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Bordism Invariants of the Mapping Class Group

Aaron Heap
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Abstract

We define new bordism and spin bordism invariants of certain subgroups of the mapping class group of a surface. In particular, they are invariants of the Johnson filtration of the mapping class group. The second and third terms of this filtration are the well-known Torelli group and Johnson subgroup, respectively. We introduce a new representation in terms of spin bordism, and we prove that this single representation contains all of the information given by the Johnson homomorphism, the Birman-Craggs homomorphism, and the Morita homomorphism.

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Aaron Heap. 2005-02-28. Bordism Invariants of the Mapping Class Group. https://arxiv.org/abs/math/0502587

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