The -adic closure of the global units lies in
ProvedLeopoldt.closure_range_diagonalUnits_subset_unitClosureleopoldtnumber-theoryp-adic
Let be a number field, a prime, the semilocal units at and the diagonal embedding. Then the topological closure of in is contained in
This is the inclusion of the identity in §1.1 of the source; it follows because the right-hand side is a closed subgroup containing . (The reverse inclusion can fail by a finite group of roots of unity of order prime to — e.g. for , the intersection is while — which does not affect -ranks.)
Preamble
import Definitions.Def_LeopoldtDefect
Formal statement
namespace Leopoldt
theorem closure_range_diagonalUnits_subset_unitClosure (p : ℕ) [Fact p.Prime] (K : Type*)
[Field K] [NumberField K] :
closure (Set.range (diagonalUnits p K)) ⊆ (unitClosure p K : Set (SemilocalUnits p K)) := by sorry
end LeopoldtSource
P. Mihăilescu, On CM ℤ_p-extensions and the Leopoldt conjecture for CM fields, arXiv:1105.4544, §1.1 (definition Ē = closure(ι(E)) = ⋂_{n>0} ι(E)·U^{p^n})