English

Deforming Calabi-Yau Threefolds

alg-geom 2025-10-10 v2 Algebraic Geometry

Abstract

This paper first generalises the Bogomolov-Tian-Todorov unobstructedness theorem to the case of Calabi-Yau threefolds with canonical singularities. The deformation space of such a Calabi-Yau threefold is no longer smooth, but the general principle is that the obstructions to deforming such a threefold are precisely the obstructions to deforming the singularities of the threefold. Secondly, these results are applied to smoothing singular Calabi-Yau threefolds with crepant resolutions. Any such Calabi-Yau threefold with isolated complete intersection singularities which are not ordinary double points is smoothable. A Calabi-Yau threefold with non-complete intersection isolated singularities is proved to be smoothable under much stronger hypotheses.

Keywords

Cite

@article{arxiv.alg-geom/9506022,
  title  = {Deforming Calabi-Yau Threefolds},
  author = {Mark Gross},
  journal= {arXiv preprint arXiv:alg-geom/9506022},
  year   = {2025}
}

Comments

Post-publication revision, correcting one error and clarifying an aspect of the proof of Theorem 2.2

R2 v1 2026-07-22T07:41:51.940Z