On Tuesday, December 24, 2013 6:22:27 AM UTC-5, Nathann Cohen wrote: > > Hellooooooo everybody !!! > > I send this email because I want to add new stuff to our combinat/designs/ > folder, and I really need some help to review patches. These are > constructions of combinatorial designs, i.e. SOoooooo very sexy set systems. > > I'm starting to get interested research-wise in this stuff. When trac was reasonably fast, I looked them over and the formatting/documentation looked fine. It seemed like Dima has looked at them as well? Now trac is so slow, and since the review system has changed from hg to git, I'd have to look up how to apply patches and test.
I have code code of my own testing+constructing weighted PDSs (essentially association schemes). It would be cool if Sage had Schur rings associated to association schemes. Every time I have to deal with them, I have to construct them by hand... > I don't think such code is available anywhere else. Those constructions > exist on paper but I don't think anybody implemented them, and it's a pity > for two reasons : > > 1) The constructions can be pretty tricky, but checking that they work on > a computer is very easy (and my code does it always, so no wrong result can > ever be returned, no fear of that) > Nice idea, Nathann! > 2) Sometimes it's even hard to just decipher the constructions from old > papers, and implementing [1] felt like saving them before it became > impossible to read it :-P > > What I try to implement these days are Balanced Incomplete Block Designs > [2], which you can see as an edge-decomposition of the complete graph K_v > into copies of K_k. > > - K_n can be decomposed into K_3 if and only if v = 1,3 [6] ( implemented > there [3], examples on [4] ) > - K_n can be decomposed into K_4 if and only if v = 1,4 [12] (several > patches waiting for a review) > - K_n can be decomposed into K_5 if and only if v = 1,5 [20] (on my hard > drive only, which can become a patch anytime) > > And then again I don't think that the decompositions are implemented > anywhere else for K_4 and K_5. > > I need help to review these patches. I understand the constructions are > very tricky, but then again *THEY ARE ALL CHECKED BEFORE SAGE RETURNS THEM* > so even if the whole construction code is gibberish there is nothing to > fear for as long as the code that checks it is correct. And this code is > dead simple. > > Sooooooo well... I need help for that, definitely. I tried to make it > *very well* documented, and if it isn't sufficient just ak me for more and > I will add them quick. > > (a shortcut, and a bugfix) > #15107 Projective Plane designs > #15285 Bug in AffineGeometryDesign > > (construction for k=4) > #15286 Latin squares > #15287 Orthogonal Arrays > #15288 Balanced Incomplete Block Designs with k=4 > > (needed for k=5) > #15310 Wilson's construction of Transversal Designs/Orthogonal Arrays/MOLS > #15431 Transversal Design TD(6,12) > > Sooo well... If you can help me with that, and of course if I can help you > with some of your patches tell me about it. > > Thaaaaaaaaaaaaaaaaaaaaaaaaank you very much !!! > > Nathann > http://www.steinertriples.fr/ncohen/ > > P.S. : please don't only answer on sage-combinat > > [1] > http://www.sagemath.org/doc/reference/combinat/sage/combinat/designs/steiner_quadruple_systems.html > [2] > http://en.wikipedia.org/wiki/Block_design#Definition_of_a_BIBD_.28or_2-design.29 > [3] > http://www.sagemath.org/doc/reference/combinat/sage/combinat/designs/block_design.html#sage.combinat.designs.block_design.steiner_triple_system > [4] http://www.steinertriples.fr/ > -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-combinat-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-combinat-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-combinat-devel. For more options, visit https://groups.google.com/groups/opt_out.
