The Clifford-cyclotomic group and Euler-Poincaré characteristics

Colin J. Ingalls, Bruce W. Jordan, Allan Keeton +2

For an integer $n\ge 8$ divisible by $4$, let $R_n=\mathbb{Z}[{\zeta }_n,1/2]$ and let $U_2(R_n)$ be the group of $2\times 2$ unitary matrices with entries in $R_n$. Set $…