Hi,

I'm trying to port a Mathematica project to sympy. Therefore, I would
like to use an algorithm to decompose an expression using Gröbner
Bases as described in

8.3 Algebraic Relations, Gröbner Bases: A Short Introduction for
Systems Theorists ( http://people.reed.edu/~davidp/pcmi/buchberger.pdf
)

I already figured out, that sympy offers a function to compute Gröbner
Bases.
However, what could a solution, similar to what Mathematica's
PolynomialReduce does in this case, look like in sympy?
Alternatively, I could for now solve my problem with simple variables
instead of polynomials and use something similar to Mathematica's
Coefficient[] to pull out the according coefficients from the
expression.


This is my Mathematica code for the example:
---------------------------------------------------------------------------
pv = {x1^2 + x2^2,  x]^2*x2^2,  x1^3*x2 - x1*x2^3}
tau1 =  x1^7*x2 - x1*x2^7
Vars = {x1, x2, Subscript[j, 3], Subscript[j, 2], Subscript[j, 1]};
Table[-Subscript[j, i] + pv[[i]], {i, Length[pv]}]
G = FullSimplify[
       GroebnerBasis[
            Table[-Subscript[j, i] + pv[[i]], {i, Length[pv]}], Vars]
       ];

MatrixForm[G]

{Cf, mRest} = PolynomialReduce[tau1, G, Vars];
Cf
mRest
--------------------------------------------------------------------------

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