For an unramified lift `Φ`, the extended ideal `𝔪 O[X]/(Φ)` is maximal, units can be detected modulo it, and `O[X]/(Φ)` is local with that maximal ideal.
ProvedTypeDensity.base_ideal_maximal_localtype-density
For an unramified lift Φ, the extended ideal 𝔪 O[X]/(Φ) is maximal, units can be detected modulo it, and O[X]/(Φ) is local with that maximal ideal.
Preamble
import Definitions.Def_TypeDensity_Basic import Definitions.Def_TypeDensity_Formula_LawAlgebra import Definitions.Def_TypeDensity_Algebra_AlgebraType import Definitions.Def_TypeDensity_Measure_AdicCylinders import Definitions.Def_TypeDensity_Measure_HenselProducts import Definitions.Def_TypeDensity_Unramified_Extension import Definitions.Def_TypeDensity_Measure_PrimitiveLocus import Definitions.Def_TypeDensity_Algebra_FactorInvariant import Theorems.Thm_TypeDensity_unramified_adic_complete import Theorems.Thm_TypeDensity_residue_extension_field import Mathlib.FieldTheory.RatFunc.Basic import Mathlib.MeasureTheory.Measure.Haar.Unique import Mathlib.NumberTheory.ArithmeticFunction.Moebius import Mathlib.NumberTheory.Padics.PadicIntegers import Mathlib.RingTheory.IntegralClosure.IntegralRestrict import Mathlib.RingTheory.MvPowerSeries.Basic import Mathlib.RingTheory.RamificationInertia.Basic import Mathlib.Topology.Algebra.Nonarchimedean.AdicTopology import Mathlib.FieldTheory.Finite.GaloisField import Mathlib.RingTheory.AdicCompletion.Algebra import Mathlib.RingTheory.RegularLocalRing.Defs import Mathlib.RingTheory.Henselian import Mathlib.Topology.Algebra.MvPolynomial import Mathlib.Algebra.Group.Pi.Units import Mathlib.Order.CompletePartialOrder import Mathlib.RingTheory.Polynomial.Resultant.Basic import Mathlib.RingTheory.SimpleRing.Principal import Mathlib.Algebra.GroupWithZero.Submonoid.CancelMulZero import Mathlib.Algebra.Module.StablyFree.Basic import Mathlib.NumberTheory.Padics.RingHoms set_option autoImplicit false open TypeDensity open scoped BigOperators ENNReal
Formal statement
theorem TypeDensity.base_ideal_maximal_local (O : Type) [CommRing O] [IsLocalRing O]
[IsAdicComplete (IsLocalRing.maximalIdeal O) O] [Finite (IsLocalRing.ResidueField O)]
(Φ : Polynomial O) (hΦ : IsUnramifiedLift O Φ) :
(baseIdeal O Φ).IsMaximal ∧ (∀ x : AdjoinRoot Φ, IsUnit (baseReduce O Φ x) → IsUnit x) ∧
∃ _ : IsLocalRing (AdjoinRoot Φ),
IsLocalRing.maximalIdeal (AdjoinRoot Φ) = baseIdeal O Φ := by sorrySource
TypeDensity/Unramified/FrobeniusDescent.lean#L312-L337