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Griffiths Groups of Supersingular Abelian Varieties
Published online by Cambridge University Press: 20 November 2018
Abstract
The Griffiths group $\text{G}{{\text{r}}^{r}}\left( X \right)$ of a smooth projective variety
$X$ over an algebraically closed field is defined to be the group of homologically trivial algebraic cycles of codimension
$r$ on
$X$ modulo the subgroup of algebraically trivial algebraic cycles. The main result of this paper is that the Griffiths group
$\text{G}{{\text{r}}^{2}}\left( {{A}_{{\bar{k}}}} \right)$ of a supersingular abelian variety
${{A}_{{\bar{k}}}}$ over the algebraic closure of a finite field of characteristic
$p$ is at most a
$p$-primary torsion group. As a corollary the same conclusion holds for supersingular Fermat threefolds. In contrast, using methods of
$\text{C}$. Schoen it is also shown that if the Tate conjecture is valid for all smooth projective surfaces and all finite extensions of the finite ground field
$k$ of characteristic
$p\,>\,2$, then the Griffiths group of any ordinary abelian threefold
${{A}_{{\bar{k}}}}$ over the algebraic closure of
$k$ is non-trivial; in fact, for all but a finite number of primes
$\ell \,\ne \,p$ it is the case that
$\text{G}{{\text{r}}^{2}}\left( {{A}_{{\bar{k}}}} \right)\,\otimes \,{{\mathbb{Z}}_{\ell }}\,\ne \,0$.
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- Research Article
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- Copyright © Canadian Mathematical Society 2002
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