Infinite-dimensional operator ridgelet transform

7.3. Neural-operator layers🔗

Example7.6
Statement uses 6
Statement dependency previews
Preview
Definition 2.2
Loading preview
Statement dependency preview content is loaded from the rendered-fragment cache.
Used by 2
Reverse dependency previews
Preview
Example 7.8
Loading preview
Reverse dependency preview content is loaded from the rendered-fragment cache.
✓L∃∀N

The standing hypotheses on (a,b), the norm \|A\|_\infty, the layer \mathcal F, the observable F_\varphi, the weight w_\varphi, the operator A:H\to L^2(m), the covariances S_y=Q-(1+\sigma_y^2)^{-1}(Qa_y)\otimes(Qa_y) with \sigma_y^2=\langle Qa_y,a_y\rangle, the Y-valued coefficient measure \Gamma=\iota_\#(b_y\,m(\mathrm dy)) with \iota(y)=(a_y,0), and the coefficient measure of the ReLU form, the pushforward of \phi''(b)\,b_y\,m(\mathrm dy)\,\mathrm db under (y,b)\mapsto(a_y,-b).

(i) \mathcal F=S_\beta[\Gamma] with \Gamma=\iota_\#(b_y\,m(\mathrm dy)), whose total variation is at most \int\|b_y\|m(\mathrm dy) and whose second parameter moment is at most \|A\|_\infty^2; hence width-N networks approximate \mathcal F at the rate N^{-1/2} in L^2(\zeta;Y), and for globally Lipschitz \beta the whole output function is approximated uniformly, \mathbb E\|F_N-\mathcal F\|_{C(K;Y)}\le\frac{B_1}{\sqrt N}(4|\beta(0)|+8\operatorname{Lip}(\beta)R_K\|A\|_\infty) with B_1=\int\|v_y\|\,m(\mathrm dy), the scalar observable having the same bound with \|w_\varphi\|_{L^1(m)} in place of B_1. (ii) For \beta=\Phi, F_\varphi\in\mathcal D_\alpha for every \alpha>0, F_QF_\varphi(\xi)=\int_\Omega w_\varphi(y)(1+\sigma_y^2)^{-1/2}e^{-\langle S_y\xi,\xi\rangle/2}\,m(\mathrm dy), R_\rho F_\varphi(a,c)=\int_\Omega w_\varphi(y)(1+\sigma_y^2)^{-1/2}(\rho*\phi_{\langle S_ya,a\rangle})(c)\,m(\mathrm dy), and S_y\ge(1+\|Q\|\|A\|_\infty^2)^{-1}Q; consequently F_QF_\varphi satisfies Definition 4.2, the reconstruction formulas of Theorem 4.8 hold for F_\varphi, and R_\rho F_\varphi synthesizes, with any real Lipschitz non-polynomial \beta', the target C_{\beta',\rho}^{(\alpha)}T_\alpha F_\varphi with the finite-width rate of Theorem 6.6; the same holds for \mathcal F as a Y-valued target. (iii) The Gaussian-activation layer is also the ReLU network \mathcal F(x)=\int_{\Omega\times\mathbb R}b_y\,\phi''(b)\operatorname{ReLU}(\langle a_y,x\rangle-b)\,m(\mathrm dy)\,\mathrm db with finite coefficient measure and finite moments. (iv) If A has infinite rank, \beta=\Phi, and w_\varphi>0 m-almost everywhere, then F_\varphi is not cylindrical.

Lean code for Example7.6●37 declarations
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_i_a.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [MeasurableSpace H]
      [BorelSpace H] {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (β : ℝ → ℝ)
      (hβc : Continuous β) (hβp : OperatorRidgelet.HasPolynomialGrowth β) :
      OperatorRidgelet.operatorLayer m a b β =
        OperatorRidgelet.integralNetwork (fun t => ↑(β t))
          (OperatorRidgelet.layerMeasure m a b)
    theorem OperatorRidgelet.Paper.ex_7_6_i_a.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (β : ℝ → ℝ) (hβc : Continuous β)
      (hβp :
        OperatorRidgelet.HasPolynomialGrowth
          β) :
      OperatorRidgelet.operatorLayer m a b β =
        OperatorRidgelet.integralNetwork
          (fun t => ↑(β t))
          (OperatorRidgelet.layerMeasure m a
            b)
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Network
    structure: `ℱ = S_β[Γ]` with the `Y`-valued measure `Γ = ι_#(b_y m(dy))`, `ι(y) = (a_y, 0)`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_i_b.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b) :
      OperatorRidgelet.totalVariation
          (OperatorRidgelet.layerMeasure m a b) ≤
        ∫⁻ (y : Ω), ‖b y‖ₑ ∂m
    theorem OperatorRidgelet.Paper.ex_7_6_i_b.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [MeasurableSpace H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b) :
      OperatorRidgelet.totalVariation
          (OperatorRidgelet.layerMeasure m a
            b) ≤
        ∫⁻ (y : Ω), ‖b y‖ₑ ∂m
    **Example [ex:7.6]** Neural-operator layer as an integral network.  The total
    variation of `Γ` is at most `∫ ‖b_y‖ m(dy)`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_i_c.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b) :
      ∫⁻ (θ : H × ℝ),
          ENNReal.ofReal
            (‖θ.1‖ ^ 2 +
              |θ.2| ^ 2) ∂(OperatorRidgelet.layerMeasure m a b).variation ≤
        ENNReal.ofReal (OperatorRidgelet.layerSupNorm a ^ 2) *
          OperatorRidgelet.totalVariation
            (OperatorRidgelet.layerMeasure m a b)
    theorem OperatorRidgelet.Paper.ex_7_6_i_c.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [MeasurableSpace H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b) :
      ∫⁻ (θ : H × ℝ),
          ENNReal.ofReal
            (‖θ.1‖ ^ 2 +
              |θ.2| ^
                2) ∂(OperatorRidgelet.layerMeasure
              m a b).variation ≤
        ENNReal.ofReal
            (OperatorRidgelet.layerSupNorm a ^
              2) *
          OperatorRidgelet.totalVariation
            (OperatorRidgelet.layerMeasure m a
              b)
    **Example [ex:7.6]** Neural-operator layer as an integral network.  The second
    parameter moment of `Γ` is at most `‖A‖_∞²`: `∫ (‖a‖² + c²) d|Γ| ≤ ‖A‖_∞² ‖Γ‖_TV`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_i_d.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (β : ℝ → ℝ) {L : NNReal}
      (hβ : LipschitzWith L β) (ζ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure ζ]
      (hζ : MeasureTheory.Integrable (fun x => ‖x‖ ^ 2) ζ) (n : ℕ)
      (hn : 0 < n) :
      ∫ (θ : Fin n → H × ℝ),
          ∫ (x : H),
            ‖OperatorRidgelet.polarSampledNetwork (fun t => ↑(β t))
                    (OperatorRidgelet.layerMeasure m a b) θ x -
                  OperatorRidgelet.operatorLayer m a b β x‖ ^
              2 ∂ζ ∂OperatorRidgelet.sampleLaw n
            (OperatorRidgelet.polarLaw
              (OperatorRidgelet.layerMeasure m a b)) ≤
        2 * (∫ (y : Ω), ‖b y‖ ∂m) ^ 2 / ↑n *
          (|β 0| ^ 2 +
            ↑L ^ 2 * (1 + ∫ (x : H), ‖x‖ ^ 2 ∂ζ) *
              OperatorRidgelet.layerSupNorm a ^ 2)
    theorem OperatorRidgelet.Paper.ex_7_6_i_d.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (β : ℝ → ℝ) {L : NNReal}
      (hβ : LipschitzWith L β)
      (ζ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure ζ]
      (hζ :
        MeasureTheory.Integrable
          (fun x => ‖x‖ ^ 2) ζ)
      (n : ℕ) (hn : 0 < n) :
      ∫ (θ : Fin n → H × ℝ),
          ∫ (x : H),
            ‖OperatorRidgelet.polarSampledNetwork
                    (fun t => ↑(β t))
                    (OperatorRidgelet.layerMeasure
                      m a b)
                    θ x -
                  OperatorRidgelet.operatorLayer
