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import Mathlib
import OAI.Probability.JammingConcavity.GaussianStepSlope
namespace OAI
/-! Gaussian Step Right. -/
noncomputable section
open MeasureTheory ProbabilityTheory Set
open scoped NNReal ENNReal
open Set Filter
open scoped Topology
open MeasureTheory ProbabilityTheory Filter Set
open scoped ENNReal NNReal Topology BigOperators
open MeasureTheory Filter Set
open scoped ENNReal NNReal BigOperators
open MeasureTheory ProbabilityTheory Set Filter
open scoped ENNReal NNReal Topology
open scoped NNReal ENNReal Topology
open scoped NNReal Topology
open MeasureTheory ProbabilityTheory Set Filter
open scoped Topology
namespace MicroscopicJamming
def gaussianStepRightCoefficient : List (ℝ × ℝ) → ℝ → ℝ
| [], _ => 0
| (a,T)::rs,t => if t < T then a else gaussianStepRightCoefficient rs (t-T)
lemma gaussianStepRightCoefficient_bounds {rs : List (ℝ × ℝ)}
(hrs : ∀ r ∈ rs, 0 ≤ r.1 ∧ r.1 ≤ 1 ∧ 0 ≤ r.2) (t : ℝ) :
0 ≤ gaussianStepRightCoefficient rs t ∧ gaussianStepRightCoefficient rs t ≤ 1 := by
induction rs generalizing t with
| nil => simp [gaussianStepRightCoefficient]
| cons r rs ih =>
have hr := hrs r (by simp)
have htail : ∀ v ∈ rs, 0 ≤ v.1 ∧ v.1 ≤ 1 ∧ 0 ≤ v.2 := fun v hv => hrs v (by simp [hv])
by_cases h : t < r.2
· simpa [gaussianStepRightCoefficient,h] using And.intro hr.1 hr.2.1
· simpa [gaussianStepRightCoefficient,h] using ih htail (t-r.2)
lemma gaussianStepRightCoefficient_trace (rs : List (ℝ × ℝ)) (t : ℝ) :
∃ ε : ℝ, 0 < ε ∧ ∀ s ∈ Ioo t (t+ε),
gaussianStepCoefficient rs s=gaussianStepRightCoefficient rs t := by
induction rs generalizing t with
| nil => exact ⟨1,by norm_num,fun _ _ => rfl⟩
| cons r rs ih =>
by_cases h : t < r.2
· refine ⟨r.2-t,sub_pos.mpr h,?_⟩
intro s hs
have hsT : s ≤ r.2 := by linarith [hs.2]
simp [gaussianStepCoefficient,gaussianStepRightCoefficient,h,hsT]
· obtain ⟨ε,hε,he⟩ := ih (t-r.2)
refine ⟨ε,hε,?_⟩
intro s hs
have hsT : ¬s ≤ r.2 := by linarith [hs.1,le_of_not_gt h]
have hs' : s-r.2 ∈ Ioo (t-r.2) (t-r.2+ε) := by
constructor <;> linarith [hs.1,hs.2]
simpa [gaussianStepCoefficient,gaussianStepRightCoefficient,h,hsT] using he (s-r.2) hs'
lemma gaussianStepRightCoefficient_close {rs ss : List (ℝ × ℝ)} {Q δ : ℝ}
(hδ : ∀ t ∈ Icc 0 Q, |gaussianStepCoefficient rs t-gaussianStepCoefficient ss t| ≤ δ)
{t : ℝ} (ht : t ∈ Ico 0 Q) :
|gaussianStepRightCoefficient rs t-gaussianStepRightCoefficient ss t| ≤ δ := by
