Have you tried using elimination ideals? K=QQ['s,t,a0,a1,a2'] K.inject_variables() I = Ideal( a0-s^2, a1-t^2, a2 - (s^2+t^2)) I.elimination_ideal([s,t]) Ideal (a0 + a1 - a2) of Multivariate Polynomial Ring in s, t, a0, a1, a2 over Rational Field So a2 = a0 + a1 The elimination ideal tells you which algebraic relations are between s^2, t^2 and s^2+t^2. In general, you have to check if there is a polynomial in the elimination ideal that is linear in a2. I think that you can attain this taking a Grobner basis with respect to a block order where a2 > [a0,a1,x,y,z]
If you have denominators, you have to saturate the ideal with respect to them before attempting the elimination. -- 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 sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
