#13077: generalised Tamari lattices
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Reporter: chapoton | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: minor | Milestone: sage-5.4
Component: combinatorics | Resolution:
Keywords: poset | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Frédéric Chapoton | Merged in:
Dependencies: | Stopgaps:
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Comment (by hthomas):
Salut Frédéric--
On the contrary, I think it does make sense to have m be rational
(independent of a and b), not just integral. But, fine, that can be a
discussion for another time (or another ticket).
I think the patch should include some mathematical reference. Maybe the
paper I mentioned above by Bousquet-Mélou--Fusy--Préville-Ratelle. That
shows the m-Tamari poset is a lattice, and it's not very far from that to
the general (a,b) case, right? (Since the (a,b,m) case occurs as an
interval in the m-Tamari.) I don't think it's necessary to include a
reference for every relevant mathematical fact, of course, but I think it
could be helpful for someone who stumbles across this code to be able to
find some further information and context.
Speaking of which, I'm wondering how a user is supposed to find this code.
(I guess this is a perennial problem with Sage.) I suppose a user can
always search the manual (or the code). I wish there was some alternative
that would make it slightly easier to find things. Do you have any idea?
Is there somewhere in the posets documentation that lists implemented
posets? This seems like something which it might be worthwhile to have.
I'm a bit surprised about the way "swap" reacts if it is given a legal
string, and a position within the string, at which it is not possible to
do a swap (namely: return the same string as the answer). To me, it seems
natural to raise an error. If you like it better not to do so, though, I
think that behaviour should be documented.
cheers,
Hugh
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13077#comment:9>
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