The Tate conjecture asserts that, for a smooth projective algebraic variety
over a finitely generated field and a prime
distinct from the field
characteristic, the classes invariant under the Galois
group in its
-adic
cohomology are generated by classes of algebraic
cycles. In codimension
, it predicts the surjectivity of the cycle-class map after
tensoring with
onto the invariant part of
.
Over a finite field, the conjecture is related to the order of the pole of the zeta
function of
at the point corresponding to codimension
. It is an arithmetic analog of the Hodge
conjecture and is known in several important special cases, but remains open
in general.
Brantner (2026) proved the integral geometric Tate conjecture for ordinary Calabi-Yau varieties of dimension three over finite
fields. Here ordinary means that its Hodge and Newton polygons agree. The result
also holds for 1-ordinary threefolds with . Here "integral" means using
the l-adic integers
as coefficients rather than
. The word "geometric" means that algebraic
cycles are taken over the algebraic closure
of the base field
. The cycle-class map must be a surjection
onto the classes in
fixed by the Galois group
for some finite extension
field
,
for every prime
distinct from the field
characteristic (Brantner 2026). It is not a proof of the general conjecture.