arXiv subjects

Kentaro Ito

Publications and source records attributed to Kentaro Ito.

7 recordsLinked to original sources

arXiv2022

Convex Polyhedra in the $3$-Sphere and Tilings of the $2$-Sphere

We show that for every convex polyhedral sphere $P$ in $S^3$, there exist two canonical, non-edge-to-edge tilings of $S^{2}$ whose tiles are given by all the faces of $P$ and the dual convex polyhedral sphere $P^*$ to $P$. Under the identifications of $S^{3}$ with the Lie group $SU(2)$, and of $S^{2}$ with the unit sphere in the Lie algebra $su(2)$ of $SU(2)$, our result is obtained by considering the set $\widetilde P$ of outward unit normal vectors to $P$ and the maps from $\widetilde P$ to $S^{2}$ defined by using the left and right Maurer-Cartan forms on $SU(2)$.

math.GT↗

arXiv2013

Linear slices close to a Maskit slice

We consider linear slices of the space of Kleinian once-punctured torus groups; a linear slice is obtained by fixing the value of the trace of one of the generators. The linear slice for trace 2 is called the Maskit slice. We will show that if traces converge `horocyclically' to 2 then associated linear slices converge to the Maskit slice, whereas if the traces converge `tangentially' to 2 the linear slices converge to a proper subset of the Maskit slice. This result will be also rephrased in terms of complex Fenchel-Nielsen coordinates. In addition, we will show that there is a linear slice which is not locally connected.

math.GT↗

arXiv2011

Convergence and divergence of Kleinian punctured torus groups

In this paper we give a necessary and sufficient condition in which a sequence of Kleinian punctured torus groups converges. This result tells us that every exotically convergent sequence of Kleinian punctured torus groups is obtained by the method due to Anderson and Canary. Thus we obtain a complete description of the set of points at which the space of Kleinian punctured torus groups self-bumps. We also discuss geometric limits of sequences of Bers slices.

math.GT↗

arXiv2011

Convergence Properties for the Physarum Solver

The Physarum solver is an intuitive mechanism for solving optimisation problems based on the idea of an electrical network, whereby the conductivity is reinforced by the current. We show that the Physarum solver obtains the solution to the linear transshipment problem on a digraph and that the electrical potential converges to an infinity-harmonic solution of the dual problem.

math.OC↗

arXiv2008

An extension of the Maskit slice for 4-dimensional Kleinian groups

Let $Γ$ be a 3-dimensional Kleinian punctured torus group with ccidental parabolic transformations. The deformation space of $Γ$ in the group of Möbius transformations on the 2-sphere is well-known as the Maskit slice of punctured torus groups. In this paper, we study deformations $Γ'$ of $Γ$ in the group of Möbius transformations on the 3-sphere such that $Γ'$ does not contain screw parabolic transformations. We will show that the space of the deformations is realized as a domain of 3-space $\mathbb{R}^3$, which contains the Maskit slice of punctured torus groups as a slice through a plane. Furthermore, we will show that the space also contains the Maskit slice of fourth-punctured sphere groups as a slice through another plane. Some of another slices of the space will be also studied.

math.GT↗

arXiv2006

Exotic projective structures and quasifuchsian spaces II

Let $P(S)$ be the space of projective structures on a closed surface $S$ of genus $g >1$ and let $Q(S)$ be the subset of $P(S)$ of projective structures with quasifuchsian holonomy. It is known that $Q(S)$ consists of infinitely many connected components. In this paper, we will show that the closure of any exotic component of $Q(S)$ is not a topological manifold with boundary and that any two components of $Q(S)$ have intersecting closures.

math.GT↗

arXiv2004

On continuous extension of grafting maps

The definition of the grafting operation for quasifuchsian groups is extended by Bromberg to all $b$-groups. Although the grafting maps are not necessarily continuous at boundary groups, in this paper, we show that the grafting maps take every "standard" convergent sequence to a convergent sequence. As a consequence of this result, we extend Goldman's grafting theorem for quasifuchsian groups to all boundary $b$-groups.

math.GT↗