> > I think isinteger probably makes sense for the > delsarte_bound_additive_hamming_space() function. > > Of course it does. But this function is dedicated to codes which are abelian groups, so the weight distribution coincides with the distance distribution. I didn't say that I have concerns with this function.
> The LP solver used should give exact results and not have any floating > point problems. See http://trac.sagemath.org/ticket/12533 > > As far as I know, PPL is the only exact LP solver which Sage uses. However, this backend doesn't have an IP solver. I see that the stand alone solver glpsol has the option --exact, but I do not know if this is used in IP problems. And I do not know if Sage can use this in its GLPK backend. As you apparently know more about the Sage capabilities to exactly solve IP problems, it would be nice if you share your knowledge here. > I am not sure why there would be improvements to the tables. Someone > would have noticed such improvements earlier, right? What's that supposed to mean? Here is an example: Let A(n,d) be the largest size of a binary code of length n and minimal distance >=d. The best know upper bound according to Agrell's table<http://webfiles.portal.chalmers.se/s2/research/kit/bounds/unr.html> for A(17,3) is 6552, while delsarte_bound_hamming_space(17, 3, 2 ,isinteger=True, solver="glpk") gives the *better* bound 6464! There are many more examples like this. [...] Sorry, my question was (obviously) the opposite - when does > isinteger=True give a *smaller* number compared to isinteger=False. > In many cases! If that were not the case, there would be no point offering the slow isinteger=True option at all. And indeed, for additive codes it is nice to have these stronger bounds, even if they are only correct up to numerical issues. What I tried to say in my initial message was that I believe that for non-additive codes, the option isinteger=True internally makes the mathematically unjustified assumption that the distance distribution consists of integers, or that the Delsarte inequalities do hold also for the weight distribution. So if this function uses a false assumption, this option should be removed. -- Peter Mueller > > -- You received this message because you are subscribed to the Google Groups "sage-support" 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-support. For more options, visit https://groups.google.com/groups/opt_out.
