Étale 1-motive realization conjecture in positive characteristic

Fix a perfect field kk of characteristic p0p\geq 0, and let Sch/kSch/k denote the category of separated finite type kk-schemes. Let M1(k)\mathscr{M}^1(k) be the category of free 1-motives over kk, and let TT_\ell be their \ell-adic realizations for primes p\ell\ne p. For the full subcategory Schd/kSch/kSch_d/k\subset Sch/k of dd-dimensional separated finite type kk-schemes, the conjecture concerns functors

M1(),Mc1():(Sch/k)opM1(k)M^1(-),M_c^1(-):(Sch/k)^{op}\longrightarrow\mathscr{M}^1(k)

and

M2d1(),Mc2d1():(Schd/k)opM1(k).M^{2d-1}(-),M_c^{2d-1}(-):(Sch_d/k)^{op}\longrightarrow\mathscr{M}^1(k).

Étale 1-motive realization conjecture. These functors should satisfy, functorially in XX, for every prime p\ell\ne p,

TM1(X)H1(Xk,Z(1)),TMc1(X)Hc1(Xk,Z(1)),T_\ell M^1(X)\cong H^1(X_{\overline{k}},\mathbb{Z}_\ell(1)),\qquad T_\ell M_c^1(X)\cong H_c^1(X_{\overline{k}},\mathbb{Z}_\ell(1)),

and, for XSchd/kX\in Sch_d/k,

TM2d1(X)H2d1(Xk,Z(d))/torsion,T_\ell M^{2d-1}(X)\cong H^{2d-1}(X_{\overline{k}},\mathbb{Z}_\ell(d))/\mathrm{torsion}, TMc2d1(X)Hc2d1(Xk,Z(d))/torsion.T_\ell M_c^{2d-1}(X)\cong H_c^{2d-1}(X_{\overline{k}},\mathbb{Z}_\ell(d))/\mathrm{torsion}.

This is an \ell-adic analogue of the stated special case of Deligne's conjectures on 1-motives. The source restricts to perfect fields because it says that the conjecture is not clearly expected to hold over non-perfect fields; its resolution status is not specified.

Sources & referencesView supporting material

Primary source

Peter Mannisto, “Albanese and Picard 1-Motives in Positive Characteristic”, arXiv:1308.0472 (2013).

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