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import OAI.MathematicalPhysics.Boltzmann.Approximation.PositiveSourceFormula
import OAI.MathematicalPhysics.Boltzmann.Branching.BoundedEntropyProduction
import OAI.MathematicalPhysics.Boltzmann.Branching.LinearCharacteristicBalance
import OAI.MathematicalPhysics.Boltzmann.Compactness.StrongPairMoment
import OAI.MathematicalPhysics.Boltzmann.Compactness.UniformIntegrability
import Mathlib.Analysis.Calculus.Deriv.Inv
namespace OAI
section
/-! # Exact entropy dissipation for positive bounded cutoff densities -/
noncomputable section
open MeasureTheory
open BoltzmannNonuniqueness.VelocityWeight
namespace BoltzmannNonuniqueness.CollisionCompactness
variable {X : Type*} [MeasurableSpace X]
def positiveCutoffProduction (b : ℝ) (f : X × Velocity → ℝ)
(z : (X × (Velocity × Velocity)) × Sphere) : ℝ :=
(1/4:ℝ)*collisionJump (fun p => Real.log (f p/maxwellian p.2)) z*
(truncatedPostRate b f z-truncatedPreRate b f z)
omit [MeasurableSpace X] in
theorem positiveCutoffProduction_nonneg (b : ℝ) (f : X × Velocity → ℝ)
(hf : ∀ p, 0 < f p) (z : (X × (Velocity × Velocity)) × Sphere) :
0 ≤ positiveCutoffProduction b f z := by
have h := mul_nonneg (by norm_num : (0:ℝ) ≤ 1/4) (relative_entropy_production_nonneg b f hf z)
simpa only [positiveCutoffProduction,mul_assoc] using h
theorem cutoff_relative_entropy_identity {μ : Measure X} [SFinite μ] (b : ℝ)
(f : X × Velocity → ℝ)
(hpre : Integrable (fun z => Real.log (f (z.1.1,z.1.2.1)/maxwellian z.1.2.1)*
truncatedPreRate b f z) ((μ.prod (volume : Measure (Velocity × Velocity))).prod sphereArea))
(hpost : Integrable (fun z => Real.log (f (z.1.1,z.1.2.1)/maxwellian z.1.2.1)*
truncatedPostRate b f z) ((μ.prod (volume : Measure (Velocity × Velocity))).prod sphereArea)) :
(∫ p, Real.log (f p/maxwellian p.2)*KineticCollisionNullSets.gain b f p ∂μ.prod volume)-
(∫ p, Real.log (f p/maxwellian p.2)*cutoffLossDensity b f p ∂μ.prod volume) =
-(∫ z, positiveCutoffProduction b f z
∂(μ.prod (volume : Measure (Velocity × Velocity))).prod sphereArea) := by
have hp := (collision_test_marginal (truncatedPostRate b f)
(fun p => Real.log (f p/maxwellian p.2)) hpost).2
have hl := (collision_test_marginal (truncatedPreRate b f)
(fun p => Real.log (f p/maxwellian p.2)) hpre).2
simp only [← cutoffGain_eq_marginal] at hp
simp only [← cutoffLoss_eq_marginal] at hl
rw [hp,hl,cutoff_production_identity b f (fun p => Real.log (f p/maxwellian p.2)) hpre hpost]
simp only [positiveCutoffProduction,mul_assoc,integral_const_mul]
ring
theorem bounded_positive_entropy_identity (hcarleman : Published.GPV2009CarlemanInput)
{μ : Measure X} [IsFiniteMeasure μ] {q A δ b : ℝ}
(hq₁ : 1 < q) (hq₂ : q < 2) (hA : 0 ≤ A) (hδ : 0 < δ) (hb : 0 ≤ b)
{f : X × Velocity → ℝ} (hfm : Measurable f)
