Characteristic variety of a Weyl algebra module
= Characteristic variety of a Weyl algebra module
{title2=$\operatorname{Supp}(\operatorname{gr}M)$}
A good <Bernstein filtration> on a finitely generated module produces a finite graded module over $\operatorname{gr}A_n\cong\mathbb C[x_1,\ldots,x_n,\xi_1,\ldots,\xi_n]$. Its support is the characteristic variety for this filtration. Its algebraic dimension is the <Bernstein growth dimension of a Weyl algebra module>, which is independent of the choice of good filtration.