Module

MixedCharPrincipalUnitLogBound.lean

Nyll.ValuedFieldTheory.LocalField.Analytic.MixedCharPrincipalUnitLogBound
1 declaration indexed from sourceView source ↗

A lower bound for valuations in the principal-unit logarithm image

The integer sequence n - e * v_p(n), for positive n, has an attained minimum. Every nonzero principal-unit logarithm has integer valuation at least that minimum. The bound is uniform over all principal units, including when the residue field is infinite.

Declarations

LocalFieldTheory.DiscreteValuationField.MultiplicativeIntegerValuation.exists_principalUnitLog_denominator_min_bound

The exact denominator minimum bounds every nonzero logarithmic value.

Source context 3 commands

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

namespace LocalFieldTheory.DiscreteValuationField.MultiplicativeIntegerValuation
universe u
variable {K : Type u} [Field K] [CharZero K]
theorem exists_principalUnitLog_denominator_min_bound
    (v : _root_.Valuation K (WithZero (Multiplicative ℤ)))
    [ValuationTheory.DiscreteValuationField.Valuation.IsCompleteDiscrete v]
    (p : ℕ) [Fact p.Prime] [CharP (IsLocalRing.ResidueField v.valuationSubring) p] :
    ∃ m : ℕ,
      (∀ n : ℕ,
        ((m + 1 : ℕ) : ℤ) - (v.residueRamificationIndex p : ℤ) *
            (padicValNat p (m + 1) : ℤ) ≤
          ((n + 1 : ℕ) : ℤ) - (v.residueRamificationIndex p : ℤ) *
            (padicValNat p (n + 1) : ℤ)) ∧
      ∀ u : CompleteDVF.higherPrincipalUnitGroup (completeDVFOfWithZeroValuation v) 1,
        ∀ hu : (principalUnitLogOfMixedChar v p u).toAdd ≠ 0,
          ((m + 1 : ℕ) : ℤ) - (v.residueRamificationIndex p : ℤ) *
              (padicValNat p (m + 1) : ℤ) ≤
            (ofWithZeroValuation v).val
              (Units.mk0 (principalUnitLogOfMixedChar v p u).toAdd hu)