RESEARCH

The Automorphism Group of the Infinite Rank Free Group is Coarsely Bounded [arXiv]
(Joint with G. Domat and H. Hoganson)

Abstract : We prove that the full automorphism group and the outer automorphism group of the free group of countably infinite rank are coarsely bounded. That is, these groups admit no continuous actions on a metric space with unbounded orbits, and have the quasi-isometry type of a point.

Coarse Geometry of Pure Mapping Class Groups of Infinite Graphs [arXiv]
(Joint with G. Domat and H. Hoganson),
Submitted.

Abstract : We discuss the large-scale geometry of pure mapping class groups of locally finite, infinite graphs, motivated by recent work of Algom-Kfir--Bestvina and the work of Mann--Rafi on the large-scale geometry of mapping class groups of infinite-type surfaces. Using the framework of Rosendal for coarse geometry of non-locally compact groups, we classify when the pure mapping class group of a locally finite, infinite graph is globally coarsely bounded (an analog of compact) and when it is locally coarsely bounded (an analog of locally compact).

Our techniques also give lower bounds on the first integral cohomology of the pure mapping class group for some graphs and allow us to compute the asymptotic dimension of all of the locally coarsely bounded pure mapping class groups of infinite rank graphs. This dimension is always either zero or infinite.

Free products from spinning and rotating families [arXiv]
(Joint with M. Bestvina, R. Dickmann, G. Domat, P. Patel, and E. Stark),
Accepted to Enseign. Math.

Abstract : The far-reaching work of Dahmani-Guirardel-Osin and recent work of Clay-Mangahas-Margalit provide geometric approaches to the study of the normal closure of a subgroup (or a collection of subgroups)in an ambient group G. Their work gives conditions under which the normal closure in G is a free product. In this paper we unify their results and simplify and significantly shorten the proof of Dahmani-Guirardel-Osin.

On Translation Length of Anosov Maps on Curve Graph of Torus [Journal] [arXiv]
(Joint with H. Baik, C. Kim, H. Shin), Geom. Dedicata, 214 (2021) Issue 1, pp 399-426

Abstract : We show that an Anosov map has a geodesic axis on the curve graph of a torus. The direct corollary of our result is the stable translation length of an Anosov map on the curve graph is always a positive integer. As the proof is constructive, we also provide an algorithm to calculate the exact translation length for any given Anosov map. The application of our result is threefold:

(a) to determine which word realizes the minimal translation length on the curve graph within a specific class of words,

(b) to establish the effective bound on the ratio of translation lengths of an Anosov map on the curve graph to that on Teichmüller space, and

(c) to estimate the overall growth of the number of Anosov maps which have a sufficient number of Anosov maps with the same translation length.

Slides

Lighting Talk @ 2019 Tech Topology Conference, Georgia Institute of Technology, USA

Lab/Research Seminar

  1. (03/22/2018)Curve complex of Torus

  2. (04/26/2018)Teichmüller space of Torus

  3. (05/10/2018)Hyperbolicity of curve complex

  4. (05/31/2018)Translation length on curve graph

  5. (08/23/2018)Distances in curve graph

  6. (10/02/2018)[Masur-Minsky Series]I. Introduction and main results

  7. (10/31/2018)[Masur-Minsky Series]II. Outline of the proof of hyperbolicity

MAS532, Algebraic Topology II, KAIST

  1. (10/29/2018)Homotopy theory of fiber bundles

*The QR code for the preprint is no longer available.

*Poster template courtesy of Mike Morrison #BetterPoster, and its LaTeX version is due to Rafael Balio.

poster.pdf

Undergraduate Research Program Workshop(2019. 2. 22), KAIST

MAS491, Introduction to Contemporary Mathematics, KAIST