Sang-hyun Kim

activity

20122026

most citedAlgebraic Structure of Diffeomorphism Groups of One-Manifolds

2 citations · 2 across the 7 of their papers we have counts for

collaborators

13 papers

math.GR2026

Hyperbolicity and obstructions to PL actions of the circle

Leonardo Dinamarca, Maximiliano Escayola, Sang-hyun Kim +1

We investigate acylindrically hyperbolic groups acting on the circle by piecewise linear homeomorphisms. We prove that a finitely generated acylindrically hyperbolic group acting f…

math.GR2026

Small growth rates of free groups

Koji Fujiwara, Sang-hyun Kim, Ryokichi Tanaka

We introduce the notion of a Magnus marking for a finite generating set of a group and prove a certain expansion property. Using this property, we determine the second and third sm…

math.GR2025

Elementary equivalence and diffeomorphism groups of smooth manifolds

Sang-hyun Kim, Thomas Koberda, J. de la Nuez González

Let $M$ and $N$ be smooth manifolds, with $M$ closed and connected. If the $C^{r}$ --diffeomorphism group of $M$ is elementarily equivalent to the $C^{s}$ --diffeomorphism group of $N$ f…

math.GR2021

Structure and regularity of group actions on one-manifolds

Sang-hyun Kim, Thomas Koberda

In this monograph, we give an account of the relationship between the algebraic structure of finitely generated and countable groups and the regularity with which they act on manif…

math.GR2020

Direct products, overlapping actions, and critical regularity

Sang-hyun Kim, Thomas Koberda, Cristóbal Rivas

We address the problem of computing the critical regularity of groups of homeomorphisms of the interval. Our main result is that if $H$ and $K$ are two non-solvable groups then a f…

math.GT2020

Shapes of hyperbolic triangles and once-punctured torus groups

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

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