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On a classification of irreducible periodic diffeomorphisms on surfaces which commute with certain involution

Norihisa Takahashi, Hiraku Nozawa

TL;DR

The paper addresses the problem of classifying irreducible periodic diffeomorphisms on a genus $g$ surface that commute with an involution $\iota_g$ whose quotient is a torus $T^2$. It develops a framework based on total valency (Nielsen data) and leverages Riemann–Hurwitz, Harvey’s criterion for cyclic coverings, and torus-quotient dynamics to constrain possible lifts. The authors obtain a finite list of conjugacy classes for such irreducible actions, realized by specific generators $h_{n,p}$ (e.g., $h_{6,1}$, $h_{8,1}$, $h_{8,5}$, $h_{12,2}$, $h_{12,3}$) up to conjugacy, and prove the nonexistence of irreducible roots for certain constructed examples $F_1$ and $F_2$. This sharpens the understanding of symmetry groups of surfaces with torus quotients and highlights a marked contrast with Ishizaka’s hyperelliptic (sphere-quotient) classification, by yielding a finite, explicit catalog of possibilities.

Abstract

Ishizaka classified up to conjugacy hyperelliptic periodic automorphisms of a surface. Here, an involution $I$ on a surface $Σ_{g}$ is hyperelliptic if and only if $Σ_{g}/\langle I \rangle$ is homeomorphic to $S^2$. In this article, we give a classification up to conjugacy for irreducible periodic automorphisms of a surface $Σ_{g}$ which commute with involutions $ι$ such that $Σ_{g}/\langle ι\rangle$ is homeomorphic to $T^{2}$.

On a classification of irreducible periodic diffeomorphisms on surfaces which commute with certain involution

TL;DR

The paper addresses the problem of classifying irreducible periodic diffeomorphisms on a genus surface that commute with an involution whose quotient is a torus . It develops a framework based on total valency (Nielsen data) and leverages Riemann–Hurwitz, Harvey’s criterion for cyclic coverings, and torus-quotient dynamics to constrain possible lifts. The authors obtain a finite list of conjugacy classes for such irreducible actions, realized by specific generators (e.g., , , , , ) up to conjugacy, and prove the nonexistence of irreducible roots for certain constructed examples and . This sharpens the understanding of symmetry groups of surfaces with torus quotients and highlights a marked contrast with Ishizaka’s hyperelliptic (sphere-quotient) classification, by yielding a finite, explicit catalog of possibilities.

Abstract

Ishizaka classified up to conjugacy hyperelliptic periodic automorphisms of a surface. Here, an involution on a surface is hyperelliptic if and only if is homeomorphic to . In this article, we give a classification up to conjugacy for irreducible periodic automorphisms of a surface which commute with involutions such that is homeomorphic to .

Paper Structure

This paper contains 5 sections, 25 theorems, 11 equations, 12 figures.

Key Result

Theorem 1.3

Let $I$ and $\iota_g$ be a hyperelliptic involution and an involution of $\Sigma_g$ such that $\Sigma_g/ \langle \iota_g \rangle$ is homeomorphic to a torus (Figure fig:iotag), respectively. For any periodic diffeomorphism $f$ of $\Sigma_{g}$ which commutes with an involution $\iota_g$, if the subgr

Figures (12)

  • Figure 1: An involution $\iota_{g}$ such that $\Sigma_g / \langle \iota_g \rangle$ is homeomorphic to $T^2$
  • Figure 2: A diffeomorphism $h_{n,p}$
  • Figure 3:
  • Figure 5: Glue the boundaries of the complements of disk neighborhoods of the fixed points of $(\Sigma_g, h_{4g,2g})$ and $(\Sigma_g, h_{4g,2g}^{4g-1})$ to obtain a diffeomorphism that commutes with an involution $\iota_{2g+1}$
  • Figure 6:
  • ...and 7 more figures

Theorems & Definitions (43)

  • Example 1.1: Takahashi
  • Example 1.2
  • Theorem 1.3
  • Theorem 2.1: Nielsen Nielsen, see also Ashikaga-Ishizaka, Hirose
  • Proposition 2.2: Nielsen Nielsen
  • Remark 2.3
  • Proposition 2.4: Riemann-Hurwitz formula
  • Proposition 2.5: Harvey Harvey
  • Theorem 2.6: Kasahara Kasahara
  • Theorem 2.7: Wiman, see Hirose-Kasahara
  • ...and 33 more