For $P, Q_1, \dots, Q_m \in \mathbb C[x_1, \dots, x_n]$, how to verify that $$P \in \langle Q_1, \dots, Q_m \rangle?$$
What are known algorithms to write $P$ as a combination of the $Q_1, \dots, Q_m$?
What if we replace $\mathbb C$ with another field?
My question comes from this one.
There is Buchberger's algorithm for finding a Gröbner basis.