Module

PadicValuationInertia.lean

Nyll.ClassFieldTheory.RamificationTheory.HilbertRamification.Dedekind.PadicValuationInertia
31 declarations indexed from sourceView source ↗

The global valuation/prime-ideal bridge in the global cyclotomic inertia argument

An extension w of the rational p-adic absolute value determines a valuation subring of a number field M. This file synchronizes that valuation subring with a concrete prime ideal of 𝓞 M, proves that the prime lies over (p), and identifies the valuation subring with the localization of 𝓞 M at that prime.

The final comparison sends ideal-theoretic inertia injectively to the valuation-subring inertia group. Thus the local cardinality bound furnished by the localization and decomposition comparison applies to the chosen global prime without an extra compatibility hypothesis.

Comparison of ideal inertia with valuation inertia

Declarations

HilbertRamification.Dedekind.dedekindAtPrimeValuationSubring

The localization of a Dedekind domain at a nonzero prime, realized inside its fraction field as a valuation subring. This construction belongs to the ideal/localization bridge; it is kept private here until that bridge is factored into prime-decomposition theory.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
def dedekindAtPrimeValuationSubring
    (B : Type*) [CommRing B] [IsDedekindDomain B]
    {L : Type*} [Field L] [Algebra B L] [IsFractionRing B L]
    (P : Ideal B) [P.IsPrime] (hP : P ≠ ⊥) :
    _root_.ValuationSubring L
HilbertRamification.Dedekind.dedekindAtPrimeValuationSubringAlgebra

The valuation-subring realization of a Dedekind localization carries its canonical algebra structure over the original domain.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
instance dedekindAtPrimeValuationSubringAlgebra
    (B : Type*) [CommRing B] [IsDedekindDomain B]
    {L : Type*} [Field L] [Algebra B L] [IsFractionRing B L]
    (P : Ideal B) [P.IsPrime] (hP : P ≠ ⊥) :
    Algebra B (dedekindAtPrimeValuationSubring B (L := L) P hP)
HilbertRamification.Dedekind.dedekindAtPrimeValuationSubringIsLocalization

The valuation-subring realization is the localization away from the chosen prime.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
instance dedekindAtPrimeValuationSubringIsLocalization
    (B : Type*) [CommRing B] [IsDedekindDomain B]
    {L : Type*} [Field L] [Algebra B L] [IsFractionRing B L]
    (P : Ideal B) [P.IsPrime] (hP : P ≠ ⊥) :
    IsLocalization P.primeCompl
      (dedekindAtPrimeValuationSubring B (L := L) P hP)
HilbertRamification.Dedekind.dedekindAtPrimeValuationSubringIsDedekindDomain

A Dedekind localization realized as a valuation subring is again a Dedekind domain.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
instance dedekindAtPrimeValuationSubringIsDedekindDomain
    (B : Type*) [CommRing B] [IsDedekindDomain B]
    {L : Type*} [Field L] [Algebra B L] [IsFractionRing B L]
    (P : Ideal B) [P.IsPrime] (hP : P ≠ ⊥) :
    IsDedekindDomain
      (dedekindAtPrimeValuationSubring B (L := L) P hP)
HilbertRamification.Dedekind.dedekindAtPrimeValuationSubringKrullDimLE

The valuation-subring realization of a nonzero Dedekind localization has Krull dimension at most one.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
instance dedekindAtPrimeValuationSubringKrullDimLE
    (B : Type*) [CommRing B] [IsDedekindDomain B]
    {L : Type*} [Field L] [Algebra B L] [IsFractionRing B L]
    (P : Ideal B) [P.IsPrime] (hP : P ≠ ⊥) :
    Ring.KrullDimLE 1
      (dedekindAtPrimeValuationSubring B (L := L) P hP)
HilbertRamification.Dedekind.globalPadicExtensionValuationSubring

The nonarchimedean extension valuation ring attached to a global extension of the rational p-adic absolute value.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
abbrev globalPadicExtensionValuationSubring
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    _root_.ValuationSubring M
HilbertRamification.Dedekind.ringOfIntegers_mem_globalPadicExtensionValuationSubring

Every algebraic integer belongs to the valuation ring defined by w. This is the integrally-closed valuation-ring argument, rather than an additional boundedness assumption on algebraic integers.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem ringOfIntegers_mem_globalPadicExtensionValuationSubring
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M)
    (x : 𝓞 M) :
    (x : M) ∈ globalPadicExtensionValuationSubring p M w
HilbertRamification.Dedekind.globalPadicRingOfIntegersToExtensionValuationSubring

The canonical inclusion 𝓞 M → A_w.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
def globalPadicRingOfIntegersToExtensionValuationSubring
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    𝓞 M →+* globalPadicExtensionValuationSubring p M w
HilbertRamification.Dedekind.globalPadicRingOfIntegersToExtensionValuationSubring_coe

