Published online by Cambridge University Press: 02 December 2021
Let G be a group, and let g be a nontrivial element in G. If some nonempty finite product of conjugates of g equals the identity, then g is called a generalized torsion element. We say that a knot K has generalized torsion if $G(K) = \pi _1(S^3 - K)$ admits such an element. For a
$(2, 2q+1)$-torus knot K, we demonstrate that there are infinitely many unknots
$c_n$ in
$S^3$ such that p-twisting K about
$c_n$ yields a twist family
$\{ K_{q, n, p}\}_{p \in \mathbb {Z}}$ in which
$K_{q, n, p}$ is a hyperbolic knot with generalized torsion whenever
$|p|> 3$. This gives a new infinite class of hyperbolic knots having generalized torsion. In particular, each class contains knots with arbitrarily high genus. We also show that some twisted torus knots, including the
$(-2, 3, 7)$-pretzel knot, have generalized torsion. Because generalized torsion is an obstruction for having bi-order, these knots have non-bi-orderable knot groups.
Dedicated to the memory of Toshie Takata. The first-named author has been partially supported by JSPS KAKENHI Grant Number 19K03502 and Joint Research Grant of the Institute of Natural Sciences at Nihon University for 2021. The second-named author has been supported by JSPS KAKENHI Grant Number 20K03587.