                    m a b β x‖ ^
              2 ∂ζ ∂OperatorRidgelet.sampleLaw
            n
            (OperatorRidgelet.polarLaw
              (OperatorRidgelet.layerMeasure m
                a b)) ≤
        2 * (∫ (y : Ω), ‖b y‖ ∂m) ^ 2 / ↑n *
          (|β 0| ^ 2 +
            ↑L ^ 2 *
                (1 + ∫ (x : H), ‖x‖ ^ 2 ∂ζ) *
              OperatorRidgelet.layerSupNorm
                  a ^
                2)
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Hence
    Corollary `cor:6.10` gives width-`n` networks approximating `ℱ` at the rate `n^{-1/2}` in
    `L²(ζ;Y)`: for globally Lipschitz `β`, the polar sampled network of `Γ` (samples from
    `p = |Γ|/V`) satisfies, by (b) and (c),
    `E‖f_n - ℱ‖²_{L²(ζ;Y)} ≤ 2 (∫‖b_y‖ m(dy))² n⁻¹ (|β(0)|² + Lip(β)² (1 + ∫‖x‖² dζ) ‖A‖_∞²)`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_i_e.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [MeasurableSpace H]
      [BorelSpace H] {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (β : ℝ → ℝ) {L : NNReal}
      (hβ : LipschitzWith L β) (φ : Y) (K : Set H) (hK : IsCompact K)
      (n : ℕ) (hn : 0 < n) :
      ∫ (θ : Fin n → H × ℝ),
          OperatorRidgelet.compactSupNorm K fun x =>
            OperatorRidgelet.polarSampledNetwork (fun t => ↑(β t))
                (OperatorRidgelet.layerMeasure m a
                  (OperatorRidgelet.layerWeight b φ))
                θ x -
              OperatorRidgelet.layerObservable m a b β φ
                x ∂OperatorRidgelet.sampleLaw n
            (OperatorRidgelet.polarLaw
              (OperatorRidgelet.layerMeasure m a
                (OperatorRidgelet.layerWeight b φ))) ≤
        (8 * ∫ (y : Ω), ‖OperatorRidgelet.layerWeight b φ y‖ ∂m) / √↑n *
          (|β 0| +
            ↑L * OperatorRidgelet.compactRadius K *
              OperatorRidgelet.layerSupNorm a)
    theorem OperatorRidgelet.Paper.ex_7_6_i_e.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (β : ℝ → ℝ) {L : NNReal}
      (hβ : LipschitzWith L β) (φ : Y)
      (K : Set H) (hK : IsCompact K) (n : ℕ)
      (hn : 0 < n) :
      ∫ (θ : Fin n → H × ℝ),
          OperatorRidgelet.compactSupNorm K
            fun x =>
            OperatorRidgelet.polarSampledNetwork
                (fun t => ↑(β t))
                (OperatorRidgelet.layerMeasure
                  m a
                  (OperatorRidgelet.layerWeight
                    b φ))
                θ x -
              OperatorRidgelet.layerObservable
                m a b β φ
                x ∂OperatorRidgelet.sampleLaw
            n
            (OperatorRidgelet.polarLaw
              (OperatorRidgelet.layerMeasure m
                a
                (OperatorRidgelet.layerWeight
                  b φ))) ≤
        (8 *
              ∫ (y : Ω),
                ‖OperatorRidgelet.layerWeight
                    b φ y‖ ∂m) /
            √↑n *
          (|β 0| +
            ↑L *
                OperatorRidgelet.compactRadius
                  K *
              OperatorRidgelet.layerSupNorm a)
    **Example [ex:7.6]** Neural-operator layer as an integral network.  For each
    `φ ∈ Y` and globally Lipschitz `β`, Theorem `thm:6.5` applied to
    `F_φ = S_β[Γ_φ]`, `Γ_φ = ι_#(w_φ m)`, gives for the polar sampled network `F_{φ,n}` of `Γ_φ`
    `E‖F_{φ,n} - F_φ‖_{C(K)} ≤ 8 ‖w_φ‖_{L¹(m)} n^{-1/2} (|β(0)| + Lip(β) R_K ‖A‖_∞)`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_i_f.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (β : ℝ → ℝ) {L : NNReal}
      (hβ : LipschitzWith L β) (K : Set H) (hK : IsCompact K) (n : ℕ)
      (hn : 0 < n) :
      ∫ (θ : Fin n → H × ℝ),
          OperatorRidgelet.compactSupNorm K fun x =>
            OperatorRidgelet.polarSampledNetwork (fun t => ↑(β t))
                (OperatorRidgelet.layerMeasure m a b) θ x -
              OperatorRidgelet.operatorLayer m a b β
                x ∂OperatorRidgelet.sampleLaw n
            (OperatorRidgelet.polarLaw
              (OperatorRidgelet.layerMeasure m a b)) ≤
        (∫ (y : Ω), ‖b y‖ ∂m) / √↑n *
          (4 * |β 0| +
            8 * ↑L * OperatorRidgelet.compactRadius K *
              OperatorRidgelet.layerSupNorm a)
    theorem OperatorRidgelet.Paper.ex_7_6_i_f.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (β : ℝ → ℝ) {L : NNReal}
      (hβ : LipschitzWith L β) (K : Set H)
      (hK : IsCompact K) (n : ℕ)
      (hn : 0 < n) :
      ∫ (θ : Fin n → H × ℝ),
          OperatorRidgelet.compactSupNorm K
            fun x =>
            OperatorRidgelet.polarSampledNetwork
                (fun t => ↑(β t))
                (OperatorRidgelet.layerMeasure
                  m a b)
                θ x -
              OperatorRidgelet.operatorLayer m
                a b β
                x ∂OperatorRidgelet.sampleLaw
            n
            (OperatorRidgelet.polarLaw
              (OperatorRidgelet.layerMeasure m
                a b)) ≤
        (∫ (y : Ω), ‖b y‖ ∂m) / √↑n *
          (4 * |β 0| +
            8 * ↑L *
                OperatorRidgelet.compactRadius
                  K *
              OperatorRidgelet.layerSupNorm a)
    **Example [ex:7.6]** Neural-operator layer as an integral network.  For globally
    Lipschitz `β`, Theorem `thm:6.5` applied to `F = S_β[Γ]`, `Γ = ι_#(v_y m)`, bounds
    the error of the polar sampled network uniformly on the whole output function:
    `E‖F_N - F‖_{C(K;Y)} ≤ B₁ N^{-1/2} (4|β(0)| + 8 Lip(β) R_K ‖A‖_∞)` with
    `B₁ = ∫ ‖v_y‖ m(dy)` (`eq:operator-layer-uniform`). 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_a.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ)
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b)
      (φ : Y) :
      OperatorRidgelet.MemSpectralCore μ
        (OperatorRidgelet.gaussianMixture N α)
        (OperatorRidgelet.layerObservable m a b OperatorRidgelet.gaussianFun
          φ)
    theorem OperatorRidgelet.Paper.ex_7_6_ii_a.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y) :
      OperatorRidgelet.MemSpectralCore μ
        (OperatorRidgelet.gaussianMixture N α)
        (OperatorRidgelet.layerObservable m a
          b OperatorRidgelet.gaussianFun φ)
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation `β = Φ`: `F_φ ∈ 𝒟_α` for every `α > 0`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_b.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [MeasurableSpace H] {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      (μ : MeasureTheory.Measure H) [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ)
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b)
      (φ : Y) (ξ : H) :
      OperatorRidgelet.gaussFourier μ
          (OperatorRidgelet.layerObservable m a b
            OperatorRidgelet.gaussianFun φ)
          ξ =
        ∫ (y : Ω),
          OperatorRidgelet.layerWeight b φ y *
            ↑((√(1 + inner ℝ (Q (a y)) (a y)))⁻¹ *
                Real.exp
