Exists valuation algebra Map eq valuation pow
exists_valuation_algebraMap_eq_valuation_pow
Plain-language statement
Andrew's Lemma : Density for algebraic extensions.
Exact Lean statement
theorem exists_valuation_algebraMap_eq_valuation_pow
(K : Type*) {L : Type*} [Field K] [Field L] [Algebra K L] [ValuativeRel L]
[Algebra.IsAlgebraic K L] (y : L) :
∃ x n, n ≠ 0 ∧ valuation L (algebraMap K L x) = valuation L y ^ nFormal artifact
Lean source
theorem exists_valuation_algebraMap_eq_valuation_pow (K : Type*) {L : Type*} [Field K] [Field L] [Algebra K L] [ValuativeRel L] [Algebra.IsAlgebraic K L] (y : L) : ∃ x n, n ≠ 0 ∧ valuation L (algebraMap K L x) = valuation L y ^ n := by by_cases hy : y = 0 · use 0, 1, one_ne_zero simp [hy] by_contra! H have := congr(valuation L $(minpoly.aeval K y)) rw [Polynomial.aeval_eq_sum_range, Valuation.sum_eq_iSup] at this; swap · simp only [Finset.mem_range, Nat.lt_succ_iff, ne_eq, map_eq_zero, smul_eq_zero, pow_eq_zero_iff', hy, false_and, or_false] intros i hi j hj hij hi' hj' e wlog hij' : i ≤ j generalizing i j · exact this j hj i hi (Ne.symm hij) hj' hi' e.symm (by omega) obtain ⟨k, rfl⟩ := exists_add_of_le hij' simp [Algebra.smul_def] at e apply H ((minpoly K y).coeff i / (minpoly K y).coeff (i + k)) k (by simpa using hij) apply mul_left_injective₀ (b := (valuation L) y ^ i) (by simp [hy]) simp [*, -mul_eq_mul_right_iff, div_mul_eq_mul_div, pow_add, mul_comm] · simp only [map_zero, ← bot_eq_zero, Finset.sup_eq_bot_iff] at this simp only [Finset.mem_range, Function.comp_apply, bot_eq_zero, map_eq_zero, smul_eq_zero, pow_eq_zero_iff', hy, ne_eq, false_and, or_false, Nat.lt_succ_iff] at this exact minpoly.coeff_zero_ne_zero (Algebra.IsIntegral.isIntegral _) hy (this 0 (by simp))- Project
- Class Field Theory
- License
- Apache-2.0
- Commit
- f18cd7fd1575
- Source
- ClassFieldTheory/LocalCFT/Continuity.lean:52-75
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Source project: Class Field Theory
Person-level attribution pending.