Abstract
We introduce Kummer surfaces \(X={\text {Km}}(C\times C)\) with the group scheme \(G=\mu _2\) acting on the self-product of the rational cuspidal curve in characteristic two. The resulting quotients are normal surfaces having a configuration of sixteen rational double points of type \(A_1\), together with a rational double point of type \(D_4\). We show that our Kummer surfaces are precisely the supersingular K3 surfaces with Artin invariant \(\sigma \le 3\), and characterize them by the existence of a certain configuration of thirty curves. After contracting suitable curves, they also appear as normal K3-like coverings for simply-connected Enriques surfaces.
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Acknowledgements
We wish to thank the referee for valuable comments and pointing out inaccuracies. The research of the first author is partially supported by Grant-in-Aid for Scientific Research (S) No. 15H05738. The research of the second author is conducted in the framework of the research training group GRK 2240: Algebro-geometric Methods in Algebra, Arithmetic and Topology, which is funded by the DFG.
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Kondō, S., Schröer, S. Kummer surfaces associated with group schemes. manuscripta math. 166, 323–342 (2021). https://doi.org/10.1007/s00229-020-01257-4
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DOI: https://doi.org/10.1007/s00229-020-01257-4