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- THOMAS KOBERDA, T. KOBERDA
- 2012

Consider the mapping class group Modg,p of a surface Σg,p of genus g with p punctures, and a finite collection {f1,. .. , f k } of mapping classes, each of which is either a Dehn twist about a simple closed curve or a pseudo-Anosov homeomorphism supported on a connected subsurface. In this paper we prove that for all sufficiently large N , the mapping… (More)

- THOMAS KOBERDA
- 2011

In this article we study the right-angled Artin subgroups of a given right-angled Artin group. Starting with a graph Γ, we produce a new graph through a purely combinatorial procedure, and call it the extension graph Γ e of Γ. We produce a second graph Γ e k , the clique graph of Γ e , by adding an extra vertex for each complete subgraph of Γ e. We prove… (More)

- THOMAS KOBERDA, T. KOBERDA
- 2009

We study the action of the mapping class group on the integral homology of finite covers of a topological surface. We use the homological representation of the mapping class to construct a faithful infinite–dimensional representation of the mapping class group. We show that this representation detects the Nielsen–Thurston classification of each mapping… (More)

We prove that finitely generated purely loxodromic subgroups of a right-angled Artin group A(Γ) fulfill equivalent conditions that parallel characterizations of convex cocompactness in mapping class groups Mod(S). In particular, such subgroups are quasiconvex in A(Γ). In addition, we identify a milder condition for a finitely generated subgroup of A(Γ) that… (More)

- THOMAS KOBERDA, RAMANUJAN SANTHAROUBANE
- 2016

We prove that for each sufficiently complicated orientable surface S , there exists an infinite image linear representation ρ of π 1 (S) such that if γ ∈ π 1 (S) is freely homotopic to a simple closed curve on S , then ρ(γ) has finite order. Furthermore, we prove that given a sufficiently complicated orientable surface S , there exists a regular finite… (More)

Let p : Σ ′ → Σ be a finite Galois cover, possibly branched, with Galois group G. We are interested in the structure of the cohomology of Σ ′ as a module over G. We treat the cases of branched and unbranched covers separately. In the case of branched covers, we give a complete classification of possible module structures of H1(Σ ′ , C). In the unbranched… (More)

- Thomas Koberda, T. KOBERDA
- 2011

In this article we study the space of left-and bi-invariant orderings on a torsion-free nilpotent group G. We will show that generally the set of such orderings is equipped with a faithful action of the automorphism group of G. We prove a result which allows us to establish the same conclusion when G is assumed to be merely residually torsion-free… (More)

- HYUNGRYUL BAIK, THOMAS KOBERDA, T. KOBERDA
- 2016

We show that no finite index subgroup of a sufficiently complicated mapping class group or braid group can act faithfully by C 1`bv diffeomorphisms on the circle, which generalizes a result of Farb–Franks, and which parallels a result of Ghys and Burger–Monod concerning differentiable actions of higher rank lattices on the circle. This answers a question of… (More)

- Sang-Hyun Kim, Thomas Koberda
- IJAC
- 2014

- THOMAS KOBERDA, T. KOBERDA
- 2011

We study the residual properties of geometric 3–manifold groups. In particular, we study conditions under which geometric 3–manifold groups are virtually residually p for a prime p, and conditions under which they are residually torsion–free nilpotent. We show that for every prime p, every geometric 3–manifold group is virtually residually p. We show that… (More)