually opened this ticket (as his very first
ticket). You can delete his small patch in the combinat queue concerning
the hash of simplicial complexes.
We were/are working on a patch on implementing "subword complexes" (which
are simplicial complexes) as defined by Knutson and Miller in [1]. In this
context, we needed fast hashing of simplicies and of simplicial complexes
for constructing them. We now use a different algorithm, but if there will
eventually be an immutable version of simplicial complexes with fast
hashing, we might go back to another, faster algorithm.
Anyway, I appreciate your work on this!
Christian
[1] A. Knutson and E. Miller, Subword complexes in Coxeter groups, Adv.
Math. 184(1), 2004.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12587#comment:19>
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