                  (-inner ℝ ((OperatorRidgelet.layerCovariance Q a y) ξ) ξ /
                    2)) ∂m
    theorem OperatorRidgelet.Paper.ex_7_6_ii_b.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y) (ξ : H) :
      OperatorRidgelet.gaussFourier μ
          (OperatorRidgelet.layerObservable m
            a b OperatorRidgelet.gaussianFun
            φ)
          ξ =
        ∫ (y : Ω),
          OperatorRidgelet.layerWeight b φ y *
            ↑((√(1 +
                      inner ℝ (Q (a y))
                        (a y)))⁻¹ *
                Real.exp
                  (-inner ℝ
                        ((OperatorRidgelet.layerCovariance
                            Q a y)
                          ξ)
                        ξ /
                    2)) ∂m
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: with `σ_y² = ⟨Qa_y,a_y⟩` and `S_y = Q - (1+σ_y²)⁻¹ (Qa_y) ⊗ (Qa_y)`,
    `F_Q F_φ(ξ) = ∫ w_φ(y) (1+σ_y²)^{-1/2} e^{-⟨S_yξ,ξ⟩/2} m(dy)` (`eq:operator-layer-transform`). 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_c.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [MeasurableSpace H] {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      (μ : MeasureTheory.Measure H) [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (φ : Y) (p : H × ℝ) :
      OperatorRidgelet.ridgelet μ (⇑ρ)
          (OperatorRidgelet.layerObservable m a b
            OperatorRidgelet.gaussianFun φ)
          p =
        ∫ (y : Ω),
          OperatorRidgelet.layerWeight b φ y *
            ↑((√(1 + inner ℝ (Q (a y)) (a y)))⁻¹ *
                OperatorRidgelet.gaussianSmooth (⇑ρ)
                  (inner ℝ ((OperatorRidgelet.layerCovariance Q a y) p.1)
                    p.1)
                  p.2) ∂m
    theorem OperatorRidgelet.Paper.ex_7_6_ii_c.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y) (p : H × ℝ) :
      OperatorRidgelet.ridgelet μ (⇑ρ)
          (OperatorRidgelet.layerObservable m
            a b OperatorRidgelet.gaussianFun
            φ)
          p =
        ∫ (y : Ω),
          OperatorRidgelet.layerWeight b φ y *
            ↑((√(1 +
                      inner ℝ (Q (a y))
                        (a y)))⁻¹ *
                OperatorRidgelet.gaussianSmooth
                  (⇑ρ)
                  (inner ℝ
                    ((OperatorRidgelet.layerCovariance
                        Q a y)
                      p.1)
                    p.1)
                  p.2) ∂m
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: for every band-pass `ρ`,
    `R_ρ F_φ(a,c) = ∫ w_φ(y) (1+σ_y²)^{-1/2} (ρ * φ_{⟨S_ya,a⟩})(c) m(dy)`
    (`eq:operator-layer-transform`). 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_d.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3} [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b)
      (y : Ω) (ξ : H) :
      (1 + ‖Q‖ * OperatorRidgelet.layerSupNorm a ^ 2)⁻¹ * inner ℝ (Q ξ) ξ ≤
        inner ℝ ((OperatorRidgelet.layerCovariance Q a y) ξ) ξ
    theorem OperatorRidgelet.Paper.ex_7_6_ii_d.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (y : Ω) (ξ : H) :
      (1 +
              ‖Q‖ *
                OperatorRidgelet.layerSupNorm
                    a ^
                  2)⁻¹ *
          inner ℝ (Q ξ) ξ ≤
        inner ℝ
          ((OperatorRidgelet.layerCovariance Q
              a y)
            ξ)
          ξ
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: `S_y ≥ (1 + ‖Q‖ ‖A‖_∞²)⁻¹ Q`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_e.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (φ : Y) (I : Set ℝ) :
      OperatorRidgelet.IsFrequencyWindow (⇑ρ) I →
        OperatorRidgelet.IsRegularAlongRays
          (OperatorRidgelet.gaussianMixture N α) I
          (OperatorRidgelet.gaussFourier μ
            (OperatorRidgelet.layerObservable m a b
              OperatorRidgelet.gaussianFun φ))
    theorem OperatorRidgelet.Paper.ex_7_6_ii_e.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y) (I : Set ℝ) :
      OperatorRidgelet.IsFrequencyWindow (⇑ρ)
          I →
        OperatorRidgelet.IsRegularAlongRays
          (OperatorRidgelet.gaussianMixture N
            α)
          I
          (OperatorRidgelet.gaussFourier μ
            (OperatorRidgelet.layerObservable
              m a b
              OperatorRidgelet.gaussianFun φ))
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: consequently `F_Q F_φ` is regular along rays, for every band-pass `ρ`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_f.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ)
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b)
      (φ : Y)
      (F :
        ↥(OperatorRidgelet.spectralCore μ
            (OperatorRidgelet.gaussianMixture N α))) :
      ↑↑↑F =ᵐ[μ]
          OperatorRidgelet.layerObservable m a b
            OperatorRidgelet.gaussianFun φ →
        ∀
          (g :
            ↥(OperatorRidgelet.spectralCore μ
                (OperatorRidgelet.gaussianMixture N α))),
          (OperatorRidgelet.frameOperator μ
                (OperatorRidgelet.gaussianMixture N α)
                (OperatorRidgelet.spectralEmbed μ
                  (OperatorRidgelet.gaussianMixture N α) F))
              (OperatorRidgelet.spectralEmbed μ
                (OperatorRidgelet.gaussianMixture N α) g) =
            ∫ (x : H),
              OperatorRidgelet.spectralTarget
                  (OperatorRidgelet.gaussianMixture N α)
                  (OperatorRidgelet.gaussFourier μ
                    (OperatorRidgelet.layerObservable m a b
                      OperatorRidgelet.gaussianFun φ))
                  x *
                (starRingEnd ℂ) (↑↑↑g x) ∂μ
    theorem OperatorRidgelet.Paper.ex_7_6_ii_f.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y)
      (F :
        ↥(OperatorRidgelet.spectralCore μ
            (OperatorRidgelet.gaussianMixture
              N α))) :
      ↑↑↑F =ᵐ[μ]
          OperatorRidgelet.layerObservable m a
            b OperatorRidgelet.gaussianFun φ →
        ∀
          (g :
            ↥(OperatorRidgelet.spectralCore μ
                (OperatorRidgelet.gaussianMixture
                  N α))),
          (OperatorRidgelet.frameOperator μ
                (OperatorRidgelet.gaussianMixture
                  N α)
                (OperatorRidgelet.spectralEmbed
                  μ
                  (OperatorRidgelet.gaussianMixture
                    N α)
                  F))
              (OperatorRidgelet.spectralEmbed
                μ
                (OperatorRidgelet.gaussianMixture
                  N α)
                g) =
            ∫ (x : H),
              OperatorRidgelet.spectralTarget
                  (OperatorRidgelet.gaussianMixture
                    N α)
                  (OperatorRidgelet.gaussFourier
                    μ
                    (OperatorRidgelet.layerObservable
                      m a b
                      OperatorRidgelet.gaussianFun
