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Theorems · Theorem · field theory

Algebra.IsUnramifiedAt.not_minpoly_sq_dvd

∀ {K : Type u_1} {A : Type u_2} [inst : Field K] [inst_1 : CommRing A] [inst_2 : Algebra K A] (Q : Ideal A)
  [inst_3 : Q.IsPrime] [Algebra.IsUnramifiedAt K Q] (x : A) (p : Polynomial K),
  Ideal.span {p} = RingHom.ker (Polynomial.aeval x).toRingHom →
    Function.Surjective ⇑(Polynomial.aeval x) → ¬minpoly K ((algebraMap A Q.ResidueField) x) ^ 2 ∣ p

If A = K[X]/⟨p⟩ is unramified at some prime Q, then the minpoly of X in κ(Q) only divides p once.

Defined in
Mathlib.RingTheory.Unramified.Field
Cited by
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Foundations
Depth 181 from the axioms · uses propext, Classical.choice, Quot.sound
Assumes
FieldCommRingAlgebraIdeal.IsPrimeAlgebra.IsUnramifiedAt

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