(hfl : ∀ p, δ*Real.exp (-2*‖p.2‖^2) ≤ f p) (hfb : ∀ p, f p ≤ A*H q p.2) :
Integrable (positiveCutoffProduction b f)
((μ.prod (volume : Measure (Velocity × Velocity))).prod sphereArea) ∧
(∫ p, Real.log (f p/maxwellian p.2)*collisionSource b f p ∂μ.prod volume) =
-(∫ z, positiveCutoffProduction b f z
∂(μ.prod (volume : Measure (Velocity × Velocity))).prod sphereArea) := by
have hfn : ∀ p, 0 ≤ f p := fun p => (mul_pos hδ (Real.exp_pos _)).le.trans (hfl p)
have hpair := bounded_pair_integrable (μ := μ) hq₂ hA hfm hfn hfb
have hgL := bounded_log_gainLoss_integrable (μ := μ) hcarleman hq₁ hq₂ hA hA hδ hb hfm hfm hfn hfb hfl hfb
have hlog : Measurable (fun p : X × Velocity => Real.log (f p/maxwellian p.2)) := by
have hm : Measurable (fun p : X × Velocity => maxwellian p.2) := by unfold maxwellian; fun_prop
exact (hfm.div hm).log
have hS : MeasurableSet {z : (X × (Velocity × Velocity)) × Sphere | ‖z.1.2.1-z.1.2.2‖ < b} :=
measurableSet_lt (by fun_prop) measurable_const
have hprei := (preRate_integrable hfm hfn hpair).indicator hS
have hposti := (postRate_integrable hfm hfn hpair).indicator hS
have hpren : ∀ z, 0 ≤ truncatedPreRate b f z := fun z =>
Set.indicator_nonneg (fun z _ => preRate_nonneg hfn z) z
have hpostn : ∀ z, 0 ≤ truncatedPostRate b f z := fun z =>
Set.indicator_nonneg (fun z _ => preRate_nonneg hfn (scatterTriple z)) z
have hpre := collision_test_integrable_of_marginal (truncatedPreRate_measurable hfm b)
hpren hprei hlog (by simpa only [← cutoffLoss_eq_marginal] using hgL.2)
have hpost := collision_test_integrable_of_marginal (truncatedPostRate_measurable hfm b)
hpostn hposti hlog (by simpa only [← cutoffGain_eq_marginal] using hgL.1)
obtain ⟨hjpre,hjpost⟩ := collisionJump_integrable b f (fun p => Real.log (f p/maxwellian p.2)) hpre hpost
constructor
· convert (hjpost.sub hjpre).const_mul (1/4:ℝ) using 1
funext z
simp only [positiveCutoffProduction,Pi.sub_apply]
ring
· have hloss := cutoff_loss_ae_eq_frequency hfm hfn hpair b
have hLi : Integrable (fun p => Real.log (f p/maxwellian p.2)*
(f p*KineticCollisionNullSets.frequency b f p)) (μ.prod volume) := by
apply hgL.2.congr
filter_upwards [hloss] with p hp
rw [hp]
calc
_ = (∫ p, Real.log (f p/maxwellian p.2)*KineticCollisionNullSets.gain b f p ∂μ.prod volume)-
(∫ p, Real.log (f p/maxwellian p.2)*cutoffLossDensity b f p ∂μ.prod volume) := by
simp_rw [collisionSource,mul_sub]
rw [integral_sub hgL.1 hLi]
congr 1
apply integral_congr_ae
filter_upwards [hloss] with p hp
rw [hp]
_ = _ := cutoff_relative_entropy_identity b f hpre hpost
end BoltzmannNonuniqueness.CollisionCompactness
end
end
section
/-! # Uniform integrability upgrades positive-difference convergence to strong L1 convergence -/
noncomputable section
open MeasureTheory Filter
open scoped ENNReal Topology
namespace BoltzmannNonuniqueness.Compactness
open TransportPrimitive
