ScalingStacks

0MYG

Proposition 3.17. Let ?∈{∗,!}?\in\{*,!\} and M∈DMG⁡(X).M\in\operatorname{DM}_{G}(X). Then MM is ??-pointwise mixed or pure Tate if and only if for each orbit 𝒪↪X\mathcal{O}\hookrightarrow X

(i,s)∗​j?​M∈DTMH⁡(k,ℚ)​ or ​(i,s)∗​j?​M∈DTMH⁡(k,ℚ)w=0​, respectively.\displaystyle(i,s)^{*}j^{?}M\in\operatorname{DTM}_{H}(k,\mathbb{Q})\text{ or }(i,s)^{*}j^{?}M\in\operatorname{DTM}_{H}(k,\mathbb{Q})^{w=0}\text{, respectively.}

Here j:G/H≅𝒪↪Xj:G/H\cong\mathcal{O}\hookrightarrow X and the functor (i,s)∗​j?(i,s)^{*}j^{?} is the composition

DMG⁡(X,ℚ)→j?DMG⁡(G/H,ℚ)→(i,s)∗DMH⁡(pt,ℚ)\operatorname{DM}_{G}(X,\mathbb{Q})\stackrel{{\scriptstyle j^{?}}}{{\to}}\operatorname{DM}_{G}(G/H,\mathbb{Q})\stackrel{{\scriptstyle(i,s)^{*}}}{{\to}}\operatorname{DM}_{H}(\operatorname{pt},\mathbb{Q})

of pullback to the orbit and the induction equivalence (3.6).

Original mathematics by the credited authors. Source collection and HTML conversion remain in progress.

Jens Niklas Eberhardt, Catharina Stroppel

Original source: arXiv:2109.00305v2