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arXiv · 2510.27031

Free curves and fundamental groups

Eric Jovinelly·Brian Lehmann·Eric Riedl
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Abstract

We show that klt Fano varieties and certain lc Fano varieties contain free higher-genus curves in their smooth loci. Our methods also allow us to find free curves on varieties in positive characteristic and on quasiprojective varieties, under a natural positivity condition on the tangent bundle. We then use the existence of free curves to deduce finiteness of the fundamental group of the smooth locus in these settings. The paper includes an appendix by de Jong that establishes the K\"unneth formula for tame \'etale fundamental groups.

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Eric Jovinelly, Brian Lehmann, Eric Riedl. 2025-10-30. Free curves and fundamental groups. https://arxiv.org/abs/2510.27031

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