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arXiv · 1012.1914

The complex of partial bases for F_n and finite generation of the Torelli subgroup of Aut(F_n)

Matthew B. Day·Andrew Putman
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Abstract

We study the complex of partial bases of a free group, which is an analogue for $\Aut(F_n)$ of the curve complex for the mapping class group. We prove that it is connected and simply connected, and we also prove that its quotient by the Torelli subgroup of $\Aut(F_n)$ is highly connected. Using these results, we give a new, topological proof of a theorem of Magnus that asserts that the Torelli subgroup of $\Aut(F_n)$ is finitely generated.

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Matthew B. Day, Andrew Putman. 2010-12-09. The complex of partial bases for F_n and finite generation of the Torelli subgroup of Aut(F_n). https://doi.org/10.1007/s10711-012-9765-6

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