Abstract:
Let $k$ be a nondyadic local number field and let $K=k(\sqrt\omega)$ be its unramifield quadratic extension. A complete description is suggested for the intermediate subgroups of the general linear group $\mathrm{G=GL}(2,k)$ of degree 2 over the field $k$ that contain the nonsplit maximal torus $T=T(\omega)$ (i.e., the image in $\mathrm G$ of the multiplicative group $K^*$ of the field $K$ under the regular embedding). In particular, the torus $T(\omega)$ is polynormal in $\mathrm{GL}(2,k)$. Bibliography: 11 titles.