Module

KummerAlgebraFiniteFree.lean

Nyll.ClassFieldTheory.Theorems.HilbertSymbols.KummerAlgebraFiniteFree
1 declaration indexed from sourceView source ↗

Finite freeness of a Kummer algebra

The polynomial X ^ n - a is monic for positive n. Its quotient algebra is finite free even when that polynomial is reducible, so no field assumption is placed on the Kummer algebra.

Declarations

ClassFieldTheory.kummerAlgebra_finiteFree

A Kummer algebra is finite free over its base field, including reducible and degree-one cases.

Source context 2 commands

Surrounding namespaces, section variables, and local commands at this declaration.

namespace ClassFieldTheory
universe u
theorem kummerAlgebra_finiteFree
    (K : Type u) [Field K] (n : ℕ+) (a : Kˣ) :
    Module.Finite K (KummerAlgebra K n a) ∧
      Module.Free K (KummerAlgebra K n a)