activity
19982023
most citedRealising end invariants by limits of minimally parabolic, geometrically finite groups

31 citations · 43 across the 23 of their papers we have counts for

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24 papers · 1 filter

math.GT2023

On the Teichm{ü}ller space of acute triangles

Hideki Miyachi, Ken'Ichi Ohshika, Athanase Papadopoulos

We continue the study of the analogue of Thurston's metric on the Teichm{ü}ller space of Euclidean triangle which was started by Saglam and Papadopoulos in [1].By direct calculatio…

math.GT2023

Thurston's broken windows only theorem revisited

Ken'ichi Ohshika

The'broken windows only theorem' is the main theorem of the third paper among a series of the paper in which Thurston proved his uniformisation theorem for Haken manifolds. In this…

math.GT2022

Thurston's Bounded image theorem

Cyril Lecuire, Ken'ichi Ohshika

Thurston's bounded image theorem is one of the key steps in his proof of the uniformisation theorem for Haken manifolds. Thurston never published its proof, and no proof has been k…

math.GT2021★ 1 cited

The infinitesimal and global Thurston geometry of Teichm{ü}ller space

Yi Huang, Ken'Ichi Ohshika, Athanase Papadopoulos

We undertake a systematic study of the infinitesimal geometry of the Thurston metric, showing that the topology, convex geometry and metric geometry of the tangent and cotangent sp…

math.GT2021

Realisation of bending measured laminations by Kleinian surface groups

Shinpei Baba, Ken'ichi Ohshika

For geometrically finite Kleinian surface groups, Bonahon and Otal proved the existence part, and partly the uniqueness part of the bending lamination conjecture. In this paper, we…

math.GT2020

A glimpse into Thurston's work

Ken'Ichi Ohshika, Athanase Papadopoulos

We present an overview of some significant results of Thurston and their impact on mathematics. The final version of this paper will appear as Chapter 1 of the book "In the traditi…

math.GT2020

Shapes of hyperbolic triangles and once-punctured torus groups

Sang-hyun Kim, Thomas Koberda, Jaejeong Lee +3

Let be a hyperbolic triangle with a fixed area . We prove that for all but countably many , generic choices of have the property that the group generated by the --…

math.GT2020

Classification of non-free Kleinian groups generated by two parabolic transformations

Hirotaka Akiyoshi, Ken'ichi Ohshika, John Parker +2

We give a full proof to Agol's announcement on the classification of non-free Kleinian groups generated by two parabolic transformations.

math.GT2018

Bijections of geodesic lamination space preserving left Hausdorff convergence

Ken'Ichi Ohshika, Athanase Papadopoulos

We introduce an asymmetric distance function, which we call the `left Hausdorff distance function', on the space of geodesic laminations on a closed hyperbolic surface of genus at…

math.GT2018

Homeomorphisms and intersection number

Ken'Ichi Ohshika, Athanase Papadopoulos

We prove two rigidity results for automorphism groups of the spaces ML(S) of measured laminations on a closed hyperbolic surface S and PML(S) of projective measured laminations on…

math.GT2017★ 3 cited

Discontinuous motions of limit sets

Mahan Mj, Ken'ichi Ohshika

We characterise completely when limit sets, as parametrised by Cannon-Thurston maps, move discontinuously for a sequence of algebraically convergent quasi-Fuchsian groups.

math.GT2014★ 1 cited

Measurable Rigidity for Kleinian groups

Woojin Jeon, Ken'ichi Ohshika

Let be two Kleinian groups with homeomorphic quotients and . We assume that is of divergence type, and consider the Patterson-Sullivan mea…

math.GT2013

Primitive stable closed hyperbolic 3-manifolds

Inkang Kim, Cyril Lecuire, Ken'ichi Ohshika

We show that closed 3-manifolds with high Heegaard distance and bounded subsurface Heegaard distance are primitive stable when they are regarded as representations from the free gr…

math.GT2013★ 2 cited

Subgroups of mapping class groups related to Heegaard splittings and bridge decompositions

Ken'ichi Ohshika, Makoto Sakuma

Let be a Heegaard splitting of a closed orientable 3-manifold (or a bridge decomposition of a link exterior). Consider the subgroup of t…

math.GT2013

Conical limit sets of hyperbolic subgroups

Woojin Jeon, Ken'ichi Ohshika

Given a hyperbolic subgroup of a hyperbolic group for which a Cannon-Thurston map $\hat i:\partial H \ra \partial G$ exists, we study the limit set of with respec…

math.GT2011

A note on the rigidity of unmeasured lamination spaces

Ken'ichi Ohshika

We show that every auto-homeomorphism of the unmeasured lamination space of an orientable surface of finite type is induced by a unique extended mapping class unless the surface is…

math.GT2011★ 2 cited

Reduced Bers boundaries of Teichmüller spaces

Ken'ichi Ohshika

We consider a quotient space of the Bers boundary of Teichmüller space, which we call the reduced Bers boundary, by collapsing each quasi-conformal deformation space into a point.…

math.GT2010

Divergence, exotic convergence and self-bumping in quasi-Fuchsian spaces

Ken'ichi Ohshika

In this paper, we study the topology of the boundaries of quasi-Fuchsian spaces. We first show for a given convergent sequence of quasi-Fuchsian groups, how we can know the end inv…

math.GT2010

Primitive stable representations of free Kleinian groups

W. Jeon, I. Kim, K. Ohshika with C. Lecuire

In this paper, we give a complete criterion for a discrete faithful representation $ρ:F_n \ra \pslc$ to be primitive stable. This will answer Minsky's conjectures about geometric c…

math.GT2010

Geometry and topology of geometric limits I

Ken'ichi Ohshika, Teruhiko Soma

In this paper, we classify completely hyperbolic 3-manifolds corresponding to geometric limits of Kleinian surface groups isomorphic to for a finite-type hyperbolic surfac…

math.GT2008

Constructing geometrically infinite groups on boundaries of deformation spaces

Ken'ichi Ohshika

Consider a geometrically finite Kleinian group without parabolic or elliptic elements, with its Kleinian manifold $M=(\H^3\cup Ω_G)/G$. Suppose that for each boundary component…

math.GT2007

Convergence of freely decomposable Kleinian groups

Inkang Kim, Cyril Lecuire, Ken'ichi Ohshika

We consider a compact orientable hyperbolic 3-manifold with a compressible boundary. Suppose that we are given a sequence of geometrically finite hyperbolic metrics whose conformal…

math.GT2005★ 31 cited

Realising end invariants by limits of minimally parabolic, geometrically finite groups

Ken'ichi Ohshika

We shall show that for a given homeomorphism type and a set of end invariants (including the parabolic locus) with necessary topological conditions which a topologically tame Klein…

math.GT1998

Divergent sequences of Kleinian groups

Ken'ichi Ohshika

One of the basic problems in studying topological structures of deformation spaces for Kleinian groups is to find a criterion to distinguish convergent sequences from divergent seq…