#16281: redesign projective plane
-------------------------------------+-------------------------------------
Reporter: vdelecroix | Owner:
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-6.2
Component: combinatorics | Resolution:
Keywords: design, | Merged in:
projective plane | Reviewers:
Authors: Vincent Delecroix | Work issues:
Report Upstream: N/A | Commit:
Branch: | 429d815568a0e4a90e4968e55d45548f2e0c7262
u/vdelecroix/16281 | Stopgaps:
Dependencies: |
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Changes (by ncohen):
* status: needs_review => needs_info
Comment:
Heeeeeeeeereis the review !
- Designs end with "Design", i.e. !DesarguesianProjectivePlaneDesign. I
don't say that it is a good idea, but that we should change it for all of
them or not at all. Plus Dima will complain.
- Why not use deprecated_function_alias for designs.!ProjectivePlaneDesign
?
- You can do this instead
{{{
relabel = {x:i for i,x in enumerate(K)}
Klist = relabel # Klist represent the set of elements of K
}}}
- `projective_plane_to_OA`: there is a function in bibd.py called
`_relabel_BIBD` that takes a BIBD on n points as input (here it would be a
projective plane) and relabels its elements in such a way that
[[0,..,k-2,n],[k-1,...,2*k-2,n],...,[n-k-1,n-1]] are sets of the BIBD. So
well. It actually does what you are doing : it relabels the BIBD such that
when you remove all blocks containing n-1 you get a well-labelled TD.
- `OA_to_projective_plane` I implemented something VERY SIMILAR in #16279
but not equivalent :-)
- `OA_to_projective_plane` : Why do you need to relabel anything ?
{{{
+ # add the n^2 lines that correspond to transversals
+ for l in OA:
+ blcks.append([i+(n+1)*j for i,j in enumerate(l)])
}}}
The OA is already well labelled. The BIBD is exactly the blocks from the
OA plus the k groups union the new element, isn't it ? This should just be
a deepcopy.
- Isn't the triangle a Projective Plane of order 1 ?
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/16281#comment:3>
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