id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
15259,"(v,4,1)-BIBD, Latin Squares and Orthogonal arrays",ncohen,,"WUUUUHUUUUUUUUUUUUUUUUUU !!
This patch implements a construction from Douglas Stinson's book ""Combinatorial Designs: Constructions and Analysis"" for (v,4,1)-BIBD, i.e. decompositions of {{{K_v}}} into copies of {{{K_4}}}. It requires the construction of some other combinatorial objects, like some Mutually Orthogonal Latin Squares and Orthogonal Arrays, an so some theorems from this book are also implemented by this patch. Hoping that the new files will get larger eventually `:-)`
I also fixed a bug in `AffineGeometryDesign` : a `List` is used instead of a `Set`, and as a result blocks are returned several times. Example :
Before
{{{
sage: print designs.AffineGeometryDesign(2, 1, GF(2)).blocks()
[[0, 1], [0, 1], [0, 2], [0, 2], [0, 3], [0, 3], [1, 2],
[1, 2], [1, 3], [1, 3], [2, 3], [2, 3]]
}}}
After
{{{
sage: print designs.AffineGeometryDesign(2, 1, GF(2)).blocks()
[[0, 1], [0, 2], [0, 3], [1, 2], [1, 3], [2, 3]]
}}}
Overall :
* A file named `bibd.py` now gathers `steiner_triple_systems` (moved there from `block_designs.py`). It also implement the present construction, and a general `BalancedIncompleteBlockDesign` is created to obtain both steiner triple systems and `(v,4,1)`-BIBD. And even some others from the online database.
* A file named `latin_squares.py` contains constructions for mutually orthogonal latin squares, as well as a function to compute the product of two latin squares.
* A file named `orthogonal_arrays.py` contains constructions for orthogonal arrays and transversal designs (which are a particular case of orthogonal arrays.
The most important thing is that **even if all the code written there is wrong** (and it is indeed very unclear at times), nothing is returned without being checked first for correctness.
Sooooooooooo well. It's rather safe `;-)`
Have fuuuuuuuuuuuuun !
Nathann",enhancement,closed,major,sage-duplicate/invalid/wontfix,combinatorics,duplicate,,dimpase vbraun wdj rbeezer,,,Nathann Cohen,N/A,,u/ncohen/15259,ffda584fb317a7d19a41046bfeaff584aa66d9c3,#15107,