Maximal unramified extension
= Maximal unramified extension
{title2=$K^{\mathrm{nr}}$}
The maximal unramified extension $K^{\mathrm{nr}}$ is the union of all finite unramified extensions of a non-Archimedean local field $K$. Its Galois group is canonically $\widehat{\mathbb Z}$, generated topologically by <Frobenius>.