obtain ⟨r,hr,hrtrace⟩ := gaussianStepRightCoefficient_trace rs t
obtain ⟨s,hs,hstrace⟩ := gaussianStepRightCoefficient_trace ss t
let ε := min r (min s (Q-t))
have hε : 0 < ε := lt_min hr (lt_min hs (sub_pos.mpr ht.2))
have hεr : ε ≤ r := min_le_left _ _
have hεs : ε ≤ s := (min_le_right _ _).trans (min_le_left _ _)
have hεQ : ε ≤ Q-t := (min_le_right _ _).trans (min_le_right _ _)
have hr' : t+ε/2 ∈ Ioo t (t+r) := by constructor <;> linarith
have hs' : t+ε/2 ∈ Ioo t (t+s) := by constructor <;> linarith
have ht' : t+ε/2 ∈ Icc 0 Q := by constructor <;> linarith [ht.1]
have hh := hδ (t+ε/2) ht'
rwa [hrtrace _ hr',hstrace _ hs'] at hh
lemma gaussianStepPath_cons_ge (r : ℝ × ℝ) (rs : List (ℝ × ℝ))
(hrs : ∀ v ∈ rs, 0 ≤ v.2) (u : ℝ → ℝ) {t : ℝ} (ht : r.2 ≤ t) :
gaussianStepPath (r::rs) u t=gaussianStepPath rs u (t-r.2) := by
rcases ht.lt_or_eq with h | h
· exact gaussianStepPath_cons_gt r rs u h
· rw [← h,gaussianStepPath_cons_le r rs u le_rfl,sub_self,gaussianStepPath_zero hrs u]
funext x
exact gaussianRowOperator_zero _ _ _
lemma gaussianStepPath_right_pde {u : ℝ → ℝ} {A B C κ Q : ℝ}
(hQ : 0 < Q) (hu : RowAnalyticTerminal u A B C κ Q)
{rs : List (ℝ × ℝ)} (hrs : ∀ r ∈ rs, 0 ≤ r.1 ∧ r.1 ≤ 1 ∧ 0 ≤ r.2)
(hsum : gaussianStepTime rs ≤ Q) {t : ℝ} (ht : t ∈ Ico 0 (gaussianStepTime rs)) (x : ℝ) :
HasDerivWithinAt (fun s => gaussianStepPath rs u s x)
(-(1/2:ℝ)*(deriv (deriv (gaussianStepPath rs u t)) x+
gaussianStepRightCoefficient rs t*(deriv (gaussianStepPath rs u t) x)^2)) (Ici t) t := by
induction rs generalizing t with
| nil => simp [gaussianStepTime] at ht
| cons r rs ih =>
have hr := hrs r (by simp)
have htail : ∀ v ∈ rs, 0 ≤ v.1 ∧ v.1 ≤ 1 ∧ 0 ≤ v.2 := fun v hv => hrs v (by simp [hv])
have htailT : ∀ v ∈ rs, 0 ≤ v.2 := fun v hv => (htail v hv).2.2
have htot : gaussianStepTime (r::rs)=r.2+gaussianStepTime rs := by simp [gaussianStepTime]
have hR : gaussianStepTime rs ≤ Q := by rw [htot] at hsum; linarith
by_cases h : t < r.2
· have htw := gaussian_composition_twice hQ hu htail hR
have hd0 := (Twice.gaussianRowOperator_calculus htw hr.1 (sub_pos.mpr h)).2.2 x
have hd := hd0.comp_const_sub r.2 t
have he : (fun s => gaussianStepPath (r::rs) u s x) =ᶠ[𝓝 t]
(fun s => gaussianRowOperator r.1 (r.2-s) (gaussianRowComposition rs u) x) := by
filter_upwards [eventually_lt_nhds h] with s hs
exact congrFun (gaussianStepPath_cons_le r rs u hs.le) x
have hh := hd.congr_of_eventuallyEq he
rw [gaussianStepPath_cons_le r rs u h.le]