                      φ))
                  x *
                (starRingEnd ℂ) (↑↑↑g x) ∂μ
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: the reconstruction formulas of Theorem `thm:4.8` hold for `F_φ`; in particular
    `T_α F_φ` is represented by `g_G`, `G = F_Q F_φ`: `T_α F_φ [g] = ∫ g_G(x) conj(g(x)) μ_Q(dx)`
    for `g ∈ 𝒟_α`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_g.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [MeasurableSpace H] {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      (μ : MeasureTheory.Measure H) [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (φ : Y) :
      OperatorRidgelet.ridgelet μ (⇑ρ)
          (OperatorRidgelet.layerObservable m a b
            OperatorRidgelet.gaussianFun φ) =
        OperatorRidgelet.coefficientFormula (⇑ρ)
          (OperatorRidgelet.gaussFourier μ
            (OperatorRidgelet.layerObservable m a b
              OperatorRidgelet.gaussianFun φ))
    theorem OperatorRidgelet.Paper.ex_7_6_ii_g.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y) :
      OperatorRidgelet.ridgelet μ (⇑ρ)
          (OperatorRidgelet.layerObservable m
            a b OperatorRidgelet.gaussianFun
            φ) =
        OperatorRidgelet.coefficientFormula
          (⇑ρ)
          (OperatorRidgelet.gaussFourier μ
            (OperatorRidgelet.layerObservable
              m a b
              OperatorRidgelet.gaussianFun φ))
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: the ridgelet coefficient of `F_φ` is the coefficient `γ_G` of `G = F_Q F_φ`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_h.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (φ : Y) :
      MeasureTheory.Integrable
        (fun p =>
          (1 + ‖p.1‖ ^ 2 + |p.2| ^ 2) *
            ‖OperatorRidgelet.ridgelet μ (⇑ρ)
                (OperatorRidgelet.layerObservable m a b
                  OperatorRidgelet.gaussianFun φ)
                p‖)
        (OperatorRidgelet.parameterMeasure
          (OperatorRidgelet.gaussianMixture N α))
    theorem OperatorRidgelet.Paper.ex_7_6_ii_h.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y) :
      MeasureTheory.Integrable
        (fun p =>
          (1 + ‖p.1‖ ^ 2 + |p.2| ^ 2) *
            ‖OperatorRidgelet.ridgelet μ (⇑ρ)
                (OperatorRidgelet.layerObservable
                  m a b
                  OperatorRidgelet.gaussianFun
                  φ)
                p‖)
        (OperatorRidgelet.parameterMeasure
          (OperatorRidgelet.gaussianMixture N
            α))
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: the coefficient measure `(R_ρ F_φ) λ_α` has finite total variation and moments,
    `∫ (1 + ‖a‖² + |c|²) |R_ρ F_φ(a,c)| λ_α(da,dc) < ∞`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_i.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (φ : Y)
      (β' : TemperedDistribution ℝ ℂ) (b' : ℝ → ℝ)
      (hβ' : OperatorRidgelet.IsTemperedFunction β' b') {L : NNReal}
      (hb' : LipschitzWith L b')
      (hb'p : ¬OperatorRidgelet.IsPolynomialFun b') :
      OperatorRidgelet.integralNetworkDensity (fun t => ↑(b' t))
          (OperatorRidgelet.parameterMeasure
            (OperatorRidgelet.gaussianMixture N α))
          (OperatorRidgelet.ridgelet μ (⇑ρ)
            (OperatorRidgelet.layerObservable m a b
              OperatorRidgelet.gaussianFun φ)) =
        fun x =>
        OperatorRidgelet.temperedAdmissibilityConst α β' ρ *
          OperatorRidgelet.spectralTarget
            (OperatorRidgelet.gaussianMixture N α)
            (OperatorRidgelet.gaussFourier μ
              (OperatorRidgelet.layerObservable m a b
                OperatorRidgelet.gaussianFun φ))
            x
    theorem OperatorRidgelet.Paper.ex_7_6_ii_i.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y) (β' : TemperedDistribution ℝ ℂ)
      (b' : ℝ → ℝ)
      (hβ' :
        OperatorRidgelet.IsTemperedFunction β'
          b')
      {L : NNReal} (hb' : LipschitzWith L b')
      (hb'p :
        ¬OperatorRidgelet.IsPolynomialFun
            b') :
      OperatorRidgelet.integralNetworkDensity
          (fun t => ↑(b' t))
          (OperatorRidgelet.parameterMeasure
            (OperatorRidgelet.gaussianMixture
              N α))
          (OperatorRidgelet.ridgelet μ (⇑ρ)
            (OperatorRidgelet.layerObservable
              m a b
              OperatorRidgelet.gaussianFun
              φ)) =
        fun x =>
        OperatorRidgelet.temperedAdmissibilityConst
            α β' ρ *
          OperatorRidgelet.spectralTarget
            (OperatorRidgelet.gaussianMixture
              N α)
            (OperatorRidgelet.gaussFourier μ
              (OperatorRidgelet.layerObservable
                m a b
                OperatorRidgelet.gaussianFun
                φ))
            x
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: the ridgelet coefficient `R_ρ F_φ` synthesizes, with any real Lipschitz
    non-polynomial `β'`, the target `C^{(α)}_{β',ρ} T_α F_φ` (represented by `g_G`). 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_j.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (φ : Y)
      (β' : TemperedDistribution ℝ ℂ) (b' : ℝ → ℝ)
      (hβ' : OperatorRidgelet.IsTemperedFunction β' b') {L : NNReal}
      (hb' : LipschitzWith L b')
      (hb'p : ¬OperatorRidgelet.IsPolynomialFun b') (K : Set H)
      (hK : IsCompact K) (n : ℕ) (hn : 0 < n) :
      ∫ (θ : Fin n → H × ℝ),
          OperatorRidgelet.compactSupNorm K fun x =>
            OperatorRidgelet.densitySampledNetwork (fun t => ↑(b' t))
                (OperatorRidgelet.parameterMeasure
                  (OperatorRidgelet.gaussianMixture N α))
                (OperatorRidgelet.ridgelet μ (⇑ρ)
                  (OperatorRidgelet.layerObservable m a b
                    OperatorRidgelet.gaussianFun φ))
                θ x -
              OperatorRidgelet.temperedAdmissibilityConst α β' ρ *
                OperatorRidgelet.spectralTarget
                  (OperatorRidgelet.gaussianMixture N α)
                  (OperatorRidgelet.gaussFourier μ
                    (OperatorRidgelet.layerObservable m a b
                      OperatorRidgelet.gaussianFun φ))
                  x ∂OperatorRidgelet.sampleLaw n
            (OperatorRidgelet.densityLaw
              (OperatorRidgelet.parameterMeasure
                (OperatorRidgelet.gaussianMixture N α))
              (OperatorRidgelet.ridgelet μ (⇑ρ)
                (OperatorRidgelet.layerObservable m a b
                  OperatorRidgelet.gaussianFun φ))) ≤
        8 *
              OperatorRidgelet.densityWeight
                (OperatorRidgelet.parameterMeasure
                  (OperatorRidgelet.gaussianMixture N α))
                (OperatorRidgelet.ridgelet μ (⇑ρ)
                  (OperatorRidgelet.layerObservable m a b
                    OperatorRidgelet.gaussianFun φ)) /