The canonical map from 𝓞 M to the extension valuation ring agrees with the usual inclusion into M.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicRingOfIntegersToExtensionValuationSubring_coe
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M)
    (x : 𝓞 M) :
    ((globalPadicRingOfIntegersToExtensionValuationSubring p M w x :
        globalPadicExtensionValuationSubring p M w) : M) = (x : M)
HilbertRamification.Dedekind.globalPadicPrimeIdeal

The prime ideal of 𝓞 M which is the center of w.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
def globalPadicPrimeIdeal
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    Ideal (𝓞 M)
HilbertRamification.Dedekind.mem_globalPadicPrimeIdeal_iff

Membership in the synchronized prime is the strict w-adic inequality.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem mem_globalPadicPrimeIdeal_iff
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M)
    (x : 𝓞 M) :
    x ∈ globalPadicPrimeIdeal p M w ↔ w.1 (x : M) < 1
HilbertRamification.Dedekind.globalPadicPrimeIdeal_isPrime

The center of a valuation ring is prime.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicPrimeIdeal_isPrime
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    (globalPadicPrimeIdeal p M w).IsPrime
HilbertRamification.Dedekind.int_mem_globalPadicPrimeIdeal_under_iff

On rational integers, membership in the center is divisibility by p.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem int_mem_globalPadicPrimeIdeal_under_iff
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M)
    (z : ℤ) :
    algebraMap ℤ (𝓞 M) z ∈ globalPadicPrimeIdeal p M w ↔
      (p : ℤ) ∣ z
HilbertRamification.Dedekind.globalPadicPrimeIdeal_under_eq_span

The contraction of the synchronized prime to ℤ is the usual principal ideal (p).

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicPrimeIdeal_under_eq_span
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    (globalPadicPrimeIdeal p M w).under ℤ =
      Ideal.span ({(p : ℤ)} : Set ℤ)
HilbertRamification.Dedekind.globalPadicPrimeIdeal_liesOver

The synchronized prime lies over the rational height-one prime p.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicPrimeIdeal_liesOver
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    (globalPadicPrimeIdeal p M w).LiesOver
      (rationalPrimeIdeal (⟨p, Fact.out⟩ : Nat.Primes))
HilbertRamification.Dedekind.globalPadicPrimeIdeal_ne_bot

The synchronized prime is nonzero.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicPrimeIdeal_ne_bot
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    globalPadicPrimeIdeal p M w ≠ ⊥
HilbertRamification.Dedekind.globalPadicPrimeIdeal_isMaximal

In the Dedekind ring 𝓞 M, the synchronized nonzero prime is maximal.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicPrimeIdeal_isMaximal
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    (globalPadicPrimeIdeal p M w).IsMaximal
HilbertRamification.Dedekind.instIsPrimeGlobalPadicPrimeIdeal

The center of a global p-adic place is a prime ideal.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
instance instIsPrimeGlobalPadicPrimeIdeal
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    (globalPadicPrimeIdeal p M w).IsPrime
HilbertRamification.Dedekind.instIsMaximalGlobalPadicPrimeIdeal

The center of a global p-adic place is a maximal ideal.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
instance instIsMaximalGlobalPadicPrimeIdeal
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    (globalPadicPrimeIdeal p M w).IsMaximal
HilbertRamification.Dedekind.instLiesOverGlobalPadicPrimeIdeal

The center of a global p-adic place lies over the rational prime ideal generated by p.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
instance instLiesOverGlobalPadicPrimeIdeal
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    (globalPadicPrimeIdeal p M w).LiesOver
      (rationalPrimeIdeal ⟨p, Fact.out⟩)
HilbertRamification.Dedekind.globalPadicPrimeHeightOneSpectrum

The height-one prime of 𝓞 M centered at w.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
def globalPadicPrimeHeightOneSpectrum
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    IsDedekindDomain.HeightOneSpectrum (𝓞 M)
HilbertRamification.Dedekind.globalPadicPrimeLocalizationValuationSubring

The ordinary localization of 𝓞 M at the prime centered at w, viewed as a valuation subring of M.

Source context 8 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
abbrev globalPadicPrimeLocalizationValuationSubring
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    _root_.ValuationSubring M
HilbertRamification.Dedekind.globalPadicPrime_localizationValuationSubring_eq

The valuation ring defined by the absolute value w is exactly the ordinary localization of 𝓞 M at its center.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicPrime_localizationValuationSubring_eq
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    globalPadicPrimeLocalizationValuationSubring p M w =
      globalPadicExtensionValuationSubring p M w
HilbertRamification.Dedekind.globalPadicPrimeCompl_smul_of_mem_inertia
Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicPrimeCompl_smul_of_mem_inertia
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M)
    (sigma : HilbertRamification.Dedekind.inertiaGroup
      (globalPadicPrimeIdeal p M w) (M ≃ₐ[ℚ] M))
    {s : 𝓞 M}
    (hs : s ∈ (globalPadicPrimeIdeal p M w).primeCompl) :
    (sigma : M ≃ₐ[ℚ] M) • s ∈
      (globalPadicPrimeIdeal p M w).primeCompl
HilbertRamification.Dedekind.globalPadicIdealInertia_maps_localization