variable {X : Type*} [MeasurableSpace X] {μ : Measure X}
theorem positiveDifference_L1 {u v : ℕ → X → ℝ}
(hum : ∀ n, Measurable (u n)) (hvm : ∀ n, Measurable (v n))
(hu : ∀ n x, 0 ≤ u n x) (hv : ∀ n x, 0 ≤ v n x)
(hui : UniformIntegrable u 1 μ) (hvi : UniformIntegrable v 1 μ)
(hd : Tendsto (fun n => eLpNorm (fun x => positiveDifference (u n x) (v n x)) 1 μ)
atTop (𝓝 0)) :
Tendsto (fun n => eLpNorm (fun x => u n x-v n x) 1 μ) atTop (𝓝 0) := by
have hclip (K : ℝ) (hK : 0 ≤ K) :
Tendsto (fun n => eLpNorm (fun x => min (u n x) K-min (v n x) K) 1 μ) atTop (𝓝 0) := by
have hmul := ENNReal.Tendsto.const_mul (a := ENNReal.ofReal (1+2*K)) hd
(Or.inr ENNReal.ofReal_ne_top)
simp only [mul_zero] at hmul
apply tendsto_of_tendsto_of_tendsto_of_le_of_le tendsto_const_nhds hmul (fun _ => zero_le)
intro n
apply eLpNorm_le_mul_eLpNorm_of_ae_le_mul
(((hum n).min measurable_const).sub ((hvm n).min measurable_const)).aestronglyMeasurable
exact ae_of_all _ (fun x => by
simpa only [Real.norm_eq_abs,Pi.sub_apply] using
min_difference_le_positiveDifference (hu n x) (hv n x) hK)
apply ENNReal.tendsto_nhds_zero.mpr
intro ε hε
have hε4 : 0 < ε/4 := ENNReal.div_pos hε.ne' (by norm_num)
obtain ⟨C,hC⟩ := uniform_min_truncation hum hu hui hε4
obtain ⟨D,hD⟩ := uniform_min_truncation hvm hv hvi hε4
let K : ℝ := max (C:ℝ) (D:ℝ)
have hK : 0 ≤ K := C.coe_nonneg.trans (le_max_left _ _)
filter_upwards [ENNReal.tendsto_nhds_zero.mp (hclip K hK) (ε/4) hε4] with n hn
have he : (fun x => u n x-v n x) =
(fun x => u n x-min (u n x) K)+
(fun x => min (u n x) K-min (v n x) K)+
(fun x => min (v n x) K-v n x) := by
funext x
simp only [Pi.add_apply]
ring
rw [he]
calc
_ ≤ (eLpNorm (fun x => u n x-min (u n x) K) 1 μ+
eLpNorm (fun x => min (u n x) K-min (v n x) K) 1 μ)+
eLpNorm (fun x => min (v n x) K-v n x) 1 μ :=
(eLpNorm_add_le (by norm_num)).trans
(add_le_add (eLpNorm_add_le (by norm_num)) le_rfl)
_ ≤ (ε/4+ε/4)+ε/4 := by
apply add_le_add (add_le_add (hC K (le_max_left _ _) n) hn)
change eLpNorm ((fun x => min (v n x) K)-v n) 1 μ ≤ _
rw [eLpNorm_sub_comm]
exact hD K (le_max_right _ _) n
_ ≤ ε := by
calc
(ε/4+ε/4)+ε/4 ≤ (ε/4+ε/4)+(ε/4+ε/4) := add_le_add le_rfl le_self_add
_ = 4*(ε/4) := by ring
_ = ε := ENNReal.mul_div_cancel (by norm_num) (by norm_num)
end BoltzmannNonuniqueness.Compactness
end
end
section
/-! # Absolute continuity and evolution of the bounded positive-path difference -/
noncomputable section
open MeasureTheory Set
namespace BoltzmannNonuniqueness.TransportPrimitive
theorem inv_lipschitzOn_one : LipschitzOnWith 1 (fun x : ℝ => x⁻¹) (Ici 1) := by
rw [lipschitzOnWith_iff_dist_le_mul]
intro x hx y hy
have hx0 : 0 < x := lt_of_lt_of_le zero_lt_one hx
have hy0 : 0 < y := lt_of_lt_of_le zero_lt_one hy
have he : x⁻¹-y⁻¹ = (y-x)/(x*y) := by field_simp
simp only [Real.dist_eq,NNReal.coe_one,one_mul]
