Module

KummerEisenstein.lean

Nyll.ValuedFieldTheory.Valuation.DiscreteValuationField.KummerEisenstein
2 declarations indexed from sourceView source ↗

Eisenstein binomials from a prime parameter

A positive-power binomial X ^ n - C π is Eisenstein at the principal ideal of a prime element. In an integrally closed domain, its image in the fraction field is therefore irreducible. These inputs require no valuation, residue-field comparison, or prescribed extension degree.

Imports8
  • Mathlib.Algebra.GroupWithZero.Divisibility
  • Mathlib.Algebra.Polynomial.Coeff
  • Mathlib.Algebra.Polynomial.Degree.Operations
  • Mathlib.Algebra.Polynomial.Monic
  • Mathlib.RingTheory.Ideal.Operations
  • Mathlib.RingTheory.Ideal.Span
  • Mathlib.RingTheory.Polynomial.Eisenstein.Basic
  • Mathlib.RingTheory.Polynomial.GaussLemma
Imported by2

Declarations

ValuationTheory.DiscreteValuationField.X_pow_sub_C_isEisensteinAt_of_prime_parameter

A prime parameter makes a positive-power binomial Eisenstein.

Source context 5 commands

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

namespace ValuationTheory.DiscreteValuationField
open Polynomial
open scoped Polynomial
universe u v
variable {R : Type u} [CommRing R] [IsDomain R]
theorem X_pow_sub_C_isEisensteinAt_of_prime_parameter
    (π : R) (hπ : Prime π) (n : ℕ) (hn : 0 < n) :
    (X ^ n - C π).IsEisensteinAt (Ideal.span ({π} : Set R))
ValuationTheory.DiscreteValuationField.X_pow_sub_C_irreducible_of_prime_parameter

The Eisenstein binomial is irreducible over the fraction field.

Source context 5 commands

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

namespace ValuationTheory.DiscreteValuationField
open Polynomial
open scoped Polynomial
universe u v
variable {R : Type u} [CommRing R] [IsDomain R]
theorem X_pow_sub_C_irreducible_of_prime_parameter
    [IsIntegrallyClosed R]
    (K : Type v) [Field K] [Algebra R K] [IsFractionRing R K]
    (π : R) (hπ : Prime π) (n : ℕ) (hn : 0 < n) :
    Irreducible (X ^ n - C (algebraMap R K π))