Parity conjecture for Quot schemes of points on smooth threefolds

Let r,d\begin{in}\mathbb{N}\end{in} be two positive integers and let XX be an irreducible smooth threefold. For a point [F][\mathcal F] of the Quot scheme QuotrdX\operatorname{Quot}_r^d X, write T[F]QuotrdX\mathsf T_{[\mathcal F]}\operatorname{Quot}_r^d X for its tangent space. Parity conjecture. For every [F]QuotrdX[\mathcal F]\in \operatorname{Quot}_r^d X, one has

dimCT[F]QuotrdXrd(mod2).\dim_{\mathbb{C}}\mathsf T_{[\mathcal F]}\operatorname{Quot}_r^d X\equiv r\cdot d\pmod 2.

This generalizes parity results for monomial subschemes and homogeneous finite-length modules. The conjecture has been disproved by the authors, who provide a ten-dimensional family of zero-dimensional schemes in a Hilbert scheme of points.

Sources & referencesView supporting material

Primary source

Franco Giovenzana, Luca Giovenzana, Michele Graffeo and Paolo Lella, “Unexpected but recurrent phenomena for Quot and Hilbert schemes of points”, arXiv:2403.03146 (2024).

Additional references

2 papers in this index state this conjecture (2023–2024). The statement above is taken from the most recent of them; the others are arXiv:2302.02204.

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