On 4 Jan 2014 20:11, "David Joyner" <[email protected]> wrote: > > > > 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?
I did, briefly. I will have some time for this in the 2nd half of January, after we are back to Oxford. > 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-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/groups/opt_out.
