Tate conjecture in characteristic p for integral Shimura models

Let k(v)k(v) be the residue field at vv, let κ\kappa be a perfect field over k(v)k(v), and let xSK(κ)x\in \mathscr{S}_K(\kappa). For each prime \ell, write I,xI_{\ell,x} for the corresponding realization group, and let Autp(x)\operatorname{Aut}^p(x) denote the prime-to-pp automorphism group appearing in the realization construction. Tate conjecture in characteristic pp. There exists a reductive group IxI_x over Q\mathbb{Q} with realization maps

α ⁣:IxQQI,x\alpha_\ell\colon I_x\otimes_{\mathbb{Q}}\mathbb{Q}_\ell\to I_{\ell,x}

for all primes \ell, satisfying

Ix(Z(p))=Ix(Q)IZp,x(Zp)=Autp(x),I_x(\mathbb{Z}_{(p)})=I_x(\mathbb{Q})\cap I_{\mathbb{Z}_p,x}(\mathbb{Z}_p)=\operatorname{Aut}^p(x),

and such that the map Ix(Z(p))I,x(Q)I_x(\mathbb{Z}_{(p)})\to I_{\ell,x}(\mathbb{Q}_\ell) is the realization map from the cited quasi-isogeny construction. If κ\kappa is finite, then for every prime \ell the realization map

IxQQI,xI_x\otimes_{\mathbb{Q}}\mathbb{Q}_\ell\to I_{\ell,x}

is an isomorphism. This is the characteristic-pp analogue of the preceding Tate conjecture, combining the integral prime-to-pp realization property with the asserted isomorphism over finite fields. The source provides no evidence resolving it.

Sources & referencesView supporting material

Primary source

Keerthi Madapusi and Alex Youcis, “On canonicity for integral models of Shimura varieties with hyperspecial level”, arXiv:2604.06442 (2026).

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