Module

ProfiniteIntegerUnits.lean

Nyll.GaloisCohomology.ProfiniteIntegers.ProfiniteIntegerUnits
5 declarations indexed from sourceView source ↗

Units of the profinite integers

This file upgrades the prime-product Chinese-remainder equivalence for ℤ̂ to topological additive, multiplicative, and unit-group equivalences.

Declarations

ClassFormation.zHatContinuousMulEquivPrimeProduct

The Chinese-remainder isomorphism as a topological monoid equivalence.

Source context 3 commands

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

open scoped Topology
noncomputable section
namespace ClassFormation
def zHatContinuousMulEquivPrimeProduct :
    ZHat ≃ₜ* ProfiniteIntegerPrimeProduct
ClassFormation.zHatContinuousAddEquivPrimeProduct

The additive form of the topological Chinese-remainder isomorphism.

Source context 3 commands

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

open scoped Topology
noncomputable section
namespace ClassFormation
def zHatContinuousAddEquivPrimeProduct :
    ZHat ≃ₜ+ ProfiniteIntegerPrimeProduct
Source context 3 commands

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

open scoped Topology
noncomputable section
namespace ClassFormation
instance (p : Nat.Primes) : Fact p.1.Prime
ClassFormation.zHatUnitsContinuousMulEquivPrimeProduct

The canonical topological Chinese-remainder equivalence on unit groups.

Source context 4 commands

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

open scoped Topology
noncomputable section
namespace ClassFormation
local instance (p : Nat.Primes) : Fact p.1.Prime :=
  ⟨p.2⟩
def zHatUnitsContinuousMulEquivPrimeProduct :
    ZHatˣ ≃ₜ* ((p : Nat.Primes) → ℤ_[p.1]ˣ)
ClassFormation.zHatUnitsContinuousMulEquivPrimeProduct_coe_apply

On underlying ring elements, the unit-group Chinese-remainder equivalence is the canonical p-adic coordinate map.

Source context 4 commands

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

open scoped Topology
noncomputable section
namespace ClassFormation
local instance (p : Nat.Primes) : Fact p.1.Prime :=
  ⟨p.2⟩
theorem zHatUnitsContinuousMulEquivPrimeProduct_coe_apply
    (u : ZHatˣ) (p : Nat.Primes) :
    (zHatUnitsContinuousMulEquivPrimeProduct u p : ℤ_[p.1]) =
      zHatToPadicInt p (u : ZHat)