Module

MaximalRealProPOutside.lean

Nyll.SawinTotallyRealTowers.MaximalRealProPOutside
5 declarations indexed from sourceView source ↗

The maximal real compositum with prescribed ramification support

The field is formed from the concrete directed family of finite layers. Galoisness and total reality follow from the corresponding properties of those layers. The pro-p property and arithmetic rank estimates are separate theorems, not inputs to this construction.

Declarations

ClassFieldTower.Sawin.maximalRealProPOutside

The compositum of all admissible finite real p-extensions of ℚ inside its fixed algebraic closure.

Source context 4 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace ClassFieldTower.Sawin
def maximalRealProPOutside (p : ℕ) (T : Set (HeightOneSpectrum (𝓞 ℚ))) :
    IntermediateField ℚ (AlgebraicClosure ℚ)
ClassFieldTower.Sawin.le_maximalRealProPOutside

Every admissible finite layer is contained in the maximal compositum.

Source context 4 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace ClassFieldTower.Sawin
theorem le_maximalRealProPOutside {p : ℕ}
    {T : Set (HeightOneSpectrum (𝓞 ℚ))}
    (E : FiniteRealPExtension p T) :
    E.val.toIntermediateField ≤ maximalRealProPOutside p T
ClassFieldTower.Sawin.maximalRealProPOutside_isGalois

The constructed maximal compositum is Galois over ℚ.

Source context 4 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace ClassFieldTower.Sawin
theorem maximalRealProPOutside_isGalois (p : ℕ)
    (T : Set (HeightOneSpectrum (𝓞 ℚ))) :
    IsGalois ℚ (maximalRealProPOutside p T)
ClassFieldTower.Sawin.maximalRealProPOutside_isTotallyReal

Total reality is preserved by the full, possibly infinite compositum.

Source context 4 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace ClassFieldTower.Sawin
theorem maximalRealProPOutside_isTotallyReal (p : ℕ)
    (T : Set (HeightOneSpectrum (𝓞 ℚ))) :
    IsTotallyReal (maximalRealProPOutside p T)
ClassFieldTower.Sawin.isAdmissibleFiniteLayer_iff_le_maximalRealProPOutside

A finite Galois intermediate field lies in the maximal compositum exactly when it satisfies the original arithmetic conditions. Directed finite support and descent rule out additional inadmissible finite layers.

Source context 4 commands

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

open scoped NumberField
open NumberField IsDedekindDomain
noncomputable section
namespace ClassFieldTower.Sawin
theorem isAdmissibleFiniteLayer_iff_le_maximalRealProPOutside
    (p : ℕ) (T : Set (HeightOneSpectrum (𝓞 ℚ)))
    (E : FiniteGaloisIntermediateField ℚ (AlgebraicClosure ℚ)) :
    IsAdmissibleFiniteLayer p T E ↔
      E.toIntermediateField ≤ maximalRealProPOutside p T