Pink's original relative Manin–Mumford conjecture for semi-abelian schemes

Let SS be a variety over C\mathbb{C}, and let GS\mathcal{G}\to S be an algebraic family of semi-abelian varieties. Let ZGZ\subset\mathcal{G} be an irreducible closed subvariety of dimension dd that is not contained in any proper closed subgroup scheme, possibly over a smaller base, of GS\mathcal{G}\to S. Define G[>d]\mathcal{G}^{[>d]} fiberwise as the union of subgroups of codimension greater than dd.

Pink's original relative Manin–Mumford conjecture. The intersection ZG[>d]Z\cap\mathcal{G}^{[>d]} is not Zariski dense in ZZ.

The source explicitly reports a counterexample when the family has nonzero toric rank, arising from a Ribet section. Thus the original formulation is refuted.

Sources & referencesView supporting material

Primary source

Kaiyuan Gu and Chenxin Huang, “On Special Subvarieties of the Universal Semi-abelian Scheme and Pink Conjectures”, arXiv:2410.17755 (2024).

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