Module

FiniteIdealCanonicalTameExactness.lean

Nyll.EtaleFundamentalGroups.Inertia.FiniteIdealCanonicalTameExactness
2 declarations indexed from sourceView source ↗

Kernel and surjectivity of normalized finite characters

Proves that normalization preserves the finite principal-unit kernel and that the canonical character surjects onto its full root group.

Declarations

EtaleFundamentalGroups.Inertia.finiteIdealCanonicalTameCharacterGroupMap_ker

Actual exponential-characteristic normalization preserves the original finite principal-unit kernel. The required power is supplied by the actual finite arithmetic endpoint, independently of this group calculation.

Source context 6 commands

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

open scoped Pointwise
namespace EtaleFundamentalGroups.Inertia
open RamificationTheory.HilbertRamification.DiscreteValuationRing
universe u v
variable (A : Type u) (B : Type v) [CommRing A] [CommRing B] [IsDedekindDomain B]
  [Algebra A B] (G : Type v) [Group G] [Finite G] [MulSemiringAction G B]
  (Q : Ideal B) [Q.IsPrime] (hQ : Q ≠ ⊥)
  (p : ℕ) [ExpChar (IsLocalRing.ResidueField (Localization.AtPrime Q)) p]
  (hq : ∃ a : ℕ, finiteIdealNormalizationExponent A B G Q hQ = p ^ a)
include p hq
theorem finiteIdealCanonicalTameCharacterGroupMap_ker :
    (finiteIdealCanonicalTameCharacterGroupMap A B G Q hQ).ker =
      finiteIdealWildSubgroup B G Q hQ
EtaleFundamentalGroups.Inertia.finiteIdealCanonicalTameCharacterGroupMap_surjective

The actual normalized finite character maps onto the full root group.

Source context 6 commands

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

open scoped Pointwise
namespace EtaleFundamentalGroups.Inertia
open RamificationTheory.HilbertRamification.DiscreteValuationRing
universe u v
variable (A : Type u) (B : Type v) [CommRing A] [CommRing B] [IsDedekindDomain B]
  [Algebra A B] (G : Type v) [Group G] [Finite G] [MulSemiringAction G B]
  (Q : Ideal B) [Q.IsPrime] (hQ : Q ≠ ⊥)
  (p : ℕ) [ExpChar (IsLocalRing.ResidueField (Localization.AtPrime Q)) p]
  (hq : ∃ a : ℕ, finiteIdealNormalizationExponent A B G Q hQ = p ^ a)
include p hq
theorem finiteIdealCanonicalTameCharacterGroupMap_surjective :
    Function.Surjective (finiteIdealCanonicalTameCharacterGroupMap A B G Q hQ)