Documentation

Mathlib.NumberTheory.NumberField.Completion.InfinitePlace

The completion of a number field at an infinite place #

This file contains the completion of a number field at an infinite place. This is ultimately achieved by applying the UniformSpace.Completion functor, however each infinite place induces its own UniformSpace instance on the number field, so the inference system cannot automatically infer these. A common approach to handle the ambiguity that arises from having multiple sources of instances is through the use of type synonyms. In this case, we use the type synonym WithAbs of a semiring. In particular this type synonym depends on an absolute value, which provides a systematic way of assigning and inferring instances of the semiring that also depend on an absolute value. The completion of a field at multiple absolute values is defined in Mathlib/Analysis/Normed/Field/WithAbs.lean as AbsoluteValue.Completion. The completion of a number field at an infinite place is then derived in this file, as InfinitePlace is a subtype of AbsoluteValue.

Main definitions #

Main results #

Tags #

number field, embeddings, infinite places, completion, absolute value

The completion of a number field at an infinite place, as a one-field structure wrapping the completion v.1.Completion of K at the underlying absolute value.

Instances For

    Completion.toCompletion and Completion.ofCompletion as an equivalence.

    Equations
    • One or more equations did not get rendered due to their size.
    Instances For
      @[simp]
      theorem NumberField.InfinitePlace.Completion.equivCompletion_symm_apply_toCompletion {K : Type u_1} [Field K] (v : InfinitePlace K) (toCompletion : (↑v).Completion) :
      ((equivCompletion v).symm toCompletion).toCompletion = toCompletion
      @[instance_reducible]
      Equations
      • One or more equations did not get rendered due to their size.

      Completion.toCompletion as a ring isomorphism onto the underlying completion.

      Equations
      Instances For
        @[simp]
        @[simp]
        @[simp]
        theorem NumberField.InfinitePlace.Completion.norm_ofCompletion {K : Type u_1} [Field K] (v : InfinitePlace K) (x : (↑v).Completion) :
        { toCompletion := x } = x
        @[instance_reducible]
        Equations
        @[instance_reducible]

        Coercion of an element of WithAbs v.1 into the completion.

        Equations
        @[instance_reducible]
        noncomputable instance NumberField.InfinitePlace.Completion.instCoe {K : Type u_1} [Field K] (v : InfinitePlace K) :

        Coercion of an element of K into the completion.

        Equations
        @[simp]
        theorem NumberField.InfinitePlace.Completion.coe_toCompletion {K : Type u_1} [Field K] (v : InfinitePlace K) (x : WithAbs v) :
        { toCompletion := x }.toCompletion = x
        theorem NumberField.InfinitePlace.Completion.coe_zero {K : Type u_1} [Field K] (v : InfinitePlace K) :
        { toCompletion := (WithAbs.toAbs (↑v) 0) } = 0
        theorem NumberField.InfinitePlace.Completion.coe_one {K : Type u_1} [Field K] (v : InfinitePlace K) :
        { toCompletion := (WithAbs.toAbs (↑v) 1) } = 1
        theorem NumberField.InfinitePlace.Completion.coe_add {K : Type u_1} [Field K] (v : InfinitePlace K) (x y : K) :
        { toCompletion := (WithAbs.toAbs (↑v) (x + y)) } = { toCompletion := (WithAbs.toAbs (↑v) x) } + { toCompletion := (WithAbs.toAbs (↑v) y) }
        theorem NumberField.InfinitePlace.Completion.coe_mul {K : Type u_1} [Field K] (v : InfinitePlace K) (x y : K) :
        { toCompletion := (WithAbs.toAbs (↑v) (x * y)) } = { toCompletion := (WithAbs.toAbs (↑v) x) } * { toCompletion := (WithAbs.toAbs (↑v) y) }
        theorem NumberField.InfinitePlace.Completion.continuous_coe {K : Type u_1} [Field K] (v : InfinitePlace K) :
        Continuous fun (x : WithAbs v) => { toCompletion := x }
        theorem NumberField.InfinitePlace.Completion.denseRange_coe {K : Type u_1} [Field K] (v : InfinitePlace K) :
        DenseRange fun (x : WithAbs v) => { toCompletion := x }
        theorem NumberField.InfinitePlace.Completion.induction_on {K : Type u_1} [Field K] (v : InfinitePlace K) {p : v.CompletionProp} (x : v.Completion) (hp : IsClosed {x : v.Completion | p x}) (ih : ∀ (a : WithAbs v), p { toCompletion := a }) :
        p x

        Induction on the completion of a number field at an infinite place: a closed property that holds on the image of K holds everywhere.

