The Maschke octic contains 96 pairwise disjoint lines

Authors

  • Cédric Bonnafé IMAG, Université de Montpellier, CNRS, Montpellier, France

DOI:

https://doi.org/10.56754/0719-0646.2803.449

Keywords:

Lines in surfaces, skew lines, reflection groups

Abstract

Miyaoka proved that a smooth surface of degree \(d\) in \(\mathbf{P}^3(\mathbb{C})\) contains at most \(2d(d-2)\) pairwise disjoint lines. In this note, we verify that the Maschke octic contains 96 pairwise disjoint lines, thereby proving that Miyaoka's bound is optimal for \(d=8\).

Downloads

Download data is not yet available.

References

[1] W. Barth, "Two projective surfaces with many nodes, admitting the symmetries of the icosahedron," J. Algebr. Geom., vol. 5, no. 1, pp. 173–186, 1996.

[2] S. Boissière and A. Sarti, "Counting lines on surfaces," Ann. Sc. Norm. Super. Pisa, Cl. Sci. (5), vol. 6, no. 1, pp. 39–52, 2007.

[3] C. Bonnafé, "Some singular curves and surfaces arising from invariants of complex reflection groups," Exp. Math., vol. 30, no. 3, pp. 429–440, 2021, doi: 10.1080/10586458.2018.1555778.

[4] C. Bonnafé, "A dodecic surface with 320 cusps," Bulletin of the Polish Academy of Sciences. Mathematics, 2026, doi: 10.4064/ba251219-8-5.

[5] C. Bonnafé and A. Sarti, "Complex reflection groups and K3 surfaces. II: The groups G29, G30 and G31," J. Korean Math. Soc., vol. 60, no. 4, pp. 695–743, 2023, doi: 10.4134/JKMS.j220014.

[6] C. Bonnafé, "maschkeoctic," GitHub. 2026. [Source Code]. Available at: https://github.com/CedricBonnafe/maschkeoctic [Accessed: Sep. 1 2026].

[7] W. Bosma, J. Cannon, and C. Playoust, "The Magma algebra system. I: The user language," J. Symb. Comput., vol. 24, no. 3-4, pp. 235–265, 1997, doi: 10.1006/jsco.1996.0125.

[8] H. Maschke, "Ueber die quaternäre, endliche, lineare Substitutionsgruppe der Borchardt’schen Moduln." Math. Ann., vol. 30, pp. 496–515, 1887, doi: 10.1007/BF01444092.

[9] Y. Miyaoka, "The maximal number of quotient singularities on surfaces with given numerical invariants," Math. Ann., vol. 268, pp. 159–171, 1984, doi: 10.1007/BF01456083.

[10] S. Rams, "Three-divisible families of skew lines on a smooth projective quintic," Trans. Am. Math. Soc., vol. 354, no. 6, pp. 2359–2367, 2002, doi: 10.1090/S0002-9947-02-02979-3.

[11] S. Rams, "Projective surfaces with many skew lines," Proc. Am. Math. Soc., vol. 133, no. 1, pp. 11–13, 2005, doi: 10.1090/S0002-9939-04-07519-7.

[12] A. Sarti, "Pencils of symmetric surfaces in P3." J. Algebra, vol. 246, no. 1, pp. 429–452, 2001, doi: 10.1006/jabr.2001.8953.

[13] G. C. Shephard and J. A. Todd, "Finite unitary reflection groups," Can. J. Math., vol. 6, pp. 274–304, 1954, doi: 10.4153/CJM-1954-028-3.

Downloads

Published

2026-09-16

How to Cite

[1]
C. Bonnafé, “The Maschke octic contains 96 pairwise disjoint lines”, CUBO, vol. 28, no. 3, pp. 449–453, Sep. 2026.

Issue

Section

Articles

Similar Articles

1 2 3 4 5 6 > >> 

You may also start an advanced similarity search for this article.