simpa only [gaussianStepRightCoefficient,ite_eq_left h,neg_mul] using hh.hasDerivWithinAt (s := Ici t)
· have hge : r.2 ≤ t := le_of_not_gt h
have ht' : t-r.2 ∈ Ico 0 (gaussianStepTime rs) := by
rw [htot] at ht
constructor <;> linarith [ht.2]
have hi := ih htail hR ht'
have hdsub : HasDerivWithinAt (fun s : ℝ => s-r.2) 1 (Ici t) t :=
((hasDerivAt_id t).sub_const r.2).hasDerivWithinAt
have hmap : MapsTo (fun s : ℝ => s-r.2) (Ici t) (Ici (t-r.2)) := by
intro s hs
exact sub_le_sub_right hs r.2
have hd := hi.scomp t hdsub hmap
have he : (fun s => gaussianStepPath (r::rs) u s x) =ᶠ[𝓝[Ici t] t]
(fun s => gaussianStepPath rs u (s-r.2) x) := by
filter_upwards [self_mem_nhdsWithin] with s hs
exact congrFun (gaussianStepPath_cons_ge r rs htailT u (hge.trans hs)) x
have hh := hd.congr_of_eventuallyEq_of_mem he (show t ∈ Ici t from by simp)
rw [gaussianStepPath_cons_ge r rs htailT u hge]
simpa only [Function.comp_def,one_smul,gaussianStepRightCoefficient,ite_eq_right h] using hh
end MicroscopicJamming
open Set Filter
open scoped Topology
namespace MicroscopicJamming
lemma localMax_second_deriv_nonpos {f : ℝ → ℝ} {x : ℝ}
(hf : Differentiable ℝ f) (hm : IsLocalMax f x) : deriv (deriv f) x ≤ 0 := by
by_contra hn
have hp : 0 < deriv (deriv f) x := lt_of_not_ge hn
have hzero : deriv f x=0 := hm.deriv_eq_zero
have hsign := eventually_nhdsWithin_sign_eq_of_deriv_pos hp hzero
have hright : ∀ᶠ y in 𝓝[>] x, 0 < deriv f y :=
deriv_pos_right_of_sign_deriv (hsign.filter_mono nhdsWithin_le_nhds)
obtain ⟨r,hr,hh⟩ := Metric.mem_nhdsWithin_iff.mp hright
obtain ⟨s,hs,hmax⟩ := Metric.eventually_nhds_iff.mp hm
let y := x+min r s/2
have hry : x<y := by dsimp [y]; linarith [lt_min hr hs]
have hdy : dist y x < r := by
rw [Real.dist_eq,abs_of_pos (sub_pos.mpr hry)]
dsimp [y]; linarith [min_le_left r s]
have hsy : dist y x < s := by
rw [Real.dist_eq,abs_of_pos (sub_pos.mpr hry)]
dsimp [y]; linarith [min_le_right r s]
have hmono : StrictMonoOn f (Icc x y) := by
apply strictMonoOn_of_deriv_pos (convex_Icc _ _) hf.continuous.continuousOn
intro z hz
rw [interior_Icc] at hz
apply hh ⟨?_,hz.1⟩
rw [Metric.mem_ball,Real.dist_eq,abs_of_pos (sub_pos.mpr hz.1)]
have hd : y-x<r := by simpa [Real.dist_eq,abs_of_pos (sub_pos.mpr hry)] using hdy
linarith [hz.2]
exact (not_lt_of_ge (hmax hsy)) (hmono ⟨le_rfl,hry.le⟩ ⟨hry.le,le_rfl⟩ hry)
lemma backward_strict_compact {Q R : ℝ} (hQ : 0 < Q) (hR : 0 < R)
{U b d : ℝ → ℝ → ℝ}
