Problems / number-theory
number-theory / Arithmetic geometry: Hodge classes, reduction and rational Tate classes
Milne's rationality conjecture for abelian varieties
Claims Theorem 1.1: for every abelian variety over Q with good reduction at a p-adic place, every residue characteristic p including 2, every rational Hodge class γ of codimension r and every divisors D1,…,Dd−r on the reduction, the ℓ-adic traces (ℓ=p) and the crystalline trace of γ0⋅D1⋯Dd−r equal one rational number. Also claims each specialized Hodge class lies in one fixed good theory of rational Tate classes, and (using the CM Hodge theorem) is represented by a rational algebraic cycle in all realizations. It does not prove the Hodge or Tate conjecture for general abelian varieties.