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ASTIS mathematical exposition

Actual normalized reference and returned sampling precision

AutoSamplingTheory.ExampleCases.SmoothedPicardHMC.NormalizedReferenceCall.normalized_reference_call · theorem · Teaching coverage

Statement

N and p->S(out(p)) are measurable. For every p, the actual output satisfies norm(grad F_p(out))^2<=a*d and every earlier iterate strictly fails that threshold. The scaled reference satisfies norm(grad G_p(S(out)))^2<=d/k. G_p is C2 with genuine Hessian bounds [a/c,1]. Both exponential Gibbs weights are integrable with strictly positive integrals, and both tilted laws are probability measures. S#pi_p=pibar_p and grad G_p(S(x))=c^(-1/2)*grad F_p(x). For every next variance t>=0, R#H(pibar_p,sqrt(t))=H(pi_p,sqrt(t/c)). For every actual probability nubar and t,B>=0, a supplied W2(nubar,H(pibar_p,sqrt(t)))^2<=ofReal(B) implies W2(R#nubar,H(pi_p,sqrt(t/c)))^2<=ofReal(B/c).

\[\|\nabla G_p(S\,\mathrm{out}(p))\|^2\le d/k,\quad S_\#\pi_p=\bar\pi_p,\quad R_\#H(\bar\pi_p,\sqrt t)=H(\pi_p,\sqrt{t/c}),\quad W_2^2\le B/c.\]

All objects and hypotheses

  • E is a complete finite-dimensional real inner-product space with its Borel measurable structure and canonical volume; d=dim(E)>0. U is C2 and its genuine Hessian lies between alpha*norm(v)^2 and beta*norm(v)^2 for every x,v, with 0<alpha<=beta.
  • eta>=0,tau>0,r>=0. The actual probability nu satisfies W2(nu,law(X+sqrt(eta)*Z))^2<=ofReal(r^2), where X has the normalized Gibbs law volume.tilted(-U) and Z is an independent standard Gaussian. This is the outer input to the existing actual reference construction.
  • A=eta+tau,a=alpha+1/A,c=beta+1/A,k=c/a. For p=(y,z), u(p)=y+sqrt(tau)*z and F_p(x)=U(x)+norm(x-u(p))^2/(2*A). Here a is a curvature lower bound, not an RGO variance.
  • T_p(x)=x-c^(-1)*grad F_p(x). N(p) is the least n with norm(grad F_p(T_p^n(y)))^2<=a*d if such an n exists, otherwise zero; out(p)=T_p^N(p)(y). The inherited finite-hit proof eliminates the default branch.
  • S(x)=sqrt(c)*x,R(x)=x/sqrt(c),G_p(x)=F_p(R(x)). pi_p=volume.tilted(-F_p) and pibar_p=volume.tilted(-G_p). Write H(mu,sigma)=law(X+sigma*Z) for independent X~mu,Z~stdGaussian(E). W2 squared is the extended nonnegative infimum of quadratic coupling costs.

Mathematical proof

1. Retain the actual first-hit program and pair dependence

The parent JointReferenceGradientDescent theorem is applied to the same U,eta,tau and actual outer input law. actualIndex is definitionally the same first ad-hit program. Thus N and out are measurable, the stopped gradient satisfies the threshold, and every earlier iterate fails it. Continuous S preserves output measurability. No supplied reference point replaces the program.

\[N(p)=\min\{n:\|\nabla F_p(T_p^n(p_1))\|^2\le ad\},\qquad p\mapsto S(\mathrm{out}(p))\text{ is measurable}.\]
Corresponding Lean step

actualIndex; normalized_reference_call: hP,hNm,hom,hp,hearly

2. Differentiate the actual regularized potential

Differentiate the quadratic norm term twice. Its first derivative is A^(-1) inner(x-u,.) and its second derivative is A^(-1) inner(.,.). Adding these genuine derivatives to those of U shifts both Hessian bounds by A^(-1); no independent Hessian field is assumed.

\[D^2F_p(x)[v,v]=D^2U(x)[v,v]+A^{-1}\|v\|^2,\qquad a\|v\|^2\le D^2F_p(x)[v,v]\le c\|v\|^2.\]
Corresponding Lean step

regularized_hessian: hq,hfd,hdd; normalized_reference_call: hreg,hFH

3. Apply the chain rule and certify the scaled reference

For any real scalar s, differentiating F(s*x) gives s times its gradient and s^2 times its Hessian quadratic form. Set s=1/sqrt(c), using c>0. The actual stopped threshold ad becomes ad/c=d/k. The same chain rule gives normalized curvature [a/c,1].

