#17216: Poset / LatticePoset: [meet|join]matrix algorithm
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Reporter: jmantysalo | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jori Mäntysalo | Reviewers: Nathann Cohen
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/poset___latticeposet___meet_join_matrix_algorithm|
a649be931b249028ff1e5961fc948c2daf50c695
Dependencies: | Stopgaps:
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Comment (by ncohen):
Yo !
> 1) Should empty set be a lattice? Anyways, this is now corrected. Should
have a test suite containing tests for empty semilattices too. Actually a
test suite should test all properties for 0- and 1-element posets. (How
about `is_chain()`, for example?)
Well. I just asked a friend, and as usual it depends on the definition
that you prefer. He told me that a lattice should have a maximum and
minimum element. The definition I prefer is that "any two guys have both a
meet and a join", which hold for an empty set. I do not mind much to be
honest, I always suspect other to use different conventions than I, so I
usually do not trust softwares for that `:-P`
> 2) Hmm... I think I'll think about this on next round iterating throught
the code.
Oh, I had not seen that the code was already like that before you modified
it. Well, looks good to go !
Nathann
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Ticket URL: <http://trac.sagemath.org/ticket/17216#comment:9>
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