            √↑n *
          (|b' 0| +
            ↑L * OperatorRidgelet.compactRadius K *
              √(OperatorRidgelet.secondMoment
                  (OperatorRidgelet.densityLaw
                    (OperatorRidgelet.parameterMeasure
                      (OperatorRidgelet.gaussianMixture N α))
                    (OperatorRidgelet.ridgelet μ (⇑ρ)
                      (OperatorRidgelet.layerObservable m a b
                        OperatorRidgelet.gaussianFun φ)))))
    theorem OperatorRidgelet.Paper.ex_7_6_ii_j.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y) (β' : TemperedDistribution ℝ ℂ)
      (b' : ℝ → ℝ)
      (hβ' :
        OperatorRidgelet.IsTemperedFunction β'
          b')
      {L : NNReal} (hb' : LipschitzWith L b')
      (hb'p :
        ¬OperatorRidgelet.IsPolynomialFun b')
      (K : Set H) (hK : IsCompact K) (n : ℕ)
      (hn : 0 < n) :
      ∫ (θ : Fin n → H × ℝ),
          OperatorRidgelet.compactSupNorm K
            fun x =>
            OperatorRidgelet.densitySampledNetwork
                (fun t => ↑(b' t))
                (OperatorRidgelet.parameterMeasure
                  (OperatorRidgelet.gaussianMixture
                    N α))
                (OperatorRidgelet.ridgelet μ
                  (⇑ρ)
                  (OperatorRidgelet.layerObservable
                    m a b
                    OperatorRidgelet.gaussianFun
                    φ))
                θ x -
              OperatorRidgelet.temperedAdmissibilityConst
                  α β' ρ *
                OperatorRidgelet.spectralTarget
                  (OperatorRidgelet.gaussianMixture
                    N α)
                  (OperatorRidgelet.gaussFourier
                    μ
                    (OperatorRidgelet.layerObservable
                      m a b
                      OperatorRidgelet.gaussianFun
                      φ))
                  x ∂OperatorRidgelet.sampleLaw
            n
            (OperatorRidgelet.densityLaw
              (OperatorRidgelet.parameterMeasure
                (OperatorRidgelet.gaussianMixture
                  N α))
              (OperatorRidgelet.ridgelet μ
                (⇑ρ)
                (OperatorRidgelet.layerObservable
                  m a b
                  OperatorRidgelet.gaussianFun
                  φ))) ≤
        8 *
              OperatorRidgelet.densityWeight
                (OperatorRidgelet.parameterMeasure
                  (OperatorRidgelet.gaussianMixture
                    N α))
                (OperatorRidgelet.ridgelet μ
                  (⇑ρ)
                  (OperatorRidgelet.layerObservable
                    m a b
                    OperatorRidgelet.gaussianFun
                    φ)) /
            √↑n *
          (|b' 0| +
            ↑L *
                OperatorRidgelet.compactRadius
                  K *
              √(OperatorRidgelet.secondMoment
                  (OperatorRidgelet.densityLaw
                    (OperatorRidgelet.parameterMeasure
                      (OperatorRidgelet.gaussianMixture
                        N α))
                    (OperatorRidgelet.ridgelet
                      μ (⇑ρ)
                      (OperatorRidgelet.layerObservable
                        m a b
                        OperatorRidgelet.gaussianFun
                        φ)))))
    **Example [ex:7.6]** Neural-operator layer as an integral network.  Gaussian
    activation: the sampled network `eq:polar-network` of `R_ρ F_φ λ_α` with a real Lipschitz
    non-polynomial `β'` (with `V = ‖R_ρ F_φ‖_{L¹(λ_α)}` and samples from `p = |R_ρ F_φ| λ_α / V`,
    as in Theorem `thm:6.6`(iv)) converges to `C^{(α)}_{β',ρ} g_G` at the finite-width rate of
    `eq:spectral-barron`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_k.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ)
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b) :
      OperatorRidgelet.MemSpectralCoreVec μ
        (OperatorRidgelet.gaussianMixture N α)
        (OperatorRidgelet.operatorLayer m a b OperatorRidgelet.gaussianFun)
    theorem OperatorRidgelet.Paper.ex_7_6_ii_k.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b) :
      OperatorRidgelet.MemSpectralCoreVec μ
        (OperatorRidgelet.gaussianMixture N α)
        (OperatorRidgelet.operatorLayer m a b
          OperatorRidgelet.gaussianFun)
    **Example [ex:7.6]** Neural-operator layer as an integral network.  The same
    holds for `ℱ` itself as a `Y`-valued target: `ℱ ∈ 𝒟_α(Y)` for every `α > 0`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_l.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [MeasurableSpace H] {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      (μ : MeasureTheory.Measure H) [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ)
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b)
      (ξ : H) :
      OperatorRidgelet.gaussFourierVec μ
          (OperatorRidgelet.operatorLayer m a b
            OperatorRidgelet.gaussianFun)
          ξ =
        ∫ (y : Ω),
          ↑((√(1 + inner ℝ (Q (a y)) (a y)))⁻¹ *
                Real.exp
                  (-inner ℝ ((OperatorRidgelet.layerCovariance Q a y) ξ) ξ /
                    2)) •
            b y ∂m
    theorem OperatorRidgelet.Paper.ex_7_6_ii_l.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (ξ : H) :
      OperatorRidgelet.gaussFourierVec μ
          (OperatorRidgelet.operatorLayer m a
            b OperatorRidgelet.gaussianFun)
          ξ =
        ∫ (y : Ω),
          ↑((√(1 +
                      inner ℝ (Q (a y))
                        (a y)))⁻¹ *
                Real.exp
                  (-inner ℝ
                        ((OperatorRidgelet.layerCovariance
                            Q a y)
                          ξ)
                        ξ /
                    2)) •
            b y ∂m
    **Example [ex:7.6]** Neural-operator layer as an integral network.  The same
    holds for `ℱ` itself as a `Y`-valued target:
    `F_Q ℱ(ξ) = ∫ (1+σ_y²)^{-1/2} e^{-⟨S_yξ,ξ⟩/2} b_y m(dy)`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_m.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (I : Set ℝ) :
      OperatorRidgelet.IsFrequencyWindow (⇑ρ) I →
        OperatorRidgelet.IsRegularAlongRays
          (OperatorRidgelet.gaussianMixture N α) I
          (OperatorRidgelet.gaussFourierVec μ
            (OperatorRidgelet.operatorLayer m a b
              OperatorRidgelet.gaussianFun))
    theorem OperatorRidgelet.Paper.ex_7_6_ii_m.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (I : Set ℝ) :
      OperatorRidgelet.IsFrequencyWindow (⇑ρ)
          I →
        OperatorRidgelet.IsRegularAlongRays
          (OperatorRidgelet.gaussianMixture N
            α)
          I
          (OperatorRidgelet.gaussFourierVec μ
            (OperatorRidgelet.operatorLayer m
              a b
              OperatorRidgelet.gaussianFun))
