Published online by Cambridge University Press: 10 March 2014
Let $A/K$ be an abelian variety over a function field of characteristic
$p>0$ and let
$\ell $ be a prime number (
$\ell =p$ allowed). We prove the following: the parity of the corank
$r_\ell $ of the
$\ell $-discrete Selmer group of
$A/K$ coincides with the parity of the order at
$s=1$ of the Hasse–Weil
$L$-function of
$A/K$. We also prove the analogous parity result for pure
$\ell $-adic sheaves endowed with a nice pairing and in particular for the congruence Zeta function of a projective smooth variety over a finite field. Finally, we prove that the full Birch and Swinnerton-Dyer conjecture is equivalent to the Artin–Tate conjecture.