#10670: Mobius matrices of posets are integer matrices
------------------------------+---------------------------------------------
Reporter: chapoton | Owner:
Type: defect | Status: needs_review
Priority: minor | Milestone:
Component: combinatorics | Keywords: poset, matrix
Work_issues: | Upstream: N/A
Reviewer: Florent Hivert | Author: Frédéric Chapoton
Merged: | Dependencies:
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Changes (by newvalueoldvalue):
* owner: sage-combinat =>
* reviewer: => Florent Hivert
* author: chapoton => Frédéric Chapoton
Comment:
Hi Frédéric,
Thanks for taking care of this problem.
Here are a few remarks:
- The field Author below is used to give credits after each release. You
should put your real name here and not your login.
- If you think returning a matrix over {{{QQ}}} is a bug, then you should
make sure by a doctest that the bug is indeed fixed, indicating in
comment
the ticket number for this bug.
- I can easily imagine use cases where the Moebius function is needed
over a
different ring (eg: Z2 or a polynomial field). What about having an
optional argument {{{ring}}} with a default value {{{ZZ}}} to avoid
changing the ring twice ? In this case for consistency,
{{{.mobius_function_matrix()}}} should also take this optional
parameter too.
What do you think ?
Right now, I'm having lunch, but I'll probably find the time to post a
review
patch this evening if you don't beat me. If you start working on it please
put
a message here so that we avoid doing it twice. Of course I'll do the
same. In
any case one of us will have to do some review and the other to write some
code.
Florent
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10670#comment:6>
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