    **Example [ex:7.6]** Neural-operator layer as an integral network.  The same
    holds for `ℱ` itself as a `Y`-valued target: `F_Q ℱ` is regular along rays for every band-pass
    `ρ`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_n.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [MeasurableSpace H] {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      (μ : MeasureTheory.Measure H) [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) :
      OperatorRidgelet.ridgeletVec μ (⇑ρ)
          (OperatorRidgelet.operatorLayer m a b
            OperatorRidgelet.gaussianFun) =
        OperatorRidgelet.coefficientFormulaVec (⇑ρ)
          (OperatorRidgelet.gaussFourierVec μ
            (OperatorRidgelet.operatorLayer m a b
              OperatorRidgelet.gaussianFun))
    theorem OperatorRidgelet.Paper.ex_7_6_ii_n.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] {Q : H →L[ℝ] H}
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b) :
      OperatorRidgelet.ridgeletVec μ (⇑ρ)
          (OperatorRidgelet.operatorLayer m a
            b OperatorRidgelet.gaussianFun) =
        OperatorRidgelet.coefficientFormulaVec
          (⇑ρ)
          (OperatorRidgelet.gaussFourierVec μ
            (OperatorRidgelet.operatorLayer m
              a b
              OperatorRidgelet.gaussianFun))
    **Example [ex:7.6]** Neural-operator layer as an integral network.  The same
    holds for `ℱ` itself as a `Y`-valued target: `R_ρ ℱ = γ_{F_Q ℱ}` for every band-pass `ρ`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_o.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) :
      MeasureTheory.Integrable
        (fun p =>
          (1 + ‖p.1‖ ^ 2 + |p.2| ^ 2) *
            ‖OperatorRidgelet.ridgeletVec μ (⇑ρ)
                (OperatorRidgelet.operatorLayer m a b
                  OperatorRidgelet.gaussianFun)
                p‖)
        (OperatorRidgelet.parameterMeasure
          (OperatorRidgelet.gaussianMixture N α))
    theorem OperatorRidgelet.Paper.ex_7_6_ii_o.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b) :
      MeasureTheory.Integrable
        (fun p =>
          (1 + ‖p.1‖ ^ 2 + |p.2| ^ 2) *
            ‖OperatorRidgelet.ridgeletVec μ
                (⇑ρ)
                (OperatorRidgelet.operatorLayer
                  m a b
                  OperatorRidgelet.gaussianFun)
                p‖)
        (OperatorRidgelet.parameterMeasure
          (OperatorRidgelet.gaussianMixture N
            α))
    **Example [ex:7.6]** Neural-operator layer as an integral network.  The same
    holds for `ℱ` itself as a `Y`-valued target: the coefficient measure `(R_ρ ℱ) λ_α` has finite
    total variation and moments. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_ii_p.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [CompleteSpace H]
      [SecondCountableTopology H] [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] [SecondCountableTopology Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (hH : ¬FiniteDimensional ℝ H) {P Q : H →L[ℝ] H}
      (hP : OperatorRidgelet.IsTraceClassCovariance P)
      (hQ : OperatorRidgelet.IsTraceClassCovariance Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN : OperatorRidgelet.IsCenteredGaussianLayers P N) {α : ℝ}
      (hα : 0 < α) (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ : OperatorRidgelet.IsCenteredGaussian Q μ) (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ) (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b)
      (β' : TemperedDistribution ℝ ℂ) (b' : ℝ → ℝ)
      (hβ' : OperatorRidgelet.IsTemperedFunction β' b') {L : NNReal}
      (hb' : LipschitzWith L b')
      (hb'p : ¬OperatorRidgelet.IsPolynomialFun b') :
      OperatorRidgelet.integralNetworkDensity (fun t => ↑(b' t))
          (OperatorRidgelet.parameterMeasure
            (OperatorRidgelet.gaussianMixture N α))
          (OperatorRidgelet.ridgeletVec μ (⇑ρ)
            (OperatorRidgelet.operatorLayer m a b
              OperatorRidgelet.gaussianFun)) =
        fun x =>
        OperatorRidgelet.temperedAdmissibilityConst α β' ρ •
          OperatorRidgelet.spectralTarget
            (OperatorRidgelet.gaussianMixture N α)
            (OperatorRidgelet.gaussFourierVec μ
              (OperatorRidgelet.operatorLayer m a b
                OperatorRidgelet.gaussianFun))
            x
    theorem OperatorRidgelet.Paper.ex_7_6_ii_p.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [CompleteSpace H]
      [SecondCountableTopology H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y]
      [SecondCountableTopology Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (hH : ¬FiniteDimensional ℝ H)
      {P Q : H →L[ℝ] H}
      (hP :
        OperatorRidgelet.IsTraceClassCovariance
          P)
      (hQ :
        OperatorRidgelet.IsTraceClassCovariance
          Q)
      {N : ℝ → MeasureTheory.Measure H}
      (hN :
        OperatorRidgelet.IsCenteredGaussianLayers
          P N)
      {α : ℝ} (hα : 0 < α)
      (μ : MeasureTheory.Measure H)
      [MeasureTheory.IsProbabilityMeasure μ]
      (hμ :
        OperatorRidgelet.IsCenteredGaussian Q
          μ)
      (ρ : SchwartzMap ℝ ℝ)
      (hρ : OperatorRidgelet.IsBandPass ρ)
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (β' : TemperedDistribution ℝ ℂ)
      (b' : ℝ → ℝ)
      (hβ' :
        OperatorRidgelet.IsTemperedFunction β'
          b')
      {L : NNReal} (hb' : LipschitzWith L b')
      (hb'p :
        ¬OperatorRidgelet.IsPolynomialFun
            b') :
      OperatorRidgelet.integralNetworkDensity
          (fun t => ↑(b' t))
          (OperatorRidgelet.parameterMeasure
            (OperatorRidgelet.gaussianMixture
              N α))
          (OperatorRidgelet.ridgeletVec μ (⇑ρ)
            (OperatorRidgelet.operatorLayer m
              a b
              OperatorRidgelet.gaussianFun)) =
        fun x =>
        OperatorRidgelet.temperedAdmissibilityConst
            α β' ρ •
          OperatorRidgelet.spectralTarget
            (OperatorRidgelet.gaussianMixture
              N α)
            (OperatorRidgelet.gaussFourierVec
              μ
              (OperatorRidgelet.operatorLayer
                m a b
                OperatorRidgelet.gaussianFun))
            x
    **Example [ex:7.6]** Neural-operator layer as an integral network.  The same
    holds for `ℱ` itself as a `Y`-valued target: `R_ρ ℱ` synthesizes, with any real Lipschitz
    non-polynomial `β'`, the `Y`-valued target `C^{(α)}_{β',ρ} g_{F_Q ℱ}`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_iii_a.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b)
      (x : H) :
      OperatorRidgelet.operatorLayer m a b OperatorRidgelet.gaussianFun x =
        ∫ (p : Ω × ℝ),
          ↑(OperatorRidgelet.gaussianActDeriv2 p.2 *
                LeanRidgelet.relu (inner ℝ (a p.1) x - p.2)) •
            b p.1 ∂m.prod MeasureTheory.volume
