You can reverse a python list L by doing L[::-1].

So, in this case, you just create the ring with 'degneglex' and reverse the
gens list X to get Y say. Then, input the polynomials as if your variables
Y[0] to Y[n] instead of the variables X[0] upto X[n].

--Kannappan.


On Wed, Jun 18, 2014 at 3:30 AM, Stephen Kauffman <[email protected]>
wrote:

> I have some code like this:
>
>         objects = 12
>         R = BooleanPolynomialRing(objects^2,'X',order='degrevlex')
>         X = R.gens()
>
> Then
>
>         R.quotient_ring(listofpolynomials).gens()
>
> take on a particularly simple form that other term orders I've tried like
> 'lex' and 'degneglex' do not provide, however when I use 'degrevlex' as
> above I receive:
>
>         DeprecationWarning: using 'degrevlex' in Boolean polynomial rings
> is deprecated. If needed, reverse the order of variables manually and use
> 'degneglex'
>
> So how do I manually reverse the order of the auto generated generators
> X0, X1, ..., X576 as above and use 'degneglex' to achieve the same quotient
> ring generators above? I'm using X[0], X[1] to input polynomials.
>
> I assume that 'degrevlex' being deprecated for boolean polynomials has
> something to do with the fact that no indeterminate power is greater than 1
> in expanded boolean polynomials and no need to break tie like
>
>         Grevlex: x*y^2*z > x^2*z^2 > x^3 > z^2 (total degree dominates;
> lower power of z broke tie among the first two) -- from wikipedia
>
> Also I'm assuming the results of
> R.quotient_ring(listofpolynomials).groebner_basis() similarly differ
> depending on term order.
>
> Thanks
>
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