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Project-declaredLean 4.32.0 · mathlib@249c48c2

Int Valuation comap

IsDedekindDomain.HeightOneSpectrum.intValuation_comap

Plain-language statement

If w | v then for a ∈ A we have w(a)=v(a)^e where e is the ramification index.

Exact Lean statement

lemma intValuation_comap (hAB : Function.Injective (algebraMap A B))
    (w : HeightOneSpectrum B) (x : A) :
    (under A w).intValuation x ^
    (Ideal.ramificationIdx' (under A w).asIdeal w.asIdeal) =
    w.intValuation (algebraMap A B x)

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma intValuation_comap (hAB : Function.Injective (algebraMap A B))    (w : HeightOneSpectrum B) (x : A) :    (under A w).intValuation x ^    (Ideal.ramificationIdx' (under A w).asIdeal w.asIdeal) =    w.intValuation (algebraMap A B x) := by  classical  have h_ne_zero := ramificationIdx_ne_zero A B hAB w  by_cases hx : x = 0  · simpa [hx]  simp only [intValuation, Valuation.coe_mk, MonoidWithZeroHom.coe_mk, ZeroHom.coe_mk]  change (ite _ _ _) ^ _ = ite _ _ _  rw [map_eq_zero_iff _ hAB, if_neg hx, if_neg hx,  Set.image_singleton,  Ideal.map_span,    mk_count_factors_map _ _ hAB, mul_comm, WithZero.exp, WithZero.exp]  simp
Project
Fermat's Last Theorem
License
Apache-2.0
Commit
8dd808888295
Source
FLT/DedekindDomain/IntegralClosure.lean:96-109

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Project-declaredLean 4.32.0

Eq finsum quotient out of bij On

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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.

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Project-declaredLean 4.32.0

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Plain-language statement

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Source project: Fermat's Last Theorem

Person-level attribution pending.

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