(hc : ContinuousOn (fun p : ℝ × ℝ => U p.1 p.2) (Icc 0 Q ×ˢ Icc (-R) R))
(hx : ∀ t ∈ Icc 0 Q, Differentiable ℝ (U t))
(ht : ∀ t ∈ Ico 0 Q, ∀ x, HasDerivWithinAt (fun s => U s x) (d t x) (Ici t) t)
(hp : ∀ t ∈ Ico 0 Q, ∀ x ∈ Ioo (-R) R,
0 < d t x+(1/2:ℝ)*deriv (deriv (U t)) x+b t x*deriv (U t) x)
(hterm : ∀ x ∈ Icc (-R) R, U Q x ≤ 0)
(hleft : ∀ t ∈ Icc 0 Q, U t (-R) ≤ 0)
(hright : ∀ t ∈ Icc 0 Q, U t R ≤ 0) :
∀ t ∈ Icc 0 Q, ∀ x ∈ Icc (-R) R, U t x ≤ 0 := by
have hne : (Icc 0 Q ×ˢ Icc (-R) R).Nonempty :=
⟨(0,0),⟨le_rfl,hQ.le⟩,by constructor <;> linarith⟩
obtain ⟨p,hpS,hmax⟩ := (isCompact_Icc.prod isCompact_Icc).exists_isMaxOn hne hc
suffices h : U p.1 p.2 ≤ 0 by
intro t ht' x hx'
exact (hmax (show (t,x) ∈ Icc 0 Q ×ˢ Icc (-R) R from ⟨ht',hx'⟩)).trans h
by_contra hn
have hpos : 0 < U p.1 p.2 := lt_of_not_ge hn
have htQ : p.1 < Q := lt_of_le_of_ne hpS.1.2 (by
intro he
have hh := hterm p.2 hpS.2
rw [← he] at hh
exact (not_le_of_gt hpos) hh)
have hxl : -R < p.2 := lt_of_le_of_ne hpS.2.1 (by
intro he
have hh := hleft p.1 hpS.1
rw [he] at hh
exact (not_le_of_gt hpos) hh)
have hxr : p.2 < R := lt_of_le_of_ne hpS.2.2 (by
intro he
have hh := hright p.1 hpS.1
rw [← he] at hh
exact (not_le_of_gt hpos) hh)
have hxmax : IsMaxOn (U p.1) (Icc (-R) R) p.2 :=
fun x hx' => hmax (show (p.1,x) ∈ Icc 0 Q ×ˢ Icc (-R) R from ⟨hpS.1,hx'⟩)
have hxlocal : IsLocalMax (U p.1) p.2 :=
hxmax.isLocalMax (Icc_mem_nhds hxl hxr)
have hzero := hxlocal.deriv_eq_zero
have hsecond := localMax_second_deriv_nonpos (hx p.1 hpS.1) hxlocal
have htmax : IsMaxOn (fun t => U t p.2) (Icc p.1 Q) p.1 :=
fun t ht' => hmax (show (t,p.2) ∈ Icc 0 Q ×ˢ Icc (-R) R from ⟨⟨hpS.1.1.trans ht'.1,ht'.2⟩,hpS.2⟩)
have htan : Q-p.1 ∈ posTangentConeAt (Icc p.1 Q) p.1 :=
sub_mem_posTangentConeAt_of_segment_subset (segment_eq_Icc htQ.le ▸ Subset.rfl)
have hd := (ht p.1 ⟨hpS.1.1,htQ⟩ p.2).mono (show Icc p.1 Q ⊆ Ici p.1 from fun _ h => h.1)
have hnonpos : (Q-p.1)*d p.1 p.2 ≤ 0 := by
simpa only [ContinuousLinearMap.smulRight_apply,ContinuousLinearMap.toSpanSingleton_apply,one_apply_eq_self,smul_eq_mul] using
htmax.isLocalMaxOn.hasFDerivWithinAt_nonpos hd htan
have hdt : d p.1 p.2 ≤ 0 := by nlinarith [sub_pos.mpr htQ]
have hstrict := hp p.1 ⟨hpS.1.1,htQ⟩ p.2 ⟨hxl,hxr⟩
rw [hzero,mul_zero,add_zero] at hstrict
linarith
def quarticBarrier (ε c Q t x : ℝ) : ℝ :=
ε*Real.exp (c*(Q-t))*(1+x^2)^2
lemma quarticBarrier_space (ε c Q t x : ℝ) :
HasDerivAt (quarticBarrier ε c Q t)