rw [he,abs_div,abs_of_pos (mul_pos hx0 hy0),abs_sub_comm y x]
apply (div_le_iff₀ (mul_pos hx0 hy0)).mpr
have hxy : 1 ≤ x*y := by simpa only [one_mul] using mul_le_mul hx hy (by norm_num) hx0.le
nlinarith [abs_nonneg (x-y)]
theorem positiveDifference_absolutelyContinuous {T : ℝ} (hT : 0 ≤ T) {u v : ℝ → ℝ}
(hu : AbsolutelyContinuousOnInterval u 0 T) (hv : AbsolutelyContinuousOnInterval v 0 T)
(hu0 : ∀ t ∈ Icc 0 T, 0 ≤ u t) (hv0 : ∀ t ∈ Icc 0 T, 0 ≤ v t) :
AbsolutelyContinuousOnInterval (fun t => positiveDifference (u t) (v t)) 0 T := by
have hc : AbsolutelyContinuousOnInterval (fun _ : ℝ => (1:ℝ)) 0 T :=
(LipschitzWith.const 1).lipschitzOnWith.absolutelyContinuousOnInterval
have hd : AbsolutelyContinuousOnInterval (fun t => 1+u t+v t) 0 T := (hc.add hu).add hv
have hi := inv_lipschitzOn_one.comp_absolutelyContinuousOnInterval
(fun t ht => by
have hmem : t ∈ Icc 0 T := by simpa only [uIcc_of_le hT] using ht
change 1 ≤ 1+u t+v t
linarith [hu0 t hmem,hv0 t hmem]) hd
exact (hu.sub hv).mul hi
theorem positiveDifference_hasDerivAt {u v : ℝ → ℝ} {du dv t : ℝ}
(hu : HasDerivAt u du t) (hv : HasDerivAt v dv t) (hu0 : 0 ≤ u t) (hv0 : 0 ≤ v t) :
HasDerivAt (fun s => positiveDifference (u s) (v s))
(((du-dv)*(1+u t+v t)-(u t-v t)*(du+dv))/(1+u t+v t)^2) t := by
exact (hu.sub hv).div ((hu.const_add 1).add hv) (by positivity)
theorem positiveDifference_evolution {u v : ℝ → ℝ} {a b k l e f t : ℝ}
(hu : HasDerivAt u (a-k*u t+e) t) (hv : HasDerivAt v (b-l*v t+f) t)
(hu0 : 0 ≤ u t) (hv0 : 0 ≤ v t) :
HasDerivAt (fun s => positiveDifference (u s) (v s))
(positiveDifferenceForcing (u t) (v t) a b k l e f-
positiveDifferenceDamping (u t) (v t) a b k l e f*positiveDifference (u t) (v t)) t := by
have h := positiveDifference_hasDerivAt hu hv hu0 hv0
rwa [positiveDifference_derivative_identity hu0 hv0] at h
end BoltzmannNonuniqueness.TransportPrimitive
end
end
section
/-! # Stability in a bounded metric for positive characteristic profiles -/
noncomputable section
open MeasureTheory Set
namespace BoltzmannNonuniqueness.TransportPrimitive
theorem positiveDifference_stability {T : ℝ} (hT : 0 ≤ T)
{u v a b k l e f : ℝ → ℝ}
(hu : AbsolutelyContinuousOnInterval u 0 T) (hv : AbsolutelyContinuousOnInterval v 0 T)
(hu0 : ∀ t ∈ Icc 0 T, 0 ≤ u t) (hv0 : ∀ t ∈ Icc 0 T, 0 ≤ v t)
(ha : ∀ t ∈ Icc 0 T, 0 ≤ a t) (hb : ∀ t ∈ Icc 0 T, 0 ≤ b t)
(hk0 : ∀ t ∈ Icc 0 T, 0 ≤ k t) (hl0 : ∀ t ∈ Icc 0 T, 0 ≤ l t)
(he0 : ∀ t ∈ Icc 0 T, 0 ≤ e t) (hf0 : ∀ t ∈ Icc 0 T, 0 ≤ f t)
(hdi : IntervalIntegrable
(fun t => positiveDifferenceDamping (u t) (v t) (a t) (b t) (k t) (l t) (e t) (f t)) volume 0 T)
(hri : IntervalIntegrable
(fun t => positiveDifferenceForcing (u t) (v t) (a t) (b t) (k t) (l t) (e t) (f t)) volume 0 T)
(hdu : ∀ᵐ t, t ∈ Icc 0 T → HasDerivAt u (a t-k t*u t+e t) t)
