Abstract
We construct a large class of projective threefolds with one node (aka non-degenerate quadratic singularity) such that their small resolutions are not projective.
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Acknowledgements
The author is grateful to Ivan Cheltsov and Constantin Shramov for useful discussions, and to Alexander Braverman for communicating Lemma 2.5 with an idea of its proof. It is a pleasure to thank the anonymous referees for numerous helpful suggestions, which contributed much to improvement of the text.
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Partially supported by HSE University Basic Research Program and by Simons–IUM fellowship. The work was done according to FSI SRISA RAS research project No. 0580-2021-0007 (Reg. No. 121031300051-3).
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Lvovski, S. On non-projective small resolutions. European Journal of Mathematics 8, 551–560 (2022). https://doi.org/10.1007/s40879-022-00543-7
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DOI: https://doi.org/10.1007/s40879-022-00543-7