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Aug 23, 2016 at 17:01 comment added Steven Landsburg @DavidRoberts: They are "Lefschetz-like" conjectures, primarily this: On the cohomology of an $n$-dimensional variety $X$, let $L$ denote intersection with a hyperplane section, let $\Lambda$ be the cohomology operator defined as zero on the kernel of $L^{n-i+1}$ acting on $H^i(X)$ and as the inverse of $L$ elsewhere. Then $\Lambda$ should be induced by an algebraic cycle with rational coefficients on $X\times X $ (together with strong Lefschetz and Hodge index conjectures).
Aug 23, 2016 at 8:56 comment added David Roberts Are those conjectural properties the ones that the Standard Conjectures supply? Or ones that we know étale cohomology possesses (or perhaps crystalline)?
Aug 23, 2016 at 7:23 history edited Steven Landsburg CC BY-SA 3.0
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Aug 23, 2016 at 7:17 history answered Steven Landsburg CC BY-SA 3.0