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Lukas Prader

Publications and source records attributed to Lukas Prader.

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An arithmetic zeta function respecting multiplicities

In this paper, we study the arithmetic zeta function $$\mathscr{Z}_{\mathcal{X}}(s) = \prod_p \prod_{\substack{x \in \mathcal{X}_p \\ \text{closed}}} \Big( \frac{1}{1-|κ(x)|^{-s}} \Big)^{\mathfrak{m}_{p}(x)}$$ associated to a scheme $\mathcal{X}$ of finite type over $\mathbb{Z}$, where $κ(x)$ denotes the residue field and $\mathfrak{m}_{p}(x)$ the multiplicity of $x$ in $\mathcal{X}_p$. If $\mathcal{X}$ is defined over a finite field, then $\mathscr{Z}_{\mathcal{X}}$ appears naturally in the context of point counting with multiplicities. We prove that $\mathscr{Z}_{\mathcal{X}}$ admits a meromorphic continuation to $\{s \in \mathbb{C} \colon \mathrm{Re}(s) > \mathrm{dim}(\mathcal{X})-1/2\}$ and determine the order of its pole at $s = \mathrm{dim}(\mathcal{X})$. Finally, we relate $\mathscr{Z}_{\mathcal{X}}$ to a zeta function $ζ_f$ encoding the residual factorization patterns of a polynomial $f$.

math.NT

A local-global principle for surjective polynomial maps

Let $R$ be an affine domain of characteristic zero with finite quotients. We prove that a polynomial map over $R$ is surjective if and only if it is surjective over $\hat{R_{\mathfrak{m}}}$, the completion of $R$ with respect to $\mathfrak{m}$, for every maximal ideal $\mathfrak{m} \subseteq R$. In fact, the completions $\hat{R_{\mathfrak{m}}}$ may be replaced by arbitrary subrings containing $R$. We use this result to yield a characterization of surjective polynomial maps, and remark that there does not exist a similar principle for injective polynomial maps.

math.AC