Module

AbsoluteFiniteQuotientTransitions.lean

Nyll.ClassFieldTheory.LocalClassFieldTheory.Infinite.AbsoluteFiniteQuotientTransitions
5 declarations indexed from sourceView source ↗

Transition maps between absolute finite quotients

The canonical finite quotient identifications commute with quotient transition on the profinite side and restriction on the Galois side.

Declarations

LocalClassFieldTheory.absoluteFiniteQuotientPreimage_mono

Pullback of open normal subgroups is monotone.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory
open RamificationTheory
variable {K : Type} [Field K]
theorem absoluteFiniteQuotientPreimage_mono
    {N M : OpenNormalSubgroup (localAbsoluteAbelianProfinite K)}
    (hNM : N ≤ M) :
    absoluteFiniteQuotientPreimage K N ≤
      absoluteFiniteQuotientPreimage K M
LocalClassFieldTheory.absoluteFiniteQuotientField_antitone

Inclusion of open normal subgroups reverses the corresponding fixed fields.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory
open RamificationTheory
variable {K : Type} [Field K]
theorem absoluteFiniteQuotientField_antitone
    {N M : OpenNormalSubgroup (localAbsoluteAbelianProfinite K)}
    (hNM : N ≤ M) :
    absoluteFiniteQuotientField K M ≤
      absoluteFiniteQuotientField K N
LocalClassFieldTheory.absoluteFiniteQuotientTransition

The canonical transition map between two finite quotients.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory
open RamificationTheory
variable {K : Type} [Field K]
def absoluteFiniteQuotientTransition
    {N M : OpenNormalSubgroup (localAbsoluteAbelianProfinite K)}
    (hNM : N ≤ M) :
    localAbsoluteAbelianProfinite K ⧸ N.toSubgroup →ₜ*
      localAbsoluteAbelianProfinite K ⧸ M.toSubgroup
LocalClassFieldTheory.absoluteFiniteQuotientTransition_mk

States the theorem absoluteFiniteQuotientTransition_mk.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory
open RamificationTheory
variable {K : Type} [Field K]
theorem absoluteFiniteQuotientTransition_mk
    {N M : OpenNormalSubgroup (localAbsoluteAbelianProfinite K)}
    (hNM : N ≤ M) (x : localAbsoluteAbelianProfinite K) :
    absoluteFiniteQuotientTransition hNM (QuotientGroup.mk x) =
      QuotientGroup.mk x
LocalClassFieldTheory.absoluteFiniteQuotientEquiv_transition

Under the finite quotient identifications, quotient transition is exactly restriction of automorphisms to the smaller fixed field.

Source context 5 commands

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

noncomputable section
namespace LocalClassFieldTheory
open LocalFieldTheory
open RamificationTheory
variable {K : Type} [Field K]
theorem absoluteFiniteQuotientEquiv_transition
    {N M : OpenNormalSubgroup (localAbsoluteAbelianProfinite K)}
    (hNM : N ≤ M) :
    (intermediateFieldRestrictContinuous K
      (absoluteFiniteQuotientField K M)
      (absoluteFiniteQuotientField K N)
      (absoluteFiniteQuotientField_antitone hNM)).comp
        (ContinuousMonoidHom.toContinuousMonoidHom
          (absoluteFiniteQuotientEquiv K N)) =
      (ContinuousMonoidHom.toContinuousMonoidHom
        (absoluteFiniteQuotientEquiv K M)).comp
          (absoluteFiniteQuotientTransition hNM)