Suppose we have a polynomial $P$ and a set of polynomials $Q_1,...,Q_n$, and it is possible to calculate the Groebner basis $G$ of the ideal generated by all the $Q_i$. Let $R$ be the remainder of $P$ after reducing by $G$. In Sage, how can we find polynomials $S_1,...,S_n$ such that $P = R + \sum S_i Q_i$?