Generalized torsion for knots with arbitrarily high genus
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 $(2, 2q+1)$ -toru...
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Veröffentlicht in: | Canadian mathematical bulletin 2022-12, Vol.65 (4), p.867-881 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | 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. |
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ISSN: | 0008-4395 1496-4287 |
DOI: | 10.4153/S0008439521000977 |