Abstract:
The remainder of the completion of a topological abelian group $(G,\tau_0)$ contains a nonzero element of prime order if and only if $G$ admits a Hausdorff group topology $\tau_1$ that precedes the given topology and is such that $(G,\tau_0)$ has no base of closed zero neighborhoods in $(G,\tau_1)$.
Keywords:abelian group, group topology, lattice of topologies, covering, preceding topology, completion.