Presentations of the cactus Thompson group
We give infinite and finite presentations of the cactus Thompson group. This group was introduced as $V_{\mathrm{mock}}$ by Witzel and Zaremsky, who combined Thompson's group with cactus groups.
math.GR↗
arXiv subjects
Yuya Kodama
Publications and source records attributed to Yuya Kodama.
Distorted and undistorted subgroups of the Lodha-Moore group
We show that the Baumslag-Solitar group $BS(1,2)$ is undistorted in the Lodha-Moore group $G_0$ using an explicit lower bound for the word length of $G_0$. We also show that Thompson's group $F$ is distorted in $G_0$.
math.GR↗
Metrics for quandles
A quandle is an algebraic system originating in knot theory, which can be regarded as a generalization of the conjugation of groups. This structure naturally defines two subgroups of its automorphism group, which are called the inner automorphism group and the displacement group, and they act on the quandle from the right. For a quandle with such groups being finitely generated, we investigate the graph structures induced from the actions, and induced metric spaces. The graph structures are defined by the notion of the Schreier graph, which is a natural generalization of the Cayley graph for a group. In particular, the metric associated with the displacement group for an important class of quandles, namely, generalized Alexander quandles, is studied in detail. We show that such a metric space is quasi-isometric to the displacement group with a word metric. Finally, we provide some examples quasi-isometric to typical metric spaces.
math.GT↗
The Lodha--Moore groups and their $n$-adic generalizations are not SCY
A closed 4-manifold is symplectic Calabi--Yau (SCY) if its canonical class is trivial. Friedl and Vidussi proved that Thompson's group $F$ cannot be the fundamental group of any SCY manifold. In this paper, we show that its generalizations, called the Brown--Thompson group and the $n$-adic Lodha--Moore groups, cannot be also the fundamental group of any SCY manifold by using their method. From this proof, we also show that there exist non-trivial infinitely many examples which satisfy Geoghegan's conjecture.
math.GT↗
Divergence functions of higher-dimensional Thompson's groups
We prove that higher-dimensional Thompson's groups have linear divergence functions. By the work of Druţu, Mozes, and Sapir, this implies none of the asymptotic cones of $nV$ has a cut-point.
math.GR↗
An $n$-adic generalization of the Lodha-Moore group
We generalized the Lodha-Moore group into $n$-adic and showed analogues in the Lodha-Moore group of properties between the Thompson group $F$ and the generalized Thompson group $F(n)$.
math.GR↗
Divergence function of the braided Thompson group
We prove that the braided Thompson group $BV$ has a linear divergence function. By the work of Druţu, Mozes, and Sapir, this leads none of asymptotic cones of $BV$ has a cut-point.
math.GR↗
Alexander's theorem for stabilizer subgroups of Thompson's group
In 2017, Jones studied the unitary representations of Thompson's group $F$ and defined a method to construct knots and links from $F$. One of his results is that any knot or link can be obtained from an element of this group, which is called Alexander's theorem. On the other hand, Thompson's group $F$ has many subgroups and it is known that there exist various subgroups which satisfy or do not satisfy Alexander's theorem. In this paper, we prove that almost all stabilizer subgroups under the natural action on the unit interval satisfy Alexander's theorem.
math.GT↗
Virtual Thompson's group
For virtual knot theory, the virtual braid group was defined by generalizing the braid group. It was proved that any virtual link can be obtained by the closure of a virtual braid. On the other hand, due to work by Jones et al., it is known that any (oriented) link is constructed from an element of Thompson's group $F$. In this paper, we define the ``virtual version'' of Thompson's group $F$ and prove that any virtual link is constructed from an element of the group.
math.GT↗
The $p$-colorable subgroup of Thompson's group
Recently, Jones introduced a method of constructing knots and links from elements of Thompson's group $F$ by using its unitary representations. He also defined several subgroups of $F$ as the stabilizer subgroups and some researchers studied them algebraically. One of the subgroups is called the 3-colorable subgroup $\mathcal{F}$, and the authors proved that all knots and links obtained from non-trivial elements of $\mathcal{F}$ are 3-colorable. In this paper, for any odd integer $p$ greater than two, we define the $p$-colorable subgroup of $F$ whose non-trivial elements yield $p$-colorable knots and links and show it is isomorphic to the certain Brown--Thompson group.
math.GR↗
The $3$-colorable subgroup of Thompson's group and tricolorability of links
Starting from the work by Jones on representations of Thompson's group $F$, subgroups of $F$ with interesting properties have been defined and studied. One of these subgroups is called the $3$-colorable subgroup $\mathcal{F}$, which consists of elements whose ``regions'' given by their tree diagrams are $3$-colorable. On the other hand, in his work on representations, Jones also gave a method to construct knots and links from elements of $F$. Therefore it is a natural question to explore a relationship between elements in $\mathcal{F}$ and $3$-colorable links in the sense of knot theory. In this paper, we show that all elements in $\mathcal{F}$ give 3-colorable links.
math.GT↗