\[\nabla G_p(Sx)=c^{-1/2}\nabla F_p(x),\quad D^2G_p(x)[v,v]=c^{-1}D^2F_p(Rx)[v,v],\quad ad/c=d/k.\]
Corresponding Lean step

differential_scaling; normalized_laws: hD,hGH; normalized_reference_call: hi,hb

4. Prove both Gibbs normalizations before identifying probability laws

Positive Hessian lower bounds imply strong convexity of F and G. StrongConvexGibbsIntegrability supplies integrability of their actual exponential weights without a minimizer assumption. Positive exponential integrals then give nonzero finite normalizers and actual probability tilted measures.

\[0<Z_F=\int e^{-F(x)}\,dx<\infty,\qquad 0<Z_G=\int e^{-G(x)}\,dx<\infty.\]
Corresponding Lean step

normalized_laws: hI,hIG; HessianStrongConvexity.strongConvexOn_univ_of_fderiv2_lower; integral_exp_pos; isProbabilityMeasure_tilted

5. Cancel the same volume Jacobian in numerator and denominator

For s=sqrt(c)>0, the volume substitution has J=abs((s^d)^(-1))>0. On each measurable B it gives I_F(S^(-1)B)=J*I_G(B), and also Z_F=J*Z_G. The tilted setwise formula cancels J, proving S#pi_F=pi_G. The private identity also supports total-integral degenerate inputs; the actual public consumer separately proves true positive normalization.

\[(S_\#\pi_F)(B)=\frac{J\int_B e^{-G(x)}dx}{JZ_G}=\pi_G(B),\qquad J=c^{-d/2}.\]
Corresponding Lean step

scaled_gibbs: hJ,hZ,hI; Measure.integral_comp_smul; tilted_apply_eq_ofReal_integral'

6. Transform the actual independent Gaussian product law

Expand H(mu,sigma) as the pushforward of mu.prod(stdGaussian) by (x,z)->x+sigma*z. Product-map and map-composition identities show R(SX+sqrt(t)Z)=X+sqrt(t/c)Z. The next t is distinct from the current eta and tau; t=0 is included.

\[R_\#H(S_\#\pi,\sqrt t)=H(\pi,c^{-1/2}\sqrt t)=H(\pi,\sqrt{t/c}).\]
Corresponding Lean step

scaled_smoothing: law,hp; normalized_laws: hsm; Measure.map_prod_map; Measure.map_map; Real.sqrt_div

7. Push each coupling and take the cost infimum

For any coupling gamma, map the pair by (x,y)->(s*x,s*y). Its two marginals are exactly the scaled marginals, and its quadratic cost is s^2 times the original cost. Since ofReal(s^2) is positive and finite for nonzero s, it commutes with both indexed infima defining transport cost, even for infinite cost or an empty coupling set. No optimal coupling or separate second-moment assumption is used.

\[\int\|sx-sy\|^2d\gamma=s^2\int\|x-y\|^2d\gamma,\quad W_2^2(s_\#\mu,s_\#\nu)\le s^2W_2^2(\mu,\nu).\]
Corresponding Lean step

scaled_wasserstein: hcouple,hcost; ENNReal.mul_iInf_of_ne; Transport.transportCost_le_lintegral_of_isCoupling

8. Propagate the supplied next-call precision

Apply the coupling bound with s=1/sqrt(c), substitute the proved smoothing-law identity, and use the nonnegative supplied budget B. This yields actual returned squared precision B/c. The source choice B=k*epsilon^2 therefore returns epsilon^2/a. This step consumes the normalized sampler guarantee; constructing that sampler and propagating conditional histories and total costs remain separate.

\[W_2^2(\bar\nu,H(\bar\pi,\sqrt t))\le B\Longrightarrow W_2^2(R_\#\bar\nu,H(\pi,\sqrt{t/c}))\le B/c;\quad \frac{k\varepsilon^2}{c}=\frac{\varepsilon^2}{a}.\]
Corresponding Lean step

normalized_laws: hprec; normalized_reference_call: hprec

Lean statement · normalized_reference_call

Actual first-hit reference normalization,genuine Hessian,positive Gibbs laws,Gaussian variance and returned Wasserstein precision.

