Tuesday Seminar on Topology

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Date, time & place Tuesday 17:00 - 18:30 056Room #056 (Graduate School of Math. Sci. Bldg.)
Organizer(s) KAWAZUMI Nariya, KITAYAMA Takahiro, SAKASAI Takuya

2012/10/23

16:30-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Nariya Kawazumi (The University of Tokyo)
A geometric approach to the Johnson homomorphisms (JAPANESE)
[ Abstract ]
We re-construct the Johnson homomorphisms as an embeddig of the Torelli
group
into the completed Goldman-Turaev Lie bialgebra. Then the image is
included in the
kernel of the Turaev cobracket. In the case where the boundary is
connected,
the Turaev cobracket clarifies a geometric meaning of the Morita traces.
Time permitting, we also discuss the case of holed discs.
This talk is based on a joint work with Yusuke Kuno (Tsuda College).