(hdv : ∀ᵐ t, t ∈ Icc 0 T → HasDerivAt v (b t-l t*v t+f t) t) :
|positiveDifference (u T) (v T)| ≤ |positiveDifference (u 0) (v 0)|+
∫ t in 0..T, |positiveDifferenceForcing (u t) (v t) (a t) (b t) (k t) (l t) (e t) (f t)| := by
have hw := positiveDifference_absolutelyContinuous hT hu hv hu0 hv0
apply damped_path_abs_le hT hw hdi hri
· intro t ht
exact positiveDifference_damping_nonneg (hu0 t ht) (hv0 t ht) (ha t ht) (hb t ht)
(hk0 t ht) (hl0 t ht) (he0 t ht) (hf0 t ht)
· filter_upwards [hdu,hdv] with t htu htv ht
exact positiveDifference_evolution (htu ht) (htv ht) (hu0 t ht) (hv0 t ht)
end BoltzmannNonuniqueness.TransportPrimitive
end
end
section
/-! # Integrability of the exact bounded positive-comparison equation -/
noncomputable section
open MeasureTheory Set
namespace BoltzmannNonuniqueness.TransportPrimitive
theorem positiveComparison_integrable {T : ℝ} (hT : 0 ≤ T)
{u v a b k l e f : ℝ → ℝ}
(hu : ContinuousOn u (Icc 0 T)) (hv : ContinuousOn v (Icc 0 T))
(hu0 : ∀ t ∈ Icc 0 T, 0 ≤ u t) (hv0 : ∀ t ∈ Icc 0 T, 0 ≤ v t)
(ha : IntervalIntegrable a volume 0 T) (hb : IntervalIntegrable b volume 0 T)
(hk : IntervalIntegrable k volume 0 T) (hl : IntervalIntegrable l volume 0 T)
(he : IntervalIntegrable e volume 0 T) (hf : IntervalIntegrable f volume 0 T) :
IntervalIntegrable (fun t =>
positiveDifferenceDamping (u t) (v t) (a t) (b t) (k t) (l t) (e t) (f t)) volume 0 T ∧
IntervalIntegrable (fun t =>
positiveDifferenceForcing (u t) (v t) (a t) (b t) (k t) (l t) (e t) (f t)) volume 0 T := by
have hd0 t (ht : t ∈ Icc 0 T) : 1+u t+v t ≠ 0 := by
have := hu0 t ht
have := hv0 t ht
positivity
have hc : ContinuousOn (fun t => (1+u t+v t)⁻¹) (uIcc 0 T) := by
rw [uIcc_of_le hT]
exact ((continuousOn_const.add hu).add hv).inv₀ hd0
have hq : ContinuousOn (fun t => (u t+v t+4*u t*v t)/(2*(1+u t+v t)^2))
(uIcc 0 T) := by
rw [uIcc_of_le hT]
apply ((hu.add hv).add ((continuousOn_const.mul hu).mul hv)).div
(continuousOn_const.mul (((continuousOn_const.add hu).add hv).pow 2))
intro t ht
exact mul_ne_zero (by norm_num) (pow_ne_zero _ (hd0 t ht))
constructor
· have h := (((ha.add hb).add he).add hf |>.add ((hk.add hl).div_const 2)).mul_continuousOn hc
convert h using 1
funext t
exact div_eq_mul_inv _ _
· have h := (((ha.sub hb).add he).sub hf).mul_continuousOn hc
have h' := (hl.sub hk).mul_continuousOn hq
convert h.add h' using 1
funext t
unfold positiveDifferenceForcing
ring
theorem positiveComparison_error_integrable {T : ℝ} (hT : 0 ≤ T)
{u v a b k l e f : ℝ → ℝ}
(hu : ContinuousOn u (Icc 0 T)) (hv : ContinuousOn v (Icc 0 T))
(hu0 : ∀ t ∈ Icc 0 T, 0 ≤ u t) (hv0 : ∀ t ∈ Icc 0 T, 0 ≤ v t)
(ha : IntervalIntegrable a volume 0 T) (hb : IntervalIntegrable b volume 0 T)
(hk : IntervalIntegrable k volume 0 T) (hl : IntervalIntegrable l volume 0 T)
