Homemath.AGarXiv:2605.29624

Superspecial plane quintics with large automorphism groups

math.AGmath.NT2026-05v1license

Abstract

In this paper, we study plane quintic curves whose automorphism groups have order greater than 10, as well as those with cyclic automorphism groups of order 8 and 10. The latter two cases are represented as one-parameter families, where their superspeciality can be explicitly described in terms of a truncation of certain Gaussian hypergeometric series. Applying this characterization, we determine the exact number of isomorphism classes of superspecial plane quintic curves with automorphism groups Z/10Z\cong \mathbb{Z}/10\mathbb{Z}. We also provide an efficient algorithm to enumerate such curves with automorphism groups Z/8Z\cong \mathbb{Z}/8\mathbb{Z}, and provide the computational results for the range 13<p<1000013 < p < 10000.

Comments: 15 pages, comments welcome!

Cite

@article{arxiv.2605.29624,
  title  = {Superspecial plane quintics with large automorphism groups},
  author = {Ryo Ohashi},
  journal= {arXiv preprint arXiv:2605.29624},
  year   = {2026}
}