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Hurwitz equivalence in the universal dihedral quandle

Takuji Nakamura, Yasutaka Nakanishi, Shin Satoh, Kodai Wada

Abstract

We investigate the Hurwitz action of the $m$-braid group on the $m$-fold Cartesian product of the universal dihedral quandle. We introduce three computable invariants and prove that they give a complete classification of the orbits under this action. As a consequence, we describe an explicit complete system of orbit representatives. We further obtain analogous classifications for the corresponding Hurwitz actions of the pure $m$-braid group, the virtual $m$-braid group, and the virtual pure $m$-braid group.

Hurwitz equivalence in the universal dihedral quandle

Abstract

We investigate the Hurwitz action of the -braid group on the -fold Cartesian product of the universal dihedral quandle. We introduce three computable invariants and prove that they give a complete classification of the orbits under this action. As a consequence, we describe an explicit complete system of orbit representatives. We further obtain analogous classifications for the corresponding Hurwitz actions of the pure -braid group, the virtual -braid group, and the virtual pure -braid group.

Paper Structure

This paper contains 7 sections, 33 theorems, 132 equations, 10 figures.

Key Result

Theorem 1.1

For $v,w\in(R_{\infty})^m$ with $m\geq 2$, the following are equivalent.

Figures (10)

  • Figure 2.1: The Hurwitz action of $B_{m}$ on $\mathbb{Z}^{m}$
  • Figure 4.1: Proof of Lemma \ref{['lem41']}
  • Figure 4.2: The braid $\sigma_1\sigma_2^2\sigma_1$
  • Figure 4.3: Three braids $\beta$, $\beta'$, and $\beta"$
  • Figure 4.4: The braid $\sigma_{2k-3}\sigma_{2k-2}^2\sigma_{2k-3}$
  • ...and 5 more figures

Theorems & Definitions (63)

  • Theorem 1.1
  • Theorem 1.2
  • Theorem 1.3
  • Theorem 1.4
  • Lemma 2.1
  • proof
  • Lemma 2.2
  • proof
  • Lemma 2.3
  • proof
  • ...and 53 more