    theorem OperatorRidgelet.Paper.ex_7_6_iii_a.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [MeasurableSpace H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (x : H) :
      OperatorRidgelet.operatorLayer m a b
          OperatorRidgelet.gaussianFun x =
        ∫ (p : Ω × ℝ),
          ↑(OperatorRidgelet.gaussianActDeriv2
                  p.2 *
                LeanRidgelet.relu
                  (inner ℝ (a p.1) x - p.2)) •
            b p.1 ∂m.prod MeasureTheory.volume
    **Example [ex:7.6]** Neural-operator layer as an integral network.  ReLU form:
    by `eq:gaussian-parameter-closed-forms`, the Gaussian-activation layer is
    `ℱ(x) = ∫∫ b_y φ''(b) ReLU(⟨a_y,x⟩ - b) m(dy) db`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_iii_b.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [MeasurableSpace H]
      [BorelSpace H] {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) :
      OperatorRidgelet.operatorLayer m a b OperatorRidgelet.gaussianFun =
        OperatorRidgelet.integralNetwork (fun t => ↑(LeanRidgelet.relu t))
          (OperatorRidgelet.layerHingeMeasure m a b)
    theorem OperatorRidgelet.Paper.ex_7_6_iii_b.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [MeasurableSpace H] [BorelSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b) :
      OperatorRidgelet.operatorLayer m a b
          OperatorRidgelet.gaussianFun =
        OperatorRidgelet.integralNetwork
          (fun t => ↑(LeanRidgelet.relu t))
          (OperatorRidgelet.layerHingeMeasure
            m a b)
    **Example [ex:7.6]** Neural-operator layer as an integral network.  ReLU form:
    the Gaussian-activation layer is the ReLU network with the coefficient measure
    `(y,b) ↦ (a_y, -b)`-pushforward of `φ''(b) b_y m(dy) db`. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_iii_c.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b) :
      MeasureTheory.IsFiniteMeasure
        (OperatorRidgelet.layerHingeMeasure m a b).variation
    theorem OperatorRidgelet.Paper.ex_7_6_iii_c.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [MeasurableSpace H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b) :
      MeasureTheory.IsFiniteMeasure
        (OperatorRidgelet.layerHingeMeasure m
            a b).variation
    **Example [ex:7.6]** Neural-operator layer as an integral network.  ReLU form:
    the ReLU coefficient measure is finite. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_iii_d.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] [MeasurableSpace H]
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω) [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y) (hL : OperatorRidgelet.IsLayerData m a b)
      (k : ℕ) :
      ∫⁻ (θ : H × ℝ),
          ENNReal.ofReal
            ((1 + ‖θ.1‖ + |θ.2|) ^
              k) ∂(OperatorRidgelet.layerHingeMeasure m a b).variation <
        ⊤
    theorem OperatorRidgelet.Paper.ex_7_6_iii_d.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H]
      [MeasurableSpace H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (k : ℕ) :
      ∫⁻ (θ : H × ℝ),
          ENNReal.ofReal
            ((1 + ‖θ.1‖ + |θ.2|) ^
              k) ∂(OperatorRidgelet.layerHingeMeasure
              m a b).variation <
        ⊤
    **Example [ex:7.6]** Neural-operator layer as an integral network.  ReLU form:
    the ReLU coefficient measure has all moments finite. 
  • complete
    theorem OperatorRidgelet.Paper.ex_7_6_iv.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] {Y : Type u_2}
      [NormedAddCommGroup Y] [InnerProductSpace ℂ Y] [CompleteSpace Y]
      {Ω : Type u_3} [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m] (a : Ω → H) (b : Ω → Y)
      (hL : OperatorRidgelet.IsLayerData m a b) (φ : Y)
      (hA : OperatorRidgelet.HasInfiniteRank (OperatorRidgelet.layerA m a))
      (hw :
        ∀ᵐ (y : Ω) ∂m,
          0 < (OperatorRidgelet.layerWeight b φ y).re ∧
            (OperatorRidgelet.layerWeight b φ y).im = 0) :
      ¬OperatorRidgelet.IsCylindrical
          (OperatorRidgelet.layerObservable m a b
            OperatorRidgelet.gaussianFun φ)
    theorem OperatorRidgelet.Paper.ex_7_6_iv.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y]
      [CompleteSpace Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      [MeasureTheory.IsFiniteMeasure m]
      (a : Ω → H) (b : Ω → Y)
      (hL :
        OperatorRidgelet.IsLayerData m a b)
      (φ : Y)
      (hA :
        OperatorRidgelet.HasInfiniteRank
          (OperatorRidgelet.layerA m a))
      (hw :
        ∀ᵐ (y : Ω) ∂m,
          0 <
              (OperatorRidgelet.layerWeight b
                  φ y).re ∧
            (OperatorRidgelet.layerWeight b φ
                  y).im =
              0) :
      ¬OperatorRidgelet.IsCylindrical
          (OperatorRidgelet.layerObservable m
            a b OperatorRidgelet.gaussianFun
            φ)
    **Example [ex:7.6]** Neural-operator layer as an integral network.
    Non-cylindricity: if `A` has infinite rank, `β = Φ`, and `w_φ > 0` `m`-almost everywhere, then
    `F_φ` is not cylindrical. 
  • complete
    def OperatorRidgelet.HasPolynomialGrowth (β : ℝ → ℝ) : Prop
    def OperatorRidgelet.HasPolynomialGrowth
      (β : ℝ → ℝ) : Prop
    `β : ℝ → ℝ` has polynomial growth: `|β(t)| ≤ C (1 + |t|)^p` for some constants `C`, `p`. 
  • structure(4 fields)defined in OperatorRidgelet/Examples/Defs.lean
    complete
    structure OperatorRidgelet.IsLayerData.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] {Y : Type u_2} [NormedAddCommGroup Y]
      {Ω : Type u_3} [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω)
      (a : Ω → H) (b : Ω → Y) : Prop
    structure OperatorRidgelet.IsLayerData.{u_1, u_2,
        u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      {Y : Type u_2} [NormedAddCommGroup Y]
      {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      (a : Ω → H) (b : Ω → Y) : Prop
    The standing hypotheses of the neural-operator layer: `y ↦ a_y ∈ H` is Borel and bounded,
    `y ↦ b_y ∈ Y` is Borel with `∫ ‖b_y‖ m(dy) < ∞`. 
    stronglyMeasurable_a : MeasureTheory.StronglyMeasurable a
    `y ↦ a_y` is Borel. 
    bounded_a : ∃ C, ∀ (y : Ω), ‖a y‖ ≤ C
    `y ↦ a_y` is bounded. 
    stronglyMeasurable_b : MeasureTheory.StronglyMeasurable b
    `y ↦ b_y` is Borel. 
    integrable_b : MeasureTheory.Integrable b m
    `∫ ‖b_y‖ m(dy) < ∞`. 
  • complete
    def OperatorRidgelet.layerSupNorm.{u_1, u_3} {H : Type u_1}
      [NormedAddCommGroup H] {Ω : Type u_3} (a : Ω → H) : ℝ
    def OperatorRidgelet.layerSupNorm.{u_1, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      {Ω : Type u_3} (a : Ω → H) : ℝ
    `‖A‖_∞ = sup_y ‖a_y‖`, the supremum over the parameter space `Ω` of the layer (junk `0` if
    unbounded).  This is a genuinely different notion from the compact-open norm `compactSupNorm K`
    of `OperatorRidgelet.Sampling.Defs`, which is a supremum over a set of inputs `x ∈ K`. 
