RamificationTheory.HilbertRamification.ValuationSubring.mem_ramificationGroup_iff_principalUnitMultipliers
Actual Hilbert ramification is exactly the principal-unit multiplier predicate used by the ring-only DVR character kernel.
Source context 3 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
namespace RamificationTheory.HilbertRamification.ValuationSubring
universe u vLean source · statement
theorem mem_ramificationGroup_iff_principalUnitMultipliers
(K : Type u) {L : Type v} [Field K] [Field L] [Algebra K L]
(V : _root_.ValuationSubring L) (σ : inertiaGroup K V) :
σ ∈ ramificationGroup K V ↔
∀ x : V, ∃ a : Vˣ,
(σ : decompositionGroup K V) • x = x * (a : V) ∧
(a : V) - 1 ∈ IsLocalRing.maximalIdeal V