The Bloch–Lewis conjecture on algebraically trivial codimension-two cycles

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Let XX be a smooth variety. Write CH2(X)algCH^2(X)_{\emph{alg}} for the group of algebraically trivial codimension-two cycles, and let Ja2(X)J_a^2(X) be the abelian variety given by the image of the restriction of the Abel–Jacobi map to CH2(X)algCH^2(X)_{\emph{alg}}. Assume

H2,0(X)=0,H^{2,0}(X)=0,

and assume that the generalized Hodge conjecture holds for XX.

Bloch–Lewis conjecture. Then CH2(X)algCH^2(X)_{\emph{alg}} is finite-dimensional, and consequently

CH2(X)alg≅Ja2(X).CH^2(X)_{\emph{alg}}\cong J_a^2(X).

Here finite-dimensionality means that a smooth curve and a correspondence from it induce a surjection onto CH2(X)algCH^2(X)_{\emph{alg}}. The claim connects the generalized Hodge conjecture with the structure of algebraically trivial codimension-two cycles and their Abel–Jacobi images. The source gives no resolution status for this implication.

References

Primary source

Benjamin Diamond, “Smooth Surfaces in Smooth Fourfolds with Vanishing First Chern Class”, arXiv:1610.04266 (2018).

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