(ε*Real.exp (c*(Q-t))*(4*x*(1+x^2))) x := by
unfold quarticBarrier
convert (((hasDerivAt_const x 1).add ((hasDerivAt_id x).pow 2)).pow 2).const_mul
(ε*Real.exp (c*(Q-t))) using 1 <;> first | rfl | (simp only [Pi.add_apply,Pi.pow_apply,id_eq]; ring)
lemma quarticBarrier_space2 (ε c Q t x : ℝ) :
HasDerivAt (deriv (quarticBarrier ε c Q t))
(ε*Real.exp (c*(Q-t))*(4+12*x^2)) x := by
have he : deriv (quarticBarrier ε c Q t)=
fun y => ε*Real.exp (c*(Q-t))*(4*y*(1+y^2)) :=
funext fun y => (quarticBarrier_space ε c Q t y).deriv
rw [he]
convert (((hasDerivAt_id x).const_mul 4).mul
((hasDerivAt_const x 1).add ((hasDerivAt_id x).pow 2))).const_mul
(ε*Real.exp (c*(Q-t))) using 1 <;> first | rfl | (simp only [Pi.add_apply,Pi.pow_apply,id_eq]; ring)
lemma quarticBarrier_time (ε c Q t x : ℝ) :
HasDerivAt (fun s => quarticBarrier ε c Q s x)
(-c*quarticBarrier ε c Q t x) t := by
unfold quarticBarrier
convert ((((hasDerivAt_const t Q).sub (hasDerivAt_id t)).const_mul c).exp.const_mul ε).mul_const
((1+x^2)^2) using 1 <;> first | rfl | (simp only [Pi.sub_apply,id_eq]; ring)
lemma quartic_transport_neg {K b x : ℝ} (hK : 0 ≤ K)
(hb : |b| ≤ K*(1+|x|)) :
-(8*K+8)*(1+x^2)^2+(1/2:ℝ)*(4+12*x^2)+b*(4*x*(1+x^2)) < 0 := by
have hnorm : (1+|x|)*|x| ≤ 2*(1+x^2) := by
nlinarith [sq_abs x,sq_nonneg (|x|-1)]
have hbx : b*x ≤ 2*K*(1+x^2) := calc
b*x ≤ |b*x| := le_abs_self _
_ = |b| * |x| := abs_mul _ _
_ ≤ K*(1+|x|)*|x| := mul_le_mul_of_nonneg_right hb (abs_nonneg _)
_ ≤ 2*K*(1+x^2) := by nlinarith [mul_le_mul_of_nonneg_left hnorm hK]
have ht := mul_le_mul_of_nonneg_left hbx (show 0 ≤ 4*(1+x^2) by positivity)
nlinarith [sq_nonneg x,sq_nonneg (x^2)]
lemma backward_quartic_bound {Q K C : ℝ} (hQ : 0 < Q) (hK : 0 ≤ K) (hC : 0 ≤ C)
{U b d : ℝ → ℝ → ℝ}
(hc : ContinuousOn (fun p : ℝ × ℝ => U p.1 p.2) (Icc 0 Q ×ˢ univ))
(hx : ∀ t ∈ Icc 0 Q, Differentiable ℝ (U t) ∧ Differentiable ℝ (deriv (U t)))
(ht : ∀ t ∈ Ico 0 Q, ∀ x, HasDerivWithinAt (fun s => U s x) (d t x) (Ici t) t)
(hb : ∀ t ∈ Icc 0 Q, ∀ x, |b t x| ≤ K*(1+|x|))
(hg : ∀ t ∈ Icc 0 Q, ∀ x, U t x ≤ C*(1+x^2))
(hp : ∀ t ∈ Ico 0 Q, ∀ x,
0 ≤ d t x+(1/2:ℝ)*deriv (deriv (U t)) x+b t x*deriv (U t) x)
(hterm : ∀ x, U Q x ≤ 0)
{ε : ℝ} (hε : 0 < ε) :
∀ t ∈ Icc 0 Q, ∀ x, U t x ≤ quarticBarrier ε (8*K+8) Q t x := by
let c := 8*K+8
have hcpos : 0 ≤ c := by dsimp [c]; positivity
let V : ℝ → ℝ → ℝ := fun t x => U t x-quarticBarrier ε c Q t x
let vd : ℝ → ℝ → ℝ := fun t x => d t x+c*quarticBarrier ε c Q t x