Braces mark parameters Lean can infer; square brackets request structures such as a measurable space or probability measure. Named hypotheses are mathematical premises, not facts established by this declaration. Section parameters are described in the mathematical hypotheses above; the module link retains their exact source context.

theorem normalized_reference_call [FiniteDimensional ℝ E]
    [MeasurableSpace E] [BorelSpace E] {U : E → ℝ} {α β : ℝ≥0}
    (hα : 0 < α) (hαβ : α ≤ β) (hU : ContDiff ℝ 2 U)
    (hH : ∀ x v : E, (α:ℝ)*‖v‖^2 ≤ fderiv ℝ (fderiv ℝ U) x v v ∧
      fderiv ℝ (fderiv ℝ U) x v v ≤ (β:ℝ)*‖v‖^2)
    {η τ r : ℝ} (hη : 0 ≤ η) (hτ : 0 < τ) (hr : 0 ≤ r)
    (hd : 0 < (Module.finrank ℝ E : ℝ))
    (ν : Measure E) [IsProbabilityMeasure ν]
    (hw : TechnicalLemmas.Measure.WassersteinSpace.wassersteinDistance ν
      (TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing
        ((volume : Measure E).tilted (fun x => -U x)) (Real.sqrt η)) ^ 2 ≤ ENNReal.ofReal (r^2)) :
    let d : ℝ := Module.finrank ℝ E
    let A := η+τ
    let a := (α:ℝ)+A⁻¹
    let c := (β:ℝ)+A⁻¹
    let k := c/a
    let u := fun p : E × E => p.1+Real.sqrt τ • p.2
    let F := fun p x => U x+A⁻¹/2*‖x-u p‖^2
    let T := fun p x => x-c⁻¹ • gradient (F p) x
    let N := actualIndex T (fun p x => ‖gradient (F p) x‖^2) (a*d)
    let out := fun p => (T p)^[N p] p.1
    let S := fun x : E => Real.sqrt c • x
    let R := fun x : E => (Real.sqrt c)⁻¹ • x
    let G := fun p x => F p (R x)
    let π := fun p => (volume : Measure E).tilted (fun x => -F p x)
    let πbar := fun p => (volume : Measure E).tilted (fun x => -G p x)
    Measurable N ∧ Measurable (fun p => S (out p)) ∧
    (∀ p, ‖gradient (F p) (out p)‖^2 ≤ a*d ∧
      (∀ j < N p, a*d < ‖gradient (F p) ((T p)^[j] p.1)‖^2) ∧
      ‖gradient (G p) (S (out p))‖^2 ≤ d/k ∧
      ContDiff ℝ 2 (G p) ∧
      (∀ x v, (a/c)*‖v‖^2 ≤ fderiv ℝ (fderiv ℝ (G p)) x v v ∧
        fderiv ℝ (fderiv ℝ (G p)) x v v ≤ ‖v‖^2) ∧
      Integrable (fun x => Real.exp (-F p x)) (volume : Measure E) ∧
      0 < ∫ x : E, Real.exp (-F p x) ∧ IsProbabilityMeasure (π p) ∧
      Integrable (fun x => Real.exp (-G p x)) (volume : Measure E) ∧
      0 < ∫ x : E, Real.exp (-G p x) ∧ IsProbabilityMeasure (πbar p) ∧
      (π p).map S = πbar p ∧
      (∀ x, gradient (G p) (S x) = (Real.sqrt c)⁻¹ • gradient (F p) x) ∧
      (∀ t : ℝ, 0 ≤ t →
        (TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing (πbar p) (Real.sqrt t)).map R =
          TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing (π p) (Real.sqrt (t/c))) ∧
      (∀ (νbar : Measure E) (t B : ℝ), IsProbabilityMeasure νbar → 0 ≤ t → 0 ≤ B →
        TechnicalLemmas.Measure.WassersteinSpace.wassersteinDistance νbar
          (TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing (πbar p) (Real.sqrt t)) ^ 2 ≤
            ENNReal.ofReal B →
        TechnicalLemmas.Measure.WassersteinSpace.wassersteinDistance (νbar.map R)
          (TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing (π p) (Real.sqrt (t/c))) ^ 2 ≤
            ENNReal.ofReal (B/c)))

Exact module and namespace context

Lean proof · normalized_reference_call

Chain rules,actual first-hit parent,positive strong-convex Gibbs normalization,Haar substitution,product maps,and arbitrary-coupling infimum scaling.

