Let $K/\mathbf{Q}$ be a number field with ring of integers $O_K$.
Is $O_K\cap K^\ast = O_K^\ast$?
I can't show that the inverse of an element in $O_K\cap K^\ast$ lies in $O_K^\ast$...
Let $K/\mathbf{Q}$ be a number field with ring of integers $O_K$.
Is $O_K\cap K^\ast = O_K^\ast$?
I can't show that the inverse of an element in $O_K\cap K^\ast$ lies in $O_K^\ast$...