Advanced Studies in Pure Mathematics

A proof of a conjecture of Degtyarev on non-torus plane sextics

Christophe Eyral and Mutsuo Oka

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A $\mathbb{D}_{10}$-sextic is an irreducible sextic $C \subset \mathbb{CP}^2$ with simple singularities such that the fundamental group $\pi_1 (\mathbb{CP}^2 \setminus C)$ factors to the dihedral group $\mathbb{D}_{10}$. A $\mathbb{D}_{10}$-sextic is not of torus type. In this paper, we show that if $C$ is a $\mathbb{D}_{10}$-sextic with the set of singularities $4\mathbf{A}_4$ or $4\mathbf{A}_4 \oplus \mathbf{A}_1$, then $\pi_1 (\mathbb{CP}^2 \setminus C)$ is isomorphic to $\mathbb{D}_{10} \times \mathbb{Z}/3\mathbb{Z}$. This positively answers a conjecture by Degtyarev.

Article information

Singularities — Niigata–Toyama 2007, J.-P. Brasselet, S. Ishii, T. Suwa and M. Vaquie, eds. (Tokyo: Mathematical Society of Japan, 2009), 109-131

Received: 7 December 2007
Revised: 30 May 2008
First available in Project Euclid: 28 November 2018

Permanent link to this document euclid.aspm/1543448014

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Mathematical Reviews number (MathSciNet)

Zentralblatt MATH identifier

Primary: 14H30: Coverings, fundamental group [See also 14E20, 14F35]
Secondary: 14H20: Singularities, local rings [See also 13Hxx, 14B05] 14H45: Special curves and curves of low genus 14H50: Plane and space curves

Fundamental group irreducible non-torus plane sextic


Eyral, Christophe; Oka, Mutsuo. A proof of a conjecture of Degtyarev on non-torus plane sextics. Singularities — Niigata–Toyama 2007, 109--131, Mathematical Society of Japan, Tokyo, Japan, 2009. doi:10.2969/aspm/05610109.

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