Konstantinos Tsouvalas

activity

20192026

most citedTopological restrictions on Anosov representations

19 citations · 23 across the 18 of their papers we have counts for

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16 papers · 1 filter

math.GR2026

Nonarchimedean discrete groups and quasi-isometric doubles of free groups

Konstantinos Tsouvalas

For any nonarchimedean local field $k$ , we exhibit the first examples of Zariski-dense, discrete subgroups of special linear groups over $k$ , which are not commensurable to any lat…

math.GR2026

On transversality in flag manifolds and linearity of amalgams

Sami Douba, Konstantinos Tsouvalas

We show that the fundamental group of the double of a complete negatively curved locally symmetric manifold along a closed geodesic is linear. More generally, we establish linearit…

math.GR2026

Directional growth of coamenable normal subgroups: counterexamples and rigidity

Subhadip Dey, Hee Oh, Konstantinos Tsouvalas

Roblin's theorem asserts that, in rank one, a coamenable normal subgroup has the same critical exponent as its ambient group. Natural higher-rank analogues would predict that coame…

math.GR2026

Robust quasi-isometric embeddings of virtually free groups

Konstantinos Tsouvalas

Let $k$ be a nonarchimedean local field. For any $n \geq 3$ , we construct the first examples of robust quasi-isometric embeddings of non-elementary free groups into $\mathsf{GL}_n(k…

math.GR2026

Matrix entries, unipotents, and linearity of amalgams

Sami Douba, Konstantinos Tsouvalas

We investigate linearity of amalgams of subgroups of algebraic groups along intersections with algebraic subgroups. In the process, we establish linearity of certain "doubles" of l…

math.GR2025

Undecidability of epimorphisms onto products of hyperbolic groups

Konstantinos Tsouvalas

We exhibit examples of finitely presented subgroups $P$ of direct products of hyperbolic groups for which there is no algorithm that detects whether a finitely presented group has…

math.GR2025

Ping-pong in the projective plane over a nonarchimedean field

Sami Douba, Dmitry Kubrak, Konstantinos Tsouvalas

We show that any lattice in $SL_{3} (k)$ , where $k$ is a nonarchimedean local field, contains an undistorted subgroup isomorphic to the free product $Z^{2} * Z$ …

math.GR2025

Anosov representations of amalgams

Subhadip Dey, Konstantinos Tsouvalas

For uniform lattices $Γ$ in rank 1 Lie groups, we construct Anosov representations of virtual doubles of $Γ$ along certain quasiconvex subgroups. We also show that virtual HNN exte…

math.GR2024

Subgroups of CAT(0) groups, exotic finiteness properties and non-QI-embeddings into linear groups

Claudio Llosa Isenrich, Konstantinos Tsouvalas

For every positive integer $n$ we construct an example of a subgroup $L < G$ of a linear $CAT (0)$ group $G$ such that $L$ is of finiteness type $F_{n - 1}$ and not $\m…

math.GR2024

Singular value gap estimates for free products of semigroups

Konstantinos Tsouvalas, Theodore Weisman

We establish lower estimates for singular value gaps of free products of $1$ -divergent semigroups $Γ_{1}, Γ_{2} \subset GL_{d} (K)$ which are in ping-pong position. As an…

math.GR2024

Robust quasi-isometric embeddings inapproximable by Anosov representations

Konstantinos Tsouvalas

Let $K = R$ or $C$ . For all but finitely many $m \in N$ , we exhibit the first examples of non-locally rigid, Zariski dense, robust quasi-isometric…

math.GR2024

Topological restrictions on relatively Anosov representations

Konstantinos Tsouvalas, Feng Zhu

We obtain restrictions on which groups can admit relatively Anosov representations into specified target Lie groups, by examining the topology of possible Bowditch boundaries and h…

math.GR2023

On regular subgroups of $SL_{3} (R)$

Sami Douba, Konstantinos Tsouvalas

Motivated by a question of M. Kapovich, we show that the $Z^{2}$ subgroups of $SL_{3} (R)$ that are regular in the language of Kapovich--Leeb--Porti, or diver…

math.GR2022

Anosov groups that are indiscrete in rank one

Sami Douba, Konstantinos Tsouvalas

We exhibit Anosov subgroups of $SL_{d} (R)$ that do not embed discretely in any rank- $1$ simple Lie group of noncompact type, or indeed, in any finite product of suc…

math.GR2022

Cartan projections of fiber products and non quasi-isometric embeddings

Konstantinos Tsouvalas

Let $Γ$ be a finitely generated group and $N$ be a normal subgroup of $Γ$ . The fiber product of $Γ$ with respect to $N$ is the subgroup $Γ \times_{N} Γ = {(γ, γ w) : γ \in Γ, w \in N}$ o…

math.GR2021

Fiber products of rank 1 superrigid lattices and quasi-isometric embeddings

Konstantinos Tsouvalas

Let $Δ$ be a cocompact lattice in $Sp (m, 1)$ , $m \geq 2$ , or $F_{4}^{(- 20)}$ . We exhibit examples of finitely generated subgroups of $Δ \times Δ$ with positive first Betti n…

Nonarchimedean discrete groups and quasi-isometric doubles of free groups

On transversality in flag manifolds and linearity of amalgams

Directional growth of coamenable normal subgroups: counterexamples and rigidity

Robust quasi-isometric embeddings of virtually free groups

Matrix entries, unipotents, and linearity of amalgams

Undecidability of epimorphisms onto products of hyperbolic groups

Ping-pong in the projective plane over a nonarchimedean field

Anosov representations of amalgams

Subgroups of CAT(0) groups, exotic finiteness properties and non-QI-embeddings into linear groups

Singular value gap estimates for free products of semigroups

Robust quasi-isometric embeddings inapproximable by Anosov representations

Topological restrictions on relatively Anosov representations

On regular subgroups of SL3​(R)

Anosov groups that are indiscrete in rank one

Cartan projections of fiber products and non quasi-isometric embeddings

Fiber products of rank 1 superrigid lattices and quasi-isometric embeddings

On regular subgroups of $SL_{3} (R)$