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9 votes
1 answer
605 views

Mapping Class Groups and torus (JSJ) decomposition of closed 3-manifolds

I am wondering if some intuitive relation exists between Mapping Class Group (MCG) of a 3-manifold (assume "simple" enough manifolds: closed,compact,irreducible, orientable, non-hyperbolic) and its ...
SKShukla's user avatar
  • 231
6 votes
1 answer
1k views

Dehn-Nielsen-Baer Theorem for surfaces with boundary and punctures

Let $S=S_{g,b}$ be a compact orientable surface with genus $g$ and $b$ boundary components, such that $\chi(S)=2-2g-b<0$. Let $Q=\{x_1,\ldots , x_n\}$ be a set of $n$ distinguished points in the ...
Mark Grant's user avatar
  • 35.9k
5 votes
1 answer
333 views

Proof of homotopic essential simple close curves are isotopic

In the book by Benson Farb and Dan Margalit A primer on mapping class groups, Princeton Mathematical Series 49. Princeton, NJ: Princeton University Press (ISBN 978-0-691-14794-9/hbk; 978-1-400-83904-9/...
T566y65tt's user avatar
  • 119
3 votes
3 answers
769 views

Reducible 3d torus bundles

Here reducible means that the mapping class for the fiber is a reducible auto-homeomorph in the sense of Nielsen-Thruston. So, could anyone give me a hint to classify them? In contrast, do you agree ...
janmarqz's user avatar
  • 345
3 votes
1 answer
552 views

Is the Action of the mapping class group transitive on embedded arcs?

Let S be a surface of genus g with some parked points (n of them). Assume $n \geq 2$ and fix two of the marked points. Consider the set of embedded arcs going between these two special points. The ...
Chris Schommer-Pries's user avatar
3 votes
1 answer
909 views

Isomorphism between a mapping class group and the fundamental group of a moduli space

For some fixed integer $d \geq 3$, let $M(0, d)$ be the mapping class group of self-homeomorphisms of the Riemann sphere which fix each of the $d$ points $0, 1, ... , d-2, \infty$. Let $X$ be the ...
Jeff Yelton's user avatar
  • 1,298