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Revision difference : abelian number field
Version current Version 1
\begin{defn} \begin{defn}
An abelian number field is a number field $K$ such that $K/\Rats$ is an abelian extension, i.e. $K/\Rats$ is Galois and $\Gal(K/\Rats)$ is an abelian group. An abelian number field is a number field $K$ such that $K/\Rats$ is an abelian extension, i.e. $K/\Rats$ is Galois and $\Gal(K/\Rats)$ is an abelian group.
\end{defn} \end{defn}
The abelian number fields are classified by the Kronecker-Weber Theorem. The abelian number fields are classified by the Kronecker-Weber Theorem.
\begin{defn}
A cyclic number field is an (abelian) number field $K$ such that $K/\Rats$ is a Galois extension and $\Gal(K/\Rats)$ is a finite cyclic group (therefore abelian).
\end{defn}