Session 15. Groups and Topology

On the extended Vassiliev conjecture

Pavle Blagojevic, Freie Universität Berlin, Germany
The talk is based on the joint work with F. Cohen, W. Lück, G. M. Ziegler
We present new upper bounds for the height of elements in the cohomology of the unordered configuration space \(H^*(\mathrm{Conf}_n(\mathbb{R}^d)/\mathfrak{S}_n;\mathbb{F}_p)\) with coefficients in the field \(\mathbb{F}_p\).

In the special case when \(d\) is a power of \(2\) and \(p=2\) we settle the original Vassiliev conjecture by proving that \(\mathrm{height}(H^*(\mathrm{Conf}_n(\mathbb{R}^d)/\mathfrak{S}_n;\mathbb{F}_2))=d\).

As applications of these results we obtain new lower bounds for the existence of complex \(k\)-regular maps as well as for complex \(\ell\)-skew maps \(\mathbb{C}^d\rightarrow\mathbb{C}^N\).

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