Module

LevelFieldTower.lean

Nyll.ClassFieldTheory.LubinTate.FiniteLevel.LevelFieldTower
3 declarations indexed from sourceView source ↗

The tower of standard Lubin--Tate level fields

The primitive roots defining the standard finite levels are chosen independently in one separable closure. Exact torsion and normality show that the resulting simple fields nevertheless form an increasing tower.

Declarations

LubinTate.standardLubinTatePrimitivePredecessorInLevelField

The polynomial predecessor of the primitive level-n + 1 generator, regarded as an element of the level-n + 1 field itself.

Source context 6 commands

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

noncomputable section
open scoped Polynomial
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
def standardLubinTatePrimitivePredecessorInLevelField
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K))
    {m n : ℕ} (_hmn : m ≤ n) :
    standardLubinTateLevelField hπ n
LubinTate.standardLubinTatePrimitivePredecessorInLevelField_coe

Coercing the internal predecessor to the separable closure gives the ambient polynomial predecessor used by the exact-torsion theorem.

Source context 6 commands

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

noncomputable section
open scoped Polynomial
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
theorem standardLubinTatePrimitivePredecessorInLevelField_coe
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K))
    {m n : ℕ} (hmn : m ≤ n) :
    (standardLubinTatePrimitivePredecessorInLevelField hπ hmn :
        SeparableClosure K) =
      (standardLubinTatePolynomialIterateOverSeparableClosure
        F π (n - m)).eval
          (chosenStandardLubinTatePrimitiveRoot hπ n)
LubinTate.standardLubinTateLevelField_mono

The independently chosen standard Lubin--Tate level fields form an increasing tower inside the fixed separable closure.

Source context 6 commands

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

noncomputable section
open scoped Polynomial
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
theorem standardLubinTateLevelField_mono
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K))
    {m n : ℕ} (hmn : m ≤ n) :
    standardLubinTateLevelField hπ m ≤
      standardLubinTateLevelField hπ n