An ideal-inertia automorphism preserves the localization of 𝓞 M at the synchronized prime.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicIdealInertia_maps_localization
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M)
    (sigma : HilbertRamification.Dedekind.inertiaGroup
      (globalPadicPrimeIdeal p M w) (M ≃ₐ[ℚ] M))
    {x : M}
    (hx : x ∈
      globalPadicPrimeLocalizationValuationSubring p M w) :
    (sigma : M ≃ₐ[ℚ] M) x ∈
      globalPadicPrimeLocalizationValuationSubring p M w
HilbertRamification.Dedekind.globalPadicIdealInertiaToLocalizationDecomposition

Ideal inertia at the synchronized prime maps to the decomposition group of its localization.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
def globalPadicIdealInertiaToLocalizationDecomposition
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    HilbertRamification.Dedekind.inertiaGroup
        (globalPadicPrimeIdeal p M w) (M ≃ₐ[ℚ] M) →
      RamificationTheory.HilbertRamification.ValuationSubring.decompositionGroup ℚ
        (globalPadicPrimeLocalizationValuationSubring p M w)
HilbertRamification.Dedekind.globalPadicIdealInertiaToLocalizationDecomposition_mem_maximalIdealInertia
Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem
    globalPadicIdealInertiaToLocalizationDecomposition_mem_maximalIdealInertia
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M)
    (sigma : HilbertRamification.Dedekind.inertiaGroup
      (globalPadicPrimeIdeal p M w) (M ≃ₐ[ℚ] M)) :
    globalPadicIdealInertiaToLocalizationDecomposition p M w sigma ∈
      (IsLocalRing.maximalIdeal
        (globalPadicPrimeLocalizationValuationSubring p M w)).toAddSubgroup.inertia
        (RamificationTheory.HilbertRamification.ValuationSubring.decompositionGroup ℚ
          (globalPadicPrimeLocalizationValuationSubring p M w))
HilbertRamification.Dedekind.globalPadicIdealInertiaToLocalizationDecomposition_mem_inertia
Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem
    globalPadicIdealInertiaToLocalizationDecomposition_mem_inertia
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M)
    (sigma : HilbertRamification.Dedekind.inertiaGroup
      (globalPadicPrimeIdeal p M w) (M ≃ₐ[ℚ] M)) :
    globalPadicIdealInertiaToLocalizationDecomposition p M w sigma ∈
      RamificationTheory.HilbertRamification.ValuationSubring.inertiaGroup ℚ
        (globalPadicPrimeLocalizationValuationSubring p M w)
HilbertRamification.Dedekind.globalPadicIdealInertiaToLocalizationInertia

The canonical localization map from global ideal inertia to valuation inertia.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
def globalPadicIdealInertiaToLocalizationInertia
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    HilbertRamification.Dedekind.inertiaGroup
        (globalPadicPrimeIdeal p M w) (M ≃ₐ[ℚ] M) →*
      RamificationTheory.HilbertRamification.ValuationSubring.inertiaGroup ℚ
        (globalPadicPrimeLocalizationValuationSubring p M w) where
  toFun sigma :=
    ⟨globalPadicIdealInertiaToLocalizationDecomposition p M w sigma,
      globalPadicIdealInertiaToLocalizationDecomposition_mem_inertia
        p M w sigma⟩
  map_one' := by
    apply Subtype.ext
    apply Subtype.ext
    rfl
  map_mul' _ _ := by
    apply Subtype.ext
    apply Subtype.ext
    rfl
HilbertRamification.Dedekind.globalPadicIdealInertiaToLocalizationInertia_injective

The localization map is injective because it does not change the underlying ℚ-automorphism of M.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicIdealInertiaToLocalizationInertia_injective
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    Function.Injective
      (globalPadicIdealInertiaToLocalizationInertia p M w)
HilbertRamification.Dedekind.globalPadicPrimeIdeal_inertia_natCard_le_valuationInertia

The exact cardinal comparison needed in the global cyclotomic inertia argument: the ideal inertia group at the synchronized prime is no larger than the localization and decomposition comparison valuation inertia group attached to w.

Source context 9 commands

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

noncomputable section
namespace HilbertRamification.Dedekind
open NumberField
open AlgebraicNumberTheory.Valuations
open AlgebraicNumberTheory.Ramification
open scoped NumberField
variable (p : ℕ) [Fact p.Prime]
variable (M : Type) [Field M] [NumberField M] [IsAbelianGalois ℚ M]
omit [IsAbelianGalois ℚ M] in
theorem globalPadicPrimeIdeal_inertia_natCard_le_valuationInertia
    (w : AbsoluteValueExtension (Rat.AbsoluteValue.padic p) M) :
    Nat.card
        (HilbertRamification.Dedekind.inertiaGroup
          (globalPadicPrimeIdeal p M w) (M ≃ₐ[ℚ] M)) ≤
      Nat.card
        (RamificationTheory.HilbertRamification.ValuationSubring.inertiaGroup ℚ
          (globalPadicExtensionValuationSubring p M w))