#16846: a difference_matrices module
-------------------------------------+-------------------------------------
Reporter: ncohen | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone:
Component: combinatorial | Resolution:
designs | Merged in:
Keywords: | Reviewers:
Authors: Nathann Cohen | Work issues:
Report Upstream: N/A | Commit:
Branch: u/ncohen/16846 | 2649805f41094602cfbd2787f75028d806cf2d05
Dependencies: #16817 | Stopgaps:
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Comment (by vdelecroix):
Replying to [comment:5 ncohen]:
> Yo !
>
> > I guess that difference matrices are interesting only over Abelian
groups. Is that true?
>
> I have no idea about that, but all examples I saw were on abelian groups
indeed.
Because you can not develop a difference matrix to get an OA if the group
is non Abelian. But perhaps, difference matrices can be used for other
purposes.
> > It would be nice to coordinate with difference families for
input/output. For example, in #16802, in the database, you can ask a
difference family with a given group and not only a fixed cardinality. It
is not perfect, but I tried to start involving the group...
>
> Hmmmmm... So a structure like that ?
> {{{
> DM_constructions = {
> order_of_the_group : {
> signature_of_the_abelian_group: [
> (k1,matrix_constructor1),
> (k2,matrix_constructor2)
> ]
> }
> }
> }}}
Might be better than what I did... I used {{{ {signature: DF} }}}
> Having several difference families/matrices or OA and stuff is a hobby
of yours, you know ? To me it's just not the interesting direction `:-P`
Sometimes it is very important that your group is cyclic (for difference
families or difference matrix)... so you want to be able to ask a given
difference X over a cyclic group only.
> It can be done anyway but we have to do that later, this heap of patches
is really getting dangerous. Plus Travis wrote a patch that is totally
incompatible with this one, and there are like 10 tickets in linear order
an `needs_review` at the moment `:-P`
+1
Vincent
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Ticket URL: <http://trac.sagemath.org/ticket/16846#comment:6>
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