Abstract
We study dominant rational maps from a product of two curves to surfaces with \(p_{g} = q = 0\). Given two curves which satisfy a mild genericity assumption and have large genus relative to their gonality, we show that the degree of irrationality of their product is equal to the product of their gonalities. Moreover, we prove that the degree of irrationality of a product of two hyperelliptic curves is 4.
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Notes
By hyperelliptic curve, we mean a curve of genus at least 2 with a \(g^{1}_{2}\).
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Acknowledgements
We would like to thank Rob Lazarsfeld for valuable discussions and for suggesting that one could trace 2-forms to study low degree rational maps. We would also like to thank Mihnea Popa and Geoffrey Smith for helpful comments.
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Nathan Chen’s research was partially supported by an NSF postdoctoral fellowship, DMS-2103099.
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Chen, N., Martin, O. Rational maps from products of curves to surfaces with \(p_g = q = 0\). Math. Z. 304, 62 (2023). https://doi.org/10.1007/s00209-023-03312-8
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DOI: https://doi.org/10.1007/s00209-023-03312-8