Herbrand quotient of Lˣ #
If L/K is a finite cyclic extension of nonarchimedean local fields then h(Lˣ)=[L:K].
theorem
Rep.herbrandQuotient_isNonarchimedeanLocalField_integer_units
(K L : Type)
[Field K]
[ValuativeRel K]
[TopologicalSpace K]
[IsNonarchimedeanLocalField K]
[Field L]
[ValuativeRel L]
[TopologicalSpace L]
[IsNonarchimedeanLocalField L]
[Algebra K L]
[ValuativeExtension K L]
(G : Type)
[Group G]
[Finite G]
[IsCyclic G]
[MulSemiringAction G L]
[IsGaloisGroup G K L]
:
herbrand quotient of 𝒪[L]ˣ is 1
theorem
Rep.herbrandQuotient_isNonarchimedeanLocalField_units
(K L : Type)
[Field K]
[ValuativeRel K]
[TopologicalSpace K]
[IsNonarchimedeanLocalField K]
[Field L]
[ValuativeRel L]
[TopologicalSpace L]
[IsNonarchimedeanLocalField L]
[Algebra K L]
[ValuativeExtension K L]
(G : Type)
[Group G]
[Finite G]
[IsCyclic G]
[MulSemiringAction G L]
[IsGaloisGroup G K L]
:
(ofAlgebraAutOnUnits K L ↓ ↑(IsGaloisGroup.mulEquivAlgEquiv G K L)).herbrandQuotient = ↑(Module.finrank K L)
herbrand quotient of Lˣ is [L:K]