Module

FiniteFree.lean

Nyll.GaloisCohomology.Kummer.Concrete.Cyclotomic.ProfiniteUnitDecomposition.FiniteFree
1 declaration indexed from sourceView source ↗

Compiled finite/free collection stage of the profinite-unit decomposition

Declarations

KummerTheory.ProfiniteUnitDecomposition.Internal.finiteFreeSplit

Collect the finite and torsion-free coordinates of the local product.

Source context 4 commands

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

open scoped Topology
noncomputable section
namespace KummerTheory.ProfiniteUnitDecomposition.Internal
open LocalFieldTheory.Padic
def finiteFreeSplit :
    ((p : Nat.Primes) →
      padicUnitFiniteFactor p.1 × Multiplicative ℤ_[p.1]) ≃ₜ*
    ((p : Nat.Primes) → Multiplicative ℤ_[p.1]) ×
      CyclotomicFinitePart where
  toFun x := (fun p => (x p).2, fun p => (x p).1)
  invFun x p := (x.2 p, x.1 p)
  left_inv _ := rfl
  right_inv _ := rfl
  map_mul' _ _ := rfl
  continuous_toFun :=
    (continuous_pi fun p =>
      continuous_snd.comp (continuous_apply p)).prodMk
        (continuous_pi fun p =>
          continuous_fst.comp (continuous_apply p))
  continuous_invFun :=
    continuous_pi fun p =>
      ((continuous_apply p).comp continuous_snd).prodMk
        ((continuous_apply p).comp continuous_fst)