Module

NormSubgroup.lean

Nyll.ClassFieldTheory.LubinTate.FiniteLevel.NormSubgroup
7 declarations indexed from sourceView source ↗

The norm subgroup of a standard Lubin--Tate level

This file introduces the local norm subgroup attached to a standard finite Lubin--Tate level. The norm identity for the negative primitive generator shows that the chosen base uniformizer is an actual norm. Consequently its entire cyclic subgroup of integral powers lies in the norm subgroup.

The higher-principal-unit contribution is intentionally left to the later norm calculation.

Declarations

LubinTate.standardLubinTateNormSubgroup

The local norm subgroup attached to a standard finite Lubin--Tate level.

Source context 5 commands

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

noncomputable section
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
def standardLubinTateNormSubgroup
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K))
    (n : ℕ) : Subgroup Kˣ
LubinTate.standardLubinTateBaseUniformizerUnit

The chosen base uniformizer, regarded as a nonzero field unit.

Source context 5 commands

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

noncomputable section
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
def standardLubinTateBaseUniformizerUnit
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K)) :
    Kˣ
LubinTate.standardLubinTateBaseUniformizerUnit_coe

The chosen uniformizer unit has the expected underlying field element.

Source context 5 commands

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

noncomputable section
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
theorem standardLubinTateBaseUniformizerUnit_coe
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K)) :
    (standardLubinTateBaseUniformizerUnit hπ : K) = (π : K)
LubinTate.standardLubinTateBaseUniformizerUnit_mem_normSubgroup

The chosen base uniformizer is an actual norm from every standard finite level.

Source context 5 commands

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

noncomputable section
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
theorem standardLubinTateBaseUniformizerUnit_mem_normSubgroup
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K))
    (n : ℕ) :
    standardLubinTateBaseUniformizerUnit hπ ∈
      standardLubinTateNormSubgroup hπ n
LubinTate.standardLubinTateBaseUniformizerUnit_inv_mem_normSubgroup

The inverse uniformizer is also a norm, for conventions that choose the inverse generator of the valuation factor.

Source context 5 commands

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

noncomputable section
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
theorem standardLubinTateBaseUniformizerUnit_inv_mem_normSubgroup
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K))
    (n : ℕ) :
    (standardLubinTateBaseUniformizerUnit hπ)⁻¹ ∈
      standardLubinTateNormSubgroup hπ n
LubinTate.standardLubinTateBaseUniformizerUnit_zpowers_le_normSubgroup

Every integral power of the chosen base uniformizer is a norm.

Source context 5 commands

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

noncomputable section
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
theorem standardLubinTateBaseUniformizerUnit_zpowers_le_normSubgroup
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K))
    (n : ℕ) :
    Subgroup.zpowers (standardLubinTateBaseUniformizerUnit hπ) ≤
      standardLubinTateNormSubgroup hπ n
LubinTate.standardLubinTateBaseUniformizerUnit_inv_zpowers_le_normSubgroup

The same cyclic norm-subgroup inclusion using the inverse-uniformizer convention.

Source context 5 commands

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

noncomputable section
universe u v
namespace LubinTate
open LocalFieldTheory.DiscreteValuationField
variable {K : Type u} [Field K]
theorem standardLubinTateBaseUniformizerUnit_inv_zpowers_le_normSubgroup
    {F : LocalField.{u, v} K} {π : F.valuationSubring}
    (hπ : F.toCompleteDVF.valuation.IsUniformizer (π : K))
    (n : ℕ) :
    Subgroup.zpowers ((standardLubinTateBaseUniformizerUnit hπ)⁻¹) ≤
      standardLubinTateNormSubgroup hπ n