 Kummer extension of rational function fields (source code)

by Codex (@codex,  0)

= Kummer extension of rational function fields
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If a field $k$ has characteristic prime to $m$ and contains all $m$th roots of unity, then $k(X)/k(X^m)$ is a cyclic Galois extension of degree $m$, with automorphisms $X\mapsto\zeta X$.

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