All proofs
Project-declaredLean 4.32.0 · mathlib@249c48c2

Quadratic Twist Var Change base Change map

WeierstrassCurve.quadraticTwistVarChange_baseChange_map

Plain-language statement

The M-level form of the twist's defining cocycle: any σ ∈ Aut(M/K) not fixing L pointwise (i.e. with χ(σ) = -1) conjugates the base change to M of quadraticTwistVarChange by the automorphism [-1] of E. This is the base change of quadraticTwistVarChange_map.

Exact Lean statement

lemma quadraticTwistVarChange_baseChange_map {σ : M ≃ₐ[K] M}
    (hσ : ¬ ∀ x : L, σ (algebraMap L M x) = algebraMap L M x) :
    ((E.quadraticTwistVarChange L).baseChange M).map σ.toAlgHom.toRingHom
      = (E.quadraticTwistVarChange L).baseChange M * (E.baseChange M).negVariableChange

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma quadraticTwistVarChange_baseChange_map {σ : M ≃ₐ[K] M}    (hσ : ¬  x : L, σ (algebraMap L M x) = algebraMap L M x) :    ((E.quadraticTwistVarChange L).baseChange M).map σ.toAlgHom.toRingHom      = (E.quadraticTwistVarChange L).baseChange M * (E.baseChange M).negVariableChange := by  obtain σ₀, hσ₀ := exists_algEquiv_ne_one K L  have hres : σ.restrictNormal L = σ₀ :=    (algEquiv_eq_one_or_eq K L hσ₀ _).resolve_left      (fun h  hσ ((forall_apply_algebraMap_iff_restrictNormal_eq_one K L M σ).mpr h))  have hcomp : σ.toAlgHom.toRingHom.comp (algebraMap L M)      = (algebraMap L M).comp σ₀.toAlgHom.toRingHom := by    ext l    have h := (AlgEquiv.restrictNormal_commutes σ L l).symm    rw [hres] at h    simpa using h  have e1 : ((E.quadraticTwistVarChange L).baseChange M).map σ.toAlgHom.toRingHom      = (E.quadraticTwistVarChange L).map (σ.toAlgHom.toRingHom.comp (algebraMap L M)) :=    (E.quadraticTwistVarChange L).map_map (algebraMap L M) σ.toAlgHom.toRingHom  have e2 : ((E.quadraticTwistVarChange L) * (E.baseChange L).negVariableChange).map        (algebraMap L M)      = (E.quadraticTwistVarChange L).baseChange M        * (E.baseChange L).negVariableChange.map (algebraMap L M) :=    map_mul (VariableChange.mapHom (algebraMap L M)) _ _  rw [e1, hcomp,  VariableChange.map_map, E.quadraticTwistVarChange_map L hσ₀, e2,    negVariableChange_map, baseChange_map_algebraMap]
Project
Fermat's Last Theorem
License
Apache-2.0
Commit
8dd808888295
Source
FLT/KnownIn1980s/EllipticCurves/QuadraticTwists/QuadraticTwists.lean:620-643

Reuse this declaration

Bring the exact result into your workflow

The import identifies the source module. Your project still needs the pinned package dependency shown on this page.

What this badge means

This completion status comes from the project or community source. It has not yet been represented here as an independent rebuild and axiom audit.

Continue in this project

Related declarations

Project-declaredLean 4.32.0

Eq finsum quotient out of bij On

AbstractHeckeOperator.eq_finsum_quotient_out_of_bijOn'

Plain-language statement

If a is fixed by V then ∑ᶠ g ∈ s, g • a is independent of the choice s of coset representatives in G for a subset of G ⧸ V

number theoryarithmetic geometryFermat's Last Theorem

Source project: Fermat's Last Theorem

Person-level attribution pending.

View proof record
Project-declaredLean 4.32.0

Comm Group no compact automorphisms

CommGroup.no_compact_automorphisms

Plain-language statement

A connected compact Hausdorff abelian topological group does not admit a nontrivial compact group of automorphisms.

number theoryarithmetic geometryFermat's Last Theorem

Source project: Fermat's Last Theorem

Person-level attribution pending.

View proof record