Hereditarily minimal topological groups
A Hausdorff topological group $(G, \tau)$ is called minimal if there exists no Hausdorff group topology on $G$ which is strictly coarser than $\tau$.
We say that a topological group $G$ is hereditarily minimal, if every subgroup of $G$ is minimal.
By Prodanov's Theorem an infinite compact abelian group $K$ is isomorphic to $\Z_p$ (p-adic integers) for some prime $p$ if and only if $K$ is hereditarily minimal.
We study hereditarily minimal groups. The following theorem is one of our main results.
Let $G$ be an infinite hereditarily minimal locally compact group that is either compact or locally solvable. Then $G$ is either center-free or isomorphic to $\Z_p$, for some prime $p$.
If $G$ is an infinite hereditarily minimal locally compact nilpotent group, then $G$ is isomorphic to $\Z_p$ for some prime $p$.
This is a joint work with D. Dikranjan, D. Toller and W. Xi.