I'm implementing the double description algorithm in that ticket. Its of course not entirely unrelated, but doesn't do the inequality-reshuffling part for you.
On Friday, May 16, 2014 4:52:20 PM UTC+1, Dima Pasechnik wrote: > > On 2014-05-16, Jeroen Demeyer <[email protected] <javascript:>> > wrote: > > On 2014-05-15 11:33, Volker Braun wrote: > >> On Thursday, May 15, 2014 8:45:47 AM UTC+1, Jeroen Demeyer wrote: > >> > >> > IMHO, Jeroen needs to use Fourier-Motzkin elimination. > >> Yes, something like that. Elimination based purely on the H-rep > without > >> first computing the V-rep. Is this implemented in Sage? In PPL? > >> > >> > >> So is that the question, you have a problem where you can not compute > >> the V-representation of the initial set of inequalities? > > Essentially yes, although it is also a matter of patience... > > The projected polyhedron is much simpler than the original polyhedron > > before projecting. > > > >> There is no special support for doing the Fourier-Motzkin elimination > of > >> variables in Sage, but then its a pretty straightforward reshuffling of > >> the inequalities. Then one can hope to apply double description in > lower > >> dimension. > > Of course, but I personally don't feel like implementing this (I also > > don't really know about the algorithms behind this). > > Perhaps Volker's http://trac.sagemath.org/ticket/16101 > can be used as a good starting point. > I didn't read the code, but how else does he go between V and > H-representations, if not by Fourier-Motzkin... > > Dima > > -- 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/d/optout.
