Thank you for the answer...I have some question: -I have gf=I.groebner_fan(); where I is a 0-dimentional ideal. Now gf has the function gf.weight_vectors(); This returns the weight vectors corresponding to the reduced Groebner bases. I try to call polyedralfan() but it raises an error...maybe because I' in characteristic p prime? Anyway if i can associate the polyedralfan and i call rays I obtain the same of gf.weight_vectors()?. -now I' thinking that I'm working in finite fields...maybe I can't consider the Grobner fan...I have to study more about it....
I will post news when i'm sure of what i'm doing.... Thanks!! On Apr 1, 5:48 pm, Marshall Hampton <hampto...@gmail.com> wrote: > Unfortunately I don't think this is easy to do right now. > > If you have a Groebnerfan object for your ideal - lets call it G - > then you can get the associated polyhedral fan: > > Gp = G.polyhedralfan() > > This object has a method Gp.rays() that will give you the weight > vectors of the faces of the Groebner fan. You'd like to use those to > define a term-order; unfortunately that isn't wrapped in a real > convenient way in Sage but it is possible. If you read the help in: > > sage.rings.polynomial.term_order? > > it tells you that you can pass a term-ordering directly to Singular. > For that you need the information at: > > http://www.singular.uni-kl.de/Manual/3-1-0/sing_31.htm > > ...I think you'd want: > Wp( intvec_expression ) > > but I am not sure. > > Right now the PolyhedralFan object doesn't know which of the lower- > dimensional faces of the Groebner fan correspond to distinct bases. > That information must be available from Gfan somehow but I don't know > offhand how to extract it. > > Thanks for writing in with this question - I am more interested in > working on the interface knowing that someone is actually trying to > use it! My apologies for its limitations. > > -Marshall Hampton > > On Apr 1, 2:10 am, Andrea Gobbi <andreamat...@gmail.com> wrote:> Hi!!!!!!!!! > > How can I use > > the function grobnerfan(ideal)? > > I have to reduce a polynomial > > f(x_1,....,x_n) using all possible grobner basis in F_p. This is too > > long, and so i decided to look only the grobner fan. But I can go > > over...i have a list (of what???) given by grobnerfan, and also a list > > of weight...but i don't understand how i can reduce the polynomial. > > > I means, if i have a term order, degrvlex for exmaple, i calculate the > > grobner fan (the term order is not important). With the function > > grobnerfan i obtain a lot of possible generators of the ideal, > > depending for the term order...but if i want to reduce a polynomial > > seems that i'm using the base term order, in my case degrevlex...or > > not? > > > I hope I was clear ( I'm italian and my english is very bad!!!!)... > > Thanks!!! -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using "remove me" as the subject.
