The rationality conjecture for locally w-Lefschetz Hodge classes

Let AA be an abelian variety over an algebraic closure of Q\mathbb{Q} with good reduction to an abelian variety A0A_{0} over an algebraic closure of a finite field. A Hodge class is locally ww-Lefschetz if its specialization lies in the adelic span of the Lefschetz classes, and it is ww-Lefschetz if its specialization is itself a Lefschetz class. Rationality conjecture. Every locally ww-Lefschetz Hodge class on AA is ww-Lefschetz. Equivalently, a Hodge class on AA fixed by the Lefschetz group L(A0)L(A_{0}) specializes to a Lefschetz class on A0A_{0}. The paper identifies this with equality of two rational structures on the relevant invariant cohomology; its resolution is not supplied here.

Sources & referencesView supporting material

Primary source

J. S. Milne, “Rational Tate classes”, arXiv:0707.3167 (2008).

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