Hilbert series of modules over Lie algebroids

Abstract

We consider modules $M$ over Lie algebroids ${\mathfrak g}_A$ which are of finite type over a local noetherian ring $A$. Using ideals $J\subset A$ such that ${\mathfrak g}_A \cdot J\subset J $ and the length $\ell_{{\mathfrak g}_A}(M/JM)< \infty$ we can define in a natural way the Hilbert series of $M$ with respect to the defining ideal $J$. This notion is in particular studied for modules over the Lie algebroid of $k$-linear derivations ${\mathfrak g}_A=T_{A/k}(I)$ that preserve an ideal $I\subset A$, for example when $A={\mathcal O}_n$, the ring of convergent power series. Hilbert series over Stanley-Reisner rings are also considered.