The Second Johnson Homomorphism and the Second Rational Cohomology of the Johnson Kernel
نویسنده
چکیده
The Johnson kernel is the subgroup of the mapping class group of a surface generated by Dehn twists along bounding simple closed curves, and has the second Johnson homomorphism as a free abelian quotient. We will determine the kernel of the map induced on the second rational cohomology by the second Johnson homomorphism in terms of the representation theory of the symplectic group.
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