On characteristic classes of exotic manifold bundles

Date:
11.01.2018

Speaker:
Manuel Krannich

Time:
15:45 h

Abstract: Restricting diffeomorphisms of a closed nmanifold M to an embedded disc D^n induces a fibration sequence Diff(M,D^n) > Diff(M) > Emb(D^n,M), where Emb(D^n,M) is the space of embeddings of the disc and Diff(M,D^n) is the group of diffeomorphisms fixing it. Connect summing M with an exotic sphere S does not affect the homotopy type of the two outer terms in the sequence, so one might expect it to be hard to detect the possible exotic nature of M#S by means of homotopical properties of its group of diffeomorphisms. Combining recent advances in manifold theory by Galatius and RandalWilliams with computations in stable homotopy theory, I will present results on the behavior of the cohomology of BDiff(M) when taking the connected sum with an exotic sphere.

Place:
SR 2.058 (20.30)