Exists pow smul integer mem span
IsNonarchimedeanLocalField.exists_pow_smul_integer_mem_span
Plain-language statement
Bounded denominators: if b is any finite K-basis of L and ϖ is a uniformiser of K, then a large enough power of ϖ multiplies every integer of L into the 𝒪[K]-lattice spanned by b. This is the key analytic input both for Module.Finite 𝒪[K] 𝒪[L] (see below) and, applied to a normal basis, for the construction of an open cohomologi...
Exact Lean statement
theorem exists_pow_smul_integer_mem_span {ι : Type*} [Finite ι] (b : Module.Basis ι K L)
{ϖ : 𝒪[K]} (hϖ : Irreducible ϖ) :
∃ m : ℕ, ∀ x ∈ 𝒪[L], (ϖ : K) ^ m • x ∈ Submodule.span 𝒪[K] (Set.range b)Formal artifact
Lean source
theorem exists_pow_smul_integer_mem_span {ι : Type*} [Finite ι] (b : Module.Basis ι K L) {ϖ : 𝒪[K]} (hϖ : Irreducible ϖ) : ∃ m : ℕ, ∀ x ∈ 𝒪[L], (ϖ : K) ^ m • x ∈ Submodule.span 𝒪[K] (Set.range b) := by have := Fintype.ofFinite ι let : UniformSpace K := IsTopologicalAddGroup.rightUniformSpace K let : IsUniformAddGroup K := isUniformAddGroup_of_addCommGroup (G := K) let := rankOneOfIoo K default let : NontriviallyNormedField K := Valued.toNontriviallyNormedField (L := K) _ have hcont : Continuous (b.equivFun : L → ι → K) := IsModuleTopology.continuous_of_linearMap (b.equivFun : L →ₗ[K] ι → K) have hcpt : IsCompact (𝒪[L] : Set L) := IsNonarchimedeanLocalField.isCompact_closedBall L 1 obtain ⟨C, hC⟩ := isBounded_iff_forall_norm_le.mp (hcpt.image hcont).isBounded simp only [Module.Basis.equivFun_apply, Set.mem_image, SetLike.mem_coe, forall_exists_index, and_imp, forall_apply_eq_imp_iff₂] at hC obtain ⟨m, hm⟩ : ∃ m : ℕ, ‖(ϖ : K)‖ ^ m < (max C 1)⁻¹ := exists_pow_lt_of_lt_one (by positivity) <| Valued.toNormedField.norm_lt_one_iff.mpr (Valuation.integer.v_irreducible_lt_one hϖ) refine ⟨m, fun x hx ↦ (b.mem_span_iff_repr_mem _ _).2 fun i ↦ ⟨⟨(ϖ : K) ^ m * b.repr x i, Valuation.mem_integer_iff _ _|>.2 <| Valued.toNormedField.norm_le_one_iff.1 ?_⟩, by simp⟩⟩ grw [norm_mul, norm_pow, ((norm_le_pi_norm _ i).trans (hC _ hx)).trans (le_max_left _ 1), hm, inv_mul_cancel₀ (by positivity)]- Project
- Class Field Theory
- License
- Apache-2.0
- Commit
- f18cd7fd1575
- Source
- ClassFieldTheory/IsNonarchimedeanLocalField/Basic.lean:361-384
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