  • complete
    def OperatorRidgelet.operatorLayer.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] {Y : Type u_2}
      [NormedAddCommGroup Y] [InnerProductSpace ℂ Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω) (a : Ω → H)
      (b : Ω → Y) (β : ℝ → ℝ) (x : H) : Y
    def OperatorRidgelet.operatorLayer.{u_1, u_2,
        u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      (a : Ω → H) (b : Ω → Y) (β : ℝ → ℝ)
      (x : H) : Y
    The neural-operator layer `ℱ(x) = B β(Ax) = ∫ β(⟨a_y,x⟩) b_y m(dy)` (`eq:operator-layer`). 
  • complete
    def OperatorRidgelet.layerWeight.{u_2, u_3} {Y : Type u_2}
      [NormedAddCommGroup Y] [InnerProductSpace ℂ Y] {Ω : Type u_3}
      (b : Ω → Y) (φ : Y) (y : Ω) : ℂ
    def OperatorRidgelet.layerWeight.{u_2, u_3}
      {Y : Type u_2} [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] {Ω : Type u_3}
      (b : Ω → Y) (φ : Y) (y : Ω) : ℂ
    The weight `w_φ(y) = ⟨b_y, φ⟩_Y` of the scalar observable. 
  • complete
    def OperatorRidgelet.layerObservable.{u_1, u_2, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] {Y : Type u_2}
      [NormedAddCommGroup Y] [InnerProductSpace ℂ Y] {Ω : Type u_3}
      [MeasurableSpace Ω] (m : MeasureTheory.Measure Ω) (a : Ω → H)
      (b : Ω → Y) (β : ℝ → ℝ) (φ : Y) (x : H) : ℂ
    def OperatorRidgelet.layerObservable.{u_1,
        u_2, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H] {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      (a : Ω → H) (b : Ω → Y) (β : ℝ → ℝ)
      (φ : Y) (x : H) : ℂ
    The scalar observable `F_φ(x) = ⟨ℱ(x), φ⟩_Y` of the layer. 
  • complete
    def OperatorRidgelet.layerA.{u_1, u_3} {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H] {Ω : Type u_3} [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω) (a : Ω → H) : H →ₗ[ℝ] Ω →ₘ[m] ℝ
    def OperatorRidgelet.layerA.{u_1, u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H] {Ω : Type u_3}
      [MeasurableSpace Ω]
      (m : MeasureTheory.Measure Ω)
      (a : Ω → H) : H →ₗ[ℝ] Ω →ₘ[m] ℝ
    The operator `A : H → L²(m)`, `(Ax)(y) = ⟨a_y, x⟩`, as a linear map into the a.e.-classes
    `Ω →ₘ[m] ℝ` (`0` if `a` is not measurable). 
  • complete
    def OperatorRidgelet.layerCovariance.{u_1, u_3} {H : Type u_1}
      [NormedAddCommGroup H] [InnerProductSpace ℝ H] {Ω : Type u_3}
      (Q : H →L[ℝ] H) (a : Ω → H) (y : Ω) : H →L[ℝ] H
    def OperatorRidgelet.layerCovariance.{u_1,
        u_3}
      {H : Type u_1} [NormedAddCommGroup H]
      [InnerProductSpace ℝ H] {Ω : Type u_3}
      (Q : H →L[ℝ] H) (a : Ω → H) (y : Ω) :
      H →L[ℝ] H
    The covariance `S_y = Q - (1 + σ_y²)⁻¹ (Qa_y) ⊗ (Qa_y)`, `σ_y² = ⟨Qa_y, a_y⟩`, of
    Example `ex:7.6`(ii). 
  • complete
    def OperatorRidgelet.layerMeasure.{u_1, u_2, u_3} {H : Type u_1}
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      {Ω : Type u_3} [MeasurableSpace Ω] [MeasurableSpace H]
      (m : MeasureTheory.Measure Ω) (a : Ω → H) (b : Ω → Y) :
      MeasureTheory.VectorMeasure (H × ℝ) Y
    def OperatorRidgelet.layerMeasure.{u_1, u_2,
        u_3}
      {H : Type u_1} {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] {Ω : Type u_3}
      [MeasurableSpace Ω] [MeasurableSpace H]
      (m : MeasureTheory.Measure Ω)
      (a : Ω → H) (b : Ω → Y) :
      MeasureTheory.VectorMeasure (H × ℝ) Y
    The `Y`-valued coefficient measure `Γ = ι_#(b_y m(dy))`, `ι(y) = (a_y, 0)`, of the layer. 
  • complete
    def OperatorRidgelet.layerHingeMeasure.{u_1, u_2, u_3} {H : Type u_1}
      {Y : Type u_2} [NormedAddCommGroup Y] [InnerProductSpace ℂ Y]
      {Ω : Type u_3} [MeasurableSpace Ω] [MeasurableSpace H]
      (m : MeasureTheory.Measure Ω) (a : Ω → H) (b : Ω → Y) :
      MeasureTheory.VectorMeasure (H × ℝ) Y
    def OperatorRidgelet.layerHingeMeasure.{u_1,
        u_2, u_3}
      {H : Type u_1} {Y : Type u_2}
      [NormedAddCommGroup Y]
      [InnerProductSpace ℂ Y] {Ω : Type u_3}
      [MeasurableSpace Ω] [MeasurableSpace H]
      (m : MeasureTheory.Measure Ω)
      (a : Ω → H) (b : Ω → Y) :
      MeasureTheory.VectorMeasure (H × ℝ) Y
    The coefficient measure of the ReLU form of the Gaussian-activation layer: the pushforward
    of `φ''(b) b_y m(dy) db` under `(y, b) ↦ (a_y, -b)`. 
Proof for Example 7.6
Proof uses 7
Proof dependency previews
Preview
Lemma 3.5
Loading preview
Proof dependency preview content is loaded from the rendered-fragment cache.

Part (i) is the change of variables for the pushforward measure and \|\iota(y)\|^2\le\|A\|_\infty^2. For (ii), the pair (\langle a_y,x\rangle,\langle x,\xi\rangle) is centred Gaussian under \mu_Q and \mathbb E[e^{-Z^2/2}e^{-iW}]=(1+\sigma^2)^{-1/2}\exp(-\tau^2/2+r^2/(2(1+\sigma^2))); Cauchy–Schwarz gives the lower bound on S_y, Lemma 4.4 (a) and (c) give the condition in Definition 4.2, and Theorem 4.8, Theorem 6.6, and Theorem 4.11 give the rest. Part (iii) is Fubini with Lemma 7.3; for (iv), a vector x\in\ker L\setminus\ker A gives F_\varphi(tx)=F_\varphi(0) for all t, while dominated convergence gives F_\varphi(tx)\to\int w_\varphi\mathbf 1_{\{Ax=0\}}\mathrm dm<F_\varphi(0).

Remark 7.7 (Equivariance of the transform).

If a unitary U satisfies UQU^*=Q, then the Gaussian input law is invariant and R_\rho[f\circ U](a,b)=R_\rho f(Ua,b). If also UPU^*=P, the direction and parameter measures are invariant and the Plancherel and reconstruction formulas commute with this action. On L^2(\mathbb R^d), a translation-invariant Gaussian input law with injective trace-class covariance is unavailable. The Gaussian weight therefore breaks translation invariance there; the operator-layer network identity itself does not use that input weight.