Suppose $G$ is a multiplicatively written abelian $p$-group, where $p$ is a prime, and $F$ is a field of arbitrary characteristic. The main results in this paper are that none of the Sylow $p$-group of all normalized units $S(FG)$ in the group ring $FG$ and its quotient group $S(FG)/G$ cannot be Prufer groups. This contrasts a classical conjecture for which $S(FG)/G$ is a direct factor of a direct sum of generalized Prufer groups whenever $F$ is a perfect field of characteristic $p$.
Abstract
We compare the Kummer flat (resp., Kummer étale) cohomology with the flat (resp., étale) cohomology with coefficients in smooth commutative group schemes, finite flat group schemes, and Kato’s logarithmic multiplicative group. We are particularly interested in the case of algebraic tori in the Kummer flat topology. We also make some computations for certain special cases of the base log scheme.