Braces mark parameters Lean can infer; square brackets request structures such as a measurable space or probability measure. Named hypotheses are mathematical premises, not facts established by this declaration. Section parameters are described in the mathematical hypotheses above; the module link retains their exact source context.

theorem normalized_reference_call [FiniteDimensional ℝ E]
    [MeasurableSpace E] [BorelSpace E] {U : E → ℝ} {α β : ℝ≥0}
    (hα : 0 < α) (hαβ : α ≤ β) (hU : ContDiff ℝ 2 U)
    (hH : ∀ x v : E, (α:ℝ)*‖v‖^2 ≤ fderiv ℝ (fderiv ℝ U) x v v ∧
      fderiv ℝ (fderiv ℝ U) x v v ≤ (β:ℝ)*‖v‖^2)
    {η τ r : ℝ} (hη : 0 ≤ η) (hτ : 0 < τ) (hr : 0 ≤ r)
    (hd : 0 < (Module.finrank ℝ E : ℝ))
    (ν : Measure E) [IsProbabilityMeasure ν]
    (hw : TechnicalLemmas.Measure.WassersteinSpace.wassersteinDistance ν
      (TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing
        ((volume : Measure E).tilted (fun x => -U x)) (Real.sqrt η)) ^ 2 ≤ ENNReal.ofReal (r^2)) :
    let d : ℝ := Module.finrank ℝ E
    let A := η+τ
    let a := (α:ℝ)+A⁻¹
    let c := (β:ℝ)+A⁻¹
    let k := c/a
    let u := fun p : E × E => p.1+Real.sqrt τ • p.2
    let F := fun p x => U x+A⁻¹/2*‖x-u p‖^2
    let T := fun p x => x-c⁻¹ • gradient (F p) x
    let N := actualIndex T (fun p x => ‖gradient (F p) x‖^2) (a*d)
    let out := fun p => (T p)^[N p] p.1
    let S := fun x : E => Real.sqrt c • x
    let R := fun x : E => (Real.sqrt c)⁻¹ • x
    let G := fun p x => F p (R x)
    let π := fun p => (volume : Measure E).tilted (fun x => -F p x)
    let πbar := fun p => (volume : Measure E).tilted (fun x => -G p x)
    Measurable N ∧ Measurable (fun p => S (out p)) ∧
    (∀ p, ‖gradient (F p) (out p)‖^2 ≤ a*d ∧
      (∀ j < N p, a*d < ‖gradient (F p) ((T p)^[j] p.1)‖^2) ∧
      ‖gradient (G p) (S (out p))‖^2 ≤ d/k ∧
      ContDiff ℝ 2 (G p) ∧
      (∀ x v, (a/c)*‖v‖^2 ≤ fderiv ℝ (fderiv ℝ (G p)) x v v ∧
        fderiv ℝ (fderiv ℝ (G p)) x v v ≤ ‖v‖^2) ∧
      Integrable (fun x => Real.exp (-F p x)) (volume : Measure E) ∧
      0 < ∫ x : E, Real.exp (-F p x) ∧ IsProbabilityMeasure (π p) ∧
      Integrable (fun x => Real.exp (-G p x)) (volume : Measure E) ∧
      0 < ∫ x : E, Real.exp (-G p x) ∧ IsProbabilityMeasure (πbar p) ∧
      (π p).map S = πbar p ∧
      (∀ x, gradient (G p) (S x) = (Real.sqrt c)⁻¹ • gradient (F p) x) ∧
      (∀ t : ℝ, 0 ≤ t →
        (TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing (πbar p) (Real.sqrt t)).map R =
          TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing (π p) (Real.sqrt (t/c))) ∧
      (∀ (νbar : Measure E) (t B : ℝ), IsProbabilityMeasure νbar → 0 ≤ t → 0 ≤ B →
        TechnicalLemmas.Measure.WassersteinSpace.wassersteinDistance νbar
          (TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing (πbar p) (Real.sqrt t)) ^ 2 ≤
            ENNReal.ofReal B →
        TechnicalLemmas.Measure.WassersteinSpace.wassersteinDistance (νbar.map R)
          (TechnicalLemmas.Measure.GaussianSmoothing.gaussianSmoothing (π p) (Real.sqrt (t/c))) ^ 2 ≤
            ENNReal.ofReal (B/c))) := by
  let d : ℝ := Module.finrank ℝ E
  let A := η+τ
  let a := (α:ℝ)+A⁻¹
  let c := (β:ℝ)+A⁻¹
  let k := c/a
  let u := fun p : E × E => p.1+Real.sqrt τ • p.2
  let F := fun p x => U x+A⁻¹/2*‖x-u p‖^2
  let T := fun p x => x-c⁻¹ • gradient (F p) x
  let N := actualIndex T (fun p x => ‖gradient (F p) x‖^2) (a*d)
  let out := fun p => (T p)^[N p] p.1
  let S := fun x : E => Real.sqrt c • x
  let R := fun x : E => (Real.sqrt c)⁻¹ • x
  let G := fun p x => F p (R x)
  have hA : 0 < A := add_pos_of_nonneg_of_pos hη hτ
  have ha : 0 < a := add_pos_of_nonneg_of_pos α.coe_nonneg (inv_pos.mpr hA)
  have hc : 0 < c := add_pos_of_nonneg_of_pos β.coe_nonneg (inv_pos.mpr hA)
  have hs : 0 < Real.sqrt c := Real.sqrt_pos.mpr hc
  have hi : (Real.sqrt c)⁻¹^2=c⁻¹ := by rw [inv_pow,Real.sq_sqrt hc.le]
  have hP := JointReferenceGradientDescent.joint_reference_gradient_descent
    hα hαβ hU hH hη hτ hr hd ν hw
  have hNm : Measurable N := hP.1
  have hom : Measurable out := hP.2.1
  refine ⟨hNm,(by fun_prop : Measurable S).comp hom,fun p => ?_⟩
  have hreg := regularized_hessian hU A⁻¹ (u p)
  have hFH (x v : E) : a*‖v‖^2 ≤ fderiv ℝ (fderiv ℝ (F p)) x v v ∧
      fderiv ℝ (fderiv ℝ (F p)) x v v ≤ c*‖v‖^2 := by
    rw [hreg.2]
    dsimp [a,c]
    constructor <;> nlinarith [(hH x v).1,(hH x v).2]
  obtain ⟨hG,hGH,hI,hZ,hprob,hIG,hZG,hprobG,hmap,hgrad,hsm,hprec⟩ :=
    normalized_laws ha hc hreg.1 hFH
  have hp : ‖gradient (F p) (out p)‖^2 ≤ a*d := (hP.2.2.1 p).1
  have hearly : ∀ j < N p, a*d < ‖gradient (F p) ((T p)^[j] p.1)‖^2 :=
    (hP.2.2.1 p).2.2.2.1
  refine ⟨hp,hearly,?_,hG,hGH,hI,hZ,hprob,hIG,hZG,hprobG,hmap,hgrad,hsm,
    fun νbar t B _ ht _ hbudget => hprec νbar t B ht hbudget⟩
  rw [hgrad,norm_smul,Real.norm_eq_abs,mul_pow,sq_abs,hi]
  have hb := mul_le_mul_of_nonneg_left hp (inv_pos.mpr hc).le
  calc
    c⁻¹*‖gradient (F p) (out p)‖^2 ≤ c⁻¹*(a*d) := hb
    _ = d/k := by dsimp [k]; field_simp

