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Related papers: Automatic continuity of pure mapping class groups

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We show that the pure mapping class group is uniformly perfect for a certain class of infinite type surfaces with noncompact boundary components. We then combine this result with recent work in the remaining cases to give a complete…

Geometric Topology · Mathematics 2023-09-13 Ryan Dickmann

We prove that, for any infinite-type surface $S$, the integral homology of the closure of the compactly-supported mapping class group $\overline{\mathrm{PMap}_c(S)}$ and of the Torelli group $\mathcal{T}(S)$ is uncountable in every positive…

Geometric Topology · Mathematics 2025-01-07 Martin Palmer , Xiaolei Wu

We show that the closure of the compactly supported mapping class group of an infinite type surface is not perfect and that its abelianization contains a direct summand isomorphic to an uncountable direct sum of rationals. We also extend…

Geometric Topology · Mathematics 2021-04-26 George Domat , Ryan Dickmann

We provide a complete classification of when the homeomorphism group of a stable surface, $\Sigma$, has the automatic continuity property: Any homomorphism from Homeo$(\Sigma)$ to a separable group is necessarily continuous. This result…

Geometric Topology · Mathematics 2024-11-21 Mladen Bestvina , George Domat , Kasra Rafi

For any infinite-type surface $S$, a natural question is whether the homology of its mapping class group contains any non-trivial classes that are supported on (i) a compact subsurface or (ii) a finite-type subsurface. Our purpose here is…

Geometric Topology · Mathematics 2025-09-16 Martin Palmer , Xiaolei Wu

Let $S$ be an orientable, connected surface with infinitely-generated fundamental group. The main theorem states that if the genus of $S$ is finite and at least 4, then the isomorphism type of the pure mapping class group associated to $S$,…

Geometric Topology · Mathematics 2018-12-19 Priyam Patel , Nicholas G. Vlamis

We investigate the problem of when big mapping class groups are generated by involutions. Restricting our attention to the class of self-similar surfaces, which are surfaces with self-similar ends space, as defined by Mann and Rafi, and…

Geometric Topology · Mathematics 2021-10-25 Justin Malestein , Jing Tao

We show that the extended based mapping class group of an infinite-type surface is naturally isomorphic to the automorphism group of the loop graph of that surface. Additionally, we show that the extended mapping class group stabilizing a…

Geometric Topology · Mathematics 2019-12-17 Anschel Schaffer-Cohen

We extend the proof of automatic continuity for homeomorphism groups of manifolds to non-compact manifolds and manifolds with marked points and their mapping class groups. Specifically, we show that, for any manifold $M$ homeomorphic to the…

Geometric Topology · Mathematics 2020-03-04 Kathryn Mann

Let S be any orientable surface of infinite genus with a finite number of boundary components. In this work we consider the curve complex C(S), the nonseparating curve complex N(S) and the Schmutz graph G(S) of S. When all the topological…

Geometric Topology · Mathematics 2014-02-14 Jesús Hernández Hernández , José Ferrán Valdez Lorenzo

We show that any homomorphism from the homeomorphism group of a compact 2-manifold, with the compact-open topology, or equivalently, with the topology of uniform convergence, into a separable topological group is automatically continuous.

Geometric Topology · Mathematics 2007-05-23 Christian Rosendal

We show that continuous epimorphisms between a class of subgroups of mapping class groups of orientable infinite-genus 2-manifolds with no planar ends are always induced by homeomorphisms. This class of subgroups includes the pure mapping…

Geometric Topology · Mathematics 2026-02-06 Javier Aramayona , Rodrigo De Pool , Rachel Skipper , Jing Tao , Nicholas G. Vlamis , Xiaolei Wu

It is a classical result of Powell that pure mapping class groups of connected, orientable surfaces of finite type and genus at least three are perfect. In stark contrast, we construct nontrivial homomorphisms from infinite-genus mapping…

Geometric Topology · Mathematics 2024-03-11 Javier Aramayona , Priyam Patel , Nicholas G. Vlamis

We study when the mapping class group of an infinite-type surface $S$ admits an action with unbounded orbits on a connected graph whose vertices are simple closed curves on $S$. We introduce a topological invariant for infinite-type…

Geometric Topology · Mathematics 2024-03-11 Matthew Gentry Durham , Federica Fanoni , Nicholas G. Vlamis

We give an infinite presentation for the mapping class group of a non-orientable surface with boundary components. The presentation is a generalization of the presentation given by the second author [15].

Geometric Topology · Mathematics 2016-10-18 Ryoma Kobayashi , Genki Omori

We show that the natural map from the mapping class groups of surfaces to the automorphism groups of free groups, induces an infinite loop map on the classifying spaces of the stable groups after plus construction. The proof uses…

Algebraic Topology · Mathematics 2008-01-15 Nathalie Wahl

The mapping class group of a non-exceptional oriented surface of finite type admits a biautomatic structure.

Group Theory · Mathematics 2009-12-02 Ursula Hamenstaedt

In this note we prove that the mapping class group of a compact topological manifold $M$ with boundary is of finite type, under assumptions on its dimension and connectivity.

Geometric Topology · Mathematics 2024-04-04 Alexander Kupers

We prove that the mapping class group of a surface obtained from removing a Cantor set from either the 2-sphere, the plane, or the interior of the closed 2-disk has no proper countable-index subgroups. The proof is an application of the…

Geometric Topology · Mathematics 2024-03-11 Nicholas G. Vlamis

We completely classify the locally finite, infinite graphs with pure mapping class groups admitting a coarsely bounded generating set. We also study algebraic properties of the pure mapping class group: We establish a semidirect product…

Group Theory · Mathematics 2025-08-06 George Domat , Hannah Hoganson , Sanghoon Kwak
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