(he : IntervalIntegrable e volume 0 T) (hf : IntervalIntegrable f volume 0 T) :
IntervalIntegrable (fun t => |a t-b t|/(1+u t+v t)+e t/(1+u t)+f t/(1+v t)+|k t-l t|)
volume 0 T := by
have hdu t (ht : t ∈ Icc 0 T) : 1+u t ≠ 0 := by have := hu0 t ht; positivity
have hdv t (ht : t ∈ Icc 0 T) : 1+v t ≠ 0 := by have := hv0 t ht; positivity
have hd t (ht : t ∈ Icc 0 T) : 1+u t+v t ≠ 0 := by
have := hu0 t ht
have := hv0 t ht
positivity
have cu : ContinuousOn (fun t => (1+u t)⁻¹) (uIcc 0 T) := by
rw [uIcc_of_le hT]; exact (continuousOn_const.add hu).inv₀ hdu
have cv : ContinuousOn (fun t => (1+v t)⁻¹) (uIcc 0 T) := by
rw [uIcc_of_le hT]; exact (continuousOn_const.add hv).inv₀ hdv
have cd : ContinuousOn (fun t => (1+u t+v t)⁻¹) (uIcc 0 T) := by
rw [uIcc_of_le hT]; exact ((continuousOn_const.add hu).add hv).inv₀ hd
have h := ((((ha.sub hb).abs.mul_continuousOn cd).add
(he.mul_continuousOn cu)).add (hf.mul_continuousOn cv)).add (hk.sub hl).abs
simpa only [div_eq_mul_inv] using h
end BoltzmannNonuniqueness.TransportPrimitive
end
end
section
/-! # A positive-path stability bound using only the physical source discrepancies -/
noncomputable section
open MeasureTheory Set
namespace BoltzmannNonuniqueness.TransportPrimitive
theorem positiveDifference_error_bound {T : ℝ} (hT : 0 ≤ T)
{u v a b k l e f : ℝ → ℝ}
(hu : AbsolutelyContinuousOnInterval u 0 T) (hv : AbsolutelyContinuousOnInterval v 0 T)
(hu0 : ∀ t ∈ Icc 0 T, 0 ≤ u t) (hv0 : ∀ t ∈ Icc 0 T, 0 ≤ v t)
(ha0 : ∀ t ∈ Icc 0 T, 0 ≤ a t) (hb0 : ∀ t ∈ Icc 0 T, 0 ≤ b t)
(hk0 : ∀ t ∈ Icc 0 T, 0 ≤ k t) (hl0 : ∀ t ∈ Icc 0 T, 0 ≤ l t)
(he0 : ∀ t ∈ Icc 0 T, 0 ≤ e t) (hf0 : ∀ t ∈ Icc 0 T, 0 ≤ f t)
(ha : IntervalIntegrable a volume 0 T) (hb : IntervalIntegrable b volume 0 T)
(hk : IntervalIntegrable k volume 0 T) (hl : IntervalIntegrable l volume 0 T)
(he : IntervalIntegrable e volume 0 T) (hf : IntervalIntegrable f volume 0 T)
(hdu : ∀ᵐ t, t ∈ Icc 0 T → HasDerivAt u (a t-k t*u t+e t) t)
(hdv : ∀ᵐ t, t ∈ Icc 0 T → HasDerivAt v (b t-l t*v t+f t) t) :
|positiveDifference (u T) (v T)| ≤ |positiveDifference (u 0) (v 0)|+
∫ t in 0..T, |a t-b t|/(1+u t+v t)+e t/(1+u t)+f t/(1+v t)+|k t-l t| := by
have huc : ContinuousOn u (Icc 0 T) := by
simpa only [uIcc_of_le hT] using hu.continuousOn
have hvc : ContinuousOn v (Icc 0 T) := by
simpa only [uIcc_of_le hT] using hv.continuousOn
obtain ⟨hdi,hri⟩ := positiveComparison_integrable hT huc hvc hu0 hv0 ha hb hk hl he hf
have h := positiveDifference_stability hT hu hv hu0 hv0 ha0 hb0 hk0 hl0 he0 hf0 hdi hri hdu hdv
apply h.trans
apply add_le_add le_rfl
apply intervalIntegral.integral_mono_on hT hri.abs
(positiveComparison_error_integrable hT huc hvc hu0 hv0 ha hb hk hl he hf)
intro t ht
exact positiveDifference_forcing_bound (hu0 t ht) (hv0 t ht) (he0 t ht) (hf0 t ht)
end BoltzmannNonuniqueness.TransportPrimitive
end
end
end OAI