What is the name of the following theorem / result ?
There exist $x_1, x_2 ... x_n$ in $\mathbb{C}$ such that $f_i(x_1, x_2 ... x_n) = 0$ for each $i$ between $1$ and $k$ (i.e the variety is not null) if and only if the Groebner base of the ideal generated by $f_1$, ... $f_k$ is not $\{1\}$.