Module

ComplexConfiguration.lean

Nyll.AnabelianGeometry.ProjectiveLine.ComplexConfiguration
4 declarations indexed from sourceView source ↗

The unit-circle exceptional locus

A complex parameter whose value and complement both have norm one lies on the quadratic exceptional locus. This supplies the archimedean step for the simultaneous torsion case in multiplicative reconstruction.

Imports6
  • Mathlib.Analysis.Complex.Basic
  • Mathlib.GroupTheory.OrderOfElement
  • Mathlib.Tactic.Linarith
  • Mathlib.Tactic.LinearCombination
  • Mathlib.Tactic.FieldSimp
  • Mathlib.Tactic.Ring
Imported by2

Declarations

AnabelianGeometry.ProjectiveLine.sq_sub_add_one_eq_zero_of_norm_eq_one

Two unit-circle conditions force the sixth-cyclotomic quadratic.

Source context 1 command

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

namespace AnabelianGeometry.ProjectiveLine
theorem sq_sub_add_one_eq_zero_of_norm_eq_one {z : ℂ}
    (hz : ‖z‖ = 1) (hc : ‖1 - z‖ = 1) : z ^ 2 - z + 1 = 0
AnabelianGeometry.ProjectiveLine.sq_sub_add_one_eq_zero_of_isOfFinOrder

A complex parameter and its complement cannot both be torsion outside the quadratic exceptional locus.

Source context 1 command

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

namespace AnabelianGeometry.ProjectiveLine
theorem sq_sub_add_one_eq_zero_of_isOfFinOrder {z : ℂ}
    (hz : IsOfFinOrder z) (hc : IsOfFinOrder (1 - z)) : z ^ 2 - z + 1 = 0
AnabelianGeometry.ProjectiveLine.sq_sub_add_one_eq_zero_of_isOfFinOrder_of_embedding

The torsion exceptional-locus calculation descends through any complex embedding, in particular through an embedding of a number field.

Source context 1 command

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

namespace AnabelianGeometry.ProjectiveLine
theorem sq_sub_add_one_eq_zero_of_isOfFinOrder_of_embedding
    {K : Type*} [Field K] (e : K →+* ℂ) {x : K}
    (hx : IsOfFinOrder x) (hc : IsOfFinOrder (1 - x)) : x ^ 2 - x + 1 = 0
AnabelianGeometry.ProjectiveLine.sq_sub_add_one_eq_zero_of_complement_norms

If the complements of a nonzero parameter and its inverse both have norm one, that parameter lies on the same quadratic exceptional locus.

Source context 1 command

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

namespace AnabelianGeometry.ProjectiveLine
theorem sq_sub_add_one_eq_zero_of_complement_norms {z : ℂ} (hz : z ≠ 0)
    (hc : ‖1 - z‖ = 1) (hi : ‖1 - z⁻¹‖ = 1) : z ^ 2 - z + 1 = 0