Pure braids, a new subgroup of the mapping class group and finite type invariants

Jerome Levine

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arXiv · math/9712221

Pure braids, a new subgroup of the mapping class group and finite type invariants

Jerome Levine

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Abstract

In the study of the relation between the mapping class group M of a surface and the theory of finite-type invariants of homology 3-spheres, three subgroups of the mapping class group play a large role. They are the Torelli group, the Johnson subgroup K and a new subgroup L, which contains K, defined by a choice of a Lagrangian subgroup of the homology of the surface. In this work we determine the quotient L/K, in terms of the precise description of M/K given by Johnson and Morita. We also study the lower central series of L and K, using some natural imbeddings of the pure braid group in L and the theory of finite-type invariants.

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BibTeX RIS

Jerome Levine. 1997-12-03. Pure braids, a new subgroup of the mapping class group and finite type invariants. https://arxiv.org/abs/math/9712221

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