January 31st, 2008

Kai-Uwe Bux (UVa)

Title: The dimension of the group of partially symmetric automorphisms of a free group

Abstract: (Joint with Ruth Charney and Karen Vogtmann) We determine the virtual dimension of the group $P\Sigma(n,k)\subset Out(F_n)$ generated by automorphisms which send the first $k$ generators to conjugates of themselves (each x_i is going to a conjugate $wx_iw^{-1}$). Thm: $vcd(P\Sigma(n,k))=2n-k-2$.