end AutoSamplingTheory.ExampleCases.SmoothedPicardHMC.NormalizedReferenceCall

Exact module and namespace context

Scope and omitted-condition boundaries

  • Fixed-call normalization of the actual first ad-hit reference and actual sampling laws. General beta, coordinate-free finite dimension and eta=0,t=0,r=0,B=0 extend the source; d>0,tau>0,0<alpha<=beta remain required. The outer W2 input and next normalized output precision are distinct supplied guarantees. No sampler achieving the next budget, all-parameter kernel, measurable sampler selection, conditional history or stage costs are proved. The public transport conclusion is the needed inequality, not a full isometry theorem. For source B=k*epsilon^2, B/c=epsilon^2/a; a here denotes regularized curvature. Returned probability is a standard measurable-pushforward consequence, not an extra public conjunct. Both main results remain incomplete.

Source and reuse

ASTIS parents called

Mathlib API called (external library)

  • MeasureTheory.Measure.integral_comp_smul
  • MeasureTheory.tilted_apply_eq_ofReal_integral'
  • MeasureTheory.Measure.map_prod_map
  • MeasureTheory.Measure.map_map
  • ENNReal.mul_iInf_of_ne

Mathematical sources

  • SPHMC Sections6.1 and6.3 normalization convention and next call — Fixed-call normalization of the actual first ad-hit reference and actual sampling laws. General beta, coordinate-free finite dimension and eta=0,t=0,r=0,B=0 extend the source; d>0,tau>0,0<alpha<=beta remain required. The outer W2 input and next normalized output precision are distinct supplied guarantees. No sampler achieving the next budget, all-parameter kernel, measurable sampler selection, conditional history or stage costs are proved. The public transport conclusion is the needed inequality, not a full isometry theorem. For source B=k*epsilon^2, B/c=epsilon^2/a; a here denotes regularized curvature. Returned probability is a standard measurable-pushforward consequence, not an extra public conjunct. Both main results remain incomplete.

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