Module

RealProTwoInitialPresentation.lean

Nyll.SawinTotallyRealTowers.RealProTwoInitialPresentation
3 declarations indexed from sourceView source ↗

A five-generator minimal presentation of the actual initial group

Choose a presentation attaining the least relation count constructed in S1. Minimality identifies its displayed generator count with the actual rank five. The same presentation, including its free source and relators, is retained.

Declarations

ClassFieldTower.Sawin.initialPresentationPrimeTwo
Source context 2 commands

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

namespace ClassFieldTower.Sawin
open ProCGroups ClassFieldTower.ProP
instance initialPresentationPrimeTwo : Fact (Nat.Prime 2)
ClassFieldTower.Sawin.initialPresentationIsGalois
Source context 3 commands

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

namespace ClassFieldTower.Sawin
open ProCGroups ClassFieldTower.ProP
private local instance initialPresentationPrimeTwo : Fact (Nat.Prime 2) := ⟨Nat.prime_two⟩
instance initialPresentationIsGalois :
    IsGalois ℚ (maximalRealProPOutside 2 sawinRationalPrimeSupport)
ClassFieldTower.Sawin.exists_sawinInitialProTwo_minimalPresentation

The initial arithmetic group has an actual minimal presentation on five generators and at most six relators. The chosen relator count attains the least relation rank supplied by S1.

Source context 4 commands

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

namespace ClassFieldTower.Sawin
open ProCGroups ClassFieldTower.ProP
private local instance initialPresentationPrimeTwo : Fact (Nat.Prime 2) := ⟨Nat.prime_two⟩
private local instance initialPresentationIsGalois :
    IsGalois ℚ (maximalRealProPOutside 2 sawinRationalPrimeSupport) :=
  maximalRealProPOutside_isGalois 2 sawinRationalPrimeSupport
theorem exists_sawinInitialProTwo_minimalPresentation :
    ∃ sourceData : FreeProC.EpimorphicallyFreeProCGroupOnConvergingSetData.{0, 0}
      (FiniteGroupClass.pGroup 2),
      ∃ r : ℕ, ∃ P : FiniteProPPresentation 2 5 r sourceData
        (maximalRealProPOutside 2 sawinRationalPrimeSupport ≃ₐ[ℚ]
          maximalRealProPOutside 2 sawinRationalPrimeSupport),
        P.IsMinimal ∧ r ≤ 6