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

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.

Mathematics Subject Classification ID

General low-dimensional topology (57Mxx)

This page was built for publication: Pure braids, a new subgroup of the mapping class group and finite type invariants

Report a bug (only for logged in users!)Click here to report a bug for this page (MaRDI item Q6500763)