        @[instance_reducible]
        Equations
        • One or more equations did not get rendered due to their size.
        @[simp]
        theorem NumberField.InfinitePlace.Completion.algebraMap_apply {K : Type u_1} [Field K] (v : InfinitePlace K) (k : K) :
        (algebraMap K v.Completion) k = { toCompletion := (WithAbs.toAbs (↑v) k) }
        theorem NumberField.InfinitePlace.Completion.norm_coe {K : Type u_1} [Field K] (v : InfinitePlace K) (x : WithAbs v) :
        { toCompletion := x } = v ((WithAbs.equiv v) x)
        theorem NumberField.InfinitePlace.Completion.WithAbs.ratCast_equiv (v : InfinitePlace ) (x : WithAbs v) :
        ((WithAbs.equiv v) x) = { toCompletion := x }

        The coercion from the rationals to its completion along an infinite place is Rat.cast.

        The completion of a number field at an infinite place is locally compact.

        The embedding associated to an infinite place extended to an embedding v.Completion →+* ℂ.

        Equations
        Instances For

          The embedding K →+* ℝ associated to a real infinite place extended to v.Completion →+* ℝ.

          Equations
          Instances For
            @[simp]
            theorem NumberField.InfinitePlace.Completion.extensionEmbedding_coe {K : Type u_1} [Field K] (v : InfinitePlace K) (x : WithAbs v) :
            (extensionEmbedding v) { toCompletion := x } = v.embedding ((WithAbs.equiv v) x)

            The embedding v.Completion →+* ℝ at a real infinite place is an isometry.

            The embedding v.Completion →+* ℂ has closed image inside .

            The embedding v.Completion →+* ℝ associated to a real infinite place has closed image inside .

            If v is a complex infinite place, then the embedding v.Completion →+* ℂ is surjective.

            If v is a complex infinite place, then the embedding v.Completion →+* ℂ is bijective.

            If the infinite place v is complex, then v.Completion is isometric to .

            Equations
            Instances For

              If v is a real infinite place, then the embedding v.Completion →+* ℝ is surjective.

              If v is a real infinite place, then the embedding v.Completion →+* ℝ is bijective.

              The ring isomorphism v.Completion ≃+* ℝ, when v is real, given by the bijection v.Completion →+* ℝ.

              Equations
              Instances For

                If the infinite place v is real, then v.Completion is isometric to .

                Equations
                Instances For
                  theorem NumberField.InfinitePlace.Completion.algebraMap_eq_coe {K : Type u_1} [Field K] {v : InfinitePlace K} {L : Type u_2} [Field L] [Algebra K L] (w : InfinitePlace L) (x : WithAbs v) :
                  (algebraMap (WithAbs v) w.Completion) x = { toCompletion := ((algebraMap (WithAbs v) (WithAbs w)) x) }
                  @[simp]
                  theorem NumberField.InfinitePlace.Completion.algebraMap_coe {K : Type u_1} [Field K] {v : InfinitePlace K} {L : Type u_2} [Field L] [Algebra K L] (w : InfinitePlace L) [Algebra v.Completion w.Completion] [IsScalarTower K v.Completion w.Completion] (x : WithAbs v) :
                  (algebraMap v.Completion w.Completion) { toCompletion := x } = { toCompletion := ((algebraMap (WithAbs v) (WithAbs w)) x) }

                  Assume that w.Completion forms an algebra over v.Completion with continuous scalar action, such that IsScalarTower K v.Completion w.Completion. If w.embedding : L →+* ℂ extends v.embedding : K →+* ℂ, then the corresponding embeddings to completions are also extensions.