Lagrangian mapping class groups from a group homological point of view

Takuya Sakasai

doi:10.2140/agt.2012.12.267

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arXiv · 0910.5262

Lagrangian mapping class groups from a group homological point of view

Takuya Sakasai

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Abstract

We focus on two kinds of infinite index subgroups of the mapping class group of a surface associated with a Lagrangian submodule of the first homology of a surface. These subgroups, called Lagrangian mapping class groups, are known to play important roles in the interaction between the mapping class group and finite-type invariants of 3-manifolds. In this paper, we discuss these groups from a group (co)homological point of view. The results include the determination of their abelianizations, lower bounds of the second homology and remarks on the (co)homology of higher degrees. As a by-product of this investigation, we determine the second homology of the mapping class group of a surface of genus 3.

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Takuya Sakasai. 2011-11-30. Lagrangian mapping class groups from a group homological point of view. https://doi.org/10.2140/agt.2012.12.267

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