#16323: Construction of BIBD with k=5
-------------------------------------+-------------------------------------
Reporter: ncohen | Owner:
Type: enhancement | Status: positive_review
Priority: major | Milestone: sage-6.3
Component: combinatorial | Resolution:
designs | Merged in:
Keywords: | Reviewers: Vincent Delecroix
Authors: Nathann Cohen | Work issues:
Report Upstream: N/A | Commit:
Branch: | 8eac6d069e162aed9d4fc1ae3f654d0b446573da
u/vdelecroix/16323 | Stopgaps:
Dependencies: #16279 |
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Changes (by vdelecroix):
* status: needs_info => positive_review
* reviewer: => Vincent Delecroix
Comment:
Hello,
Replying to [comment:18 ncohen]:
> Hello !
>
> > Now that I read more carefully the code:
> > - why the construction using PBD can not be used from the main BIBD
function?
>
> You mean that if we had a constructor for PBD we could call it from the
BIBD constructor using BIBD_from_PBD ? It is true, but we have no PBD
constructor at the moment. Besides the two PBD constructors we already
have we could add a PBD_from_TD, stuff like that, indeed.
I bet that there are some PBD constructions in the Handbook... We should
keep in mind to reuse this code at some point.
> > In particular, considering organization, I would like to see the
functions `BIBD_from_PBD`, `_check_PBD`, `_relabel_BIBD`,
`PBD_4_5_8_9_12`, `_PBD_4_5_8_9_12_closure`, `PBD_from_TD` much higher in
the file, i.e. neither in the part "(v,4,1)-BIBD" nor in the part
"(v,5,1)-BIBD".
>
> Move stuff around if you want. As far as I am concerned, it is totally
pointless. This being said, some of those functions are together in the
code because I implemented them, following the same reference, so if you
move them apart please leave them linked together somehow.
I do not care too much. But, when I opened the file the first time it was
difficult to found the logic.
> [...]
> And if something which those constructions require is of more general
use we can of course expose it inside of the main constructor.
Indeed, this was my main question. (I had a look at various paper about
difference families, and there are a lot about k=3,4,5, very few about k=6
and almost none about k>=7; excepted existence result for very large v).
I found the work done in the branch is enough for the ticket so I set to
positive review.
Vincent
--
Ticket URL: <http://trac.sagemath.org/ticket/16323#comment:19>
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