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norm_def_int
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fbarroero committed Dec 5, 2024
1 parent 8b4671c commit 4e978f3
Showing 1 changed file with 3 additions and 3 deletions.
6 changes: 3 additions & 3 deletions Mathlib/NumberTheory/NumberField/FinitePlaces.lean
Original file line number Diff line number Diff line change
Expand Up @@ -123,7 +123,7 @@ theorem FinitePlace.norm_def' (x : K) : ‖embedding v x‖ = toNNReal (norm_ne_

/-- The norm of the image after the embedding associated to `v` is equal to the norm of `v` raised
to the power of the `v`-adic valuation for integers. -/
theorem FinitePlace.norm_def'' (x : 𝓞 K) : ‖embedding v x‖ = toNNReal (norm_ne_zero v)
theorem FinitePlace.norm_def_int (x : 𝓞 K) : ‖embedding v x‖ = toNNReal (norm_ne_zero v)
(v.intValuationDef x) := by
rw [norm_def, vadicAbv_def, valuation_eq_intValuationDef]

Expand All @@ -136,14 +136,14 @@ theorem norm_le_one (x : 𝓞 K) : ‖embedding v x‖ ≤ 1 := by

/-- The `v`-adic norm of an integer is 1 if and only if it is not in the ideal. -/
theorem norm_eq_one_iff_not_mem (x : 𝓞 K) : ‖(embedding v) x‖ = 1 ↔ x ∉ v.asIdeal := by
rw [norm_def'', NNReal.coe_eq_one, toNNReal_eq_one_iff (v.intValuationDef x)
rw [norm_def_int, NNReal.coe_eq_one, toNNReal_eq_one_iff (v.intValuationDef x)
(norm_ne_zero v) (one_lt_norm v).ne', ← dvd_span_singleton,
← intValuation_lt_one_iff_dvd, not_lt]
exact (intValuation_le_one v x).ge_iff_eq.symm

/-- The `v`-adic norm of an integer is less than 1 if and only if it is in the ideal. -/
theorem norm_lt_one_iff_mem (x : 𝓞 K) : ‖embedding v x‖ < 1 ↔ x ∈ v.asIdeal := by
rw [norm_def'', NNReal.coe_lt_one, toNNReal_lt_one_iff (one_lt_norm v),
rw [norm_def_int, NNReal.coe_lt_one, toNNReal_lt_one_iff (one_lt_norm v),
intValuation_lt_one_iff_dvd]
exact dvd_span_singleton

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