Cartier isomorphism for toric varieties

Cartier modules on toric varieties

Assume that $X$ is an affine toric variety of characteristic $p > 0$. Let $Δ$ be an effective toric $Q$-divisor such that $K_X+Δ$ is $Q$-Cartier with index not divisible by $p$ and let $ϕ_Δ:F^e_* O_X \to O_X$ be the toric map corresponding to $Δ$. We identify all ideals $I$ of $O_X$ with $ϕ_Δ(F^e_* I)=I$ combinatorially and also in terms of a log resolution (giving us a version of these ideals which can be defined in characteristic zero). Moreover, given a toric ideal $\ba$, we identify all ideals $I$ fixed by the Cartier algebra generated by $ϕ_Δ$ and $\ba$; this answers a question by Manuel …

非单纯环空零点定理与堆栈GKZ理论

Nonsimplicial toric Nullstellensatz and stacky GKZ theory

引入基于Q-Cartier除子的Cox环变体，解决非单纯环空簇的缺陷，实现理想-簇对应、子概形与层的显式分类、相关环空Deligne-Mumford堆栈及GKZ/Mori理论的堆栈扩展。

Hilbert-Kunz density function and asymptotic Hilbert-Kunz multiplicity for projective toric varieties

For a toric pair $(X, D)$, where $X$ is a projective toric variety of dimension $d-1\geq 1$ and $D$ is a very ample $T$-Cartier divisor, we show that the Hilbert-Kunz density function $HKd(X, D)(λ)$ is the $d-1$ dimensional volume of ${\overline {\mathcal P}}_D \cap \{z= λ\}$, where ${\overline {\mathcal P}}_D\subset {\mathbb R}^d$ is a compact $d$-dimensional set (which is a finite union of convex polytopes). We also show that, for $k\geq 1$, the function $HKd(X, kD)$ can be replaced by another compactly supported continuous function $φ_{kD}$ which is `linear in $k$'. This gives the formula f…

On the equations and classification of toric quiver varieties

Toric quiver varieties (moduli spaces of quiver representations) are studied. Given a quiver and a weight there is an associated quasiprojective toric variety together with a canonical embedding into projective space. It is shown that for a quiver with no oriented cycles the homogeneous ideal of this embedded projective variety is generated by elements of degree at most $3$. In each fixed dimension $d$ up to isomorphism there are only finitely many $d$-dimensional toric quiver varieties. A procedure for their classification is outlined.

Non-Commutative Resolutions of Toric Varieties

Let $R$ be the coordinate ring of an affine toric variety. We show that the endomorphism ring $End_R(\mathbb A),$ where $\mathbb A$ is the (finite) direct sum of all (isomorphism classes of) conic $R$-modules, has finite global dimension. Furthermore, we show that $End_R(\mathbb A)$ is a non-commutative crepant resolution if and only if the toric variety is simplicial. For toric varieties over a perfect field $k$ of prime characteristic, we show that the ring of differential operators $D_\mathsf{k}(R)$ has finite global dimension.

具有环面作用的流形的上同调刚性：I

Cohomological rigidity of manifolds with torus actions: I

本文针对 moment-angle 流形与拓扑环面流形，证明满足组合条件的单纯球面所对应流形具有上同调刚性，并通过面环的 Tor-代数确定其组合类型。