have hvx (t : ℝ) (ht' : t ∈ Icc 0 Q) (x : ℝ) :
HasDerivAt (V t) (deriv (U t) x-ε*Real.exp (c*(Q-t))*(4*x*(1+x^2))) x :=
((hx t ht').1 x).hasDerivAt.sub (quarticBarrier_space ε c Q t x)
have hvxx (t : ℝ) (ht' : t ∈ Icc 0 Q) (x : ℝ) :
deriv (deriv (V t)) x=deriv (deriv (U t)) x-ε*Real.exp (c*(Q-t))*(4+12*x^2) := by
have he : deriv (V t)=fun y => deriv (U t) y-deriv (quarticBarrier ε c Q t) y := by
ext y
rw [(hvx t ht' y).deriv,(quarticBarrier_space ε c Q t y).deriv]
rw [he]
exact (((hx t ht').2 x).hasDerivAt.sub (quarticBarrier_space2 ε c Q t x)).deriv
have hvtime (t : ℝ) (ht' : t ∈ Ico 0 Q) (x : ℝ) :
HasDerivWithinAt (fun s => V s x) (vd t x) (Ici t) t := by
convert (ht t ht' x).sub (quarticBarrier_time ε c Q t x).hasDerivWithinAt using 1; first | rfl | (dsimp [V,vd]; ring)
have hvp (t : ℝ) (ht' : t ∈ Ico 0 Q) (x : ℝ) :
0 < vd t x+(1/2:ℝ)*deriv (deriv (V t)) x+b t x*deriv (V t) x := by
have htcc : t ∈ Icc 0 Q := ⟨ht'.1,ht'.2.le⟩
rw [hvxx t htcc x,(hvx t htcc x).deriv]
have hneg := quartic_transport_neg hK (hb t htcc x)
have hneg' := mul_neg_of_pos_of_neg (mul_pos hε (Real.exp_pos (c*(Q-t)))) hneg
have hP := hp t ht' x
dsimp [vd,quarticBarrier,c] at *
nlinarith
intro t ht' x
let R := |x|+C/ε+1
have hdiv : 0 ≤ C/ε := div_nonneg hC hε.le
have hR1 : 1 ≤ R := by dsimp [R]; linarith [abs_nonneg x]
have hR : 0 < R := by linarith
have hxR : x ∈ Icc (-R) R := by
dsimp [R]; constructor <;> linarith [le_abs_self x,neg_abs_le x]
have hCR : C ≤ ε*(1+R^2) := by
have hr : C/ε ≤ 1+R^2 := by dsimp [R] at hR1 ⊢; nlinarith [abs_nonneg x,sq_nonneg R]
have hh := (div_le_iff₀ hε).mp hr
nlinarith
have hB (s : ℝ) (hs : s ∈ Icc 0 Q) :
C*(1+R^2) ≤ quarticBarrier ε c Q s R := by
have he : 1 ≤ Real.exp (c*(Q-s)) :=
Real.one_le_exp_iff.mpr (mul_nonneg hcpos (sub_nonneg.mpr hs.2))
have hh := mul_le_mul_of_nonneg_right hCR (show 0 ≤ 1+R^2 by positivity)
have he' := mul_le_mul_of_nonneg_right he (show 0 ≤ ε*(1+R^2)^2 by positivity)
dsimp [quarticBarrier]
nlinarith
have hVc : ContinuousOn (fun p : ℝ × ℝ => V p.1 p.2) (Icc 0 Q ×ˢ Icc (-R) R) := by
apply (hc.mono (by intro p hp'; exact ⟨hp'.1,mem_univ _⟩)).sub
have hh : Continuous (fun p : ℝ × ℝ => quarticBarrier ε c Q p.1 p.2) := by
unfold quarticBarrier
fun_prop
exact hh.continuousOn
have hcomp := backward_strict_compact (b := b) hQ hR hVc
(fun s hs y => (hvx s hs y).differentiableAt) hvtime (fun s hs y _ => hvp s hs y)
(fun y _ => by
dsimp [V]
have hn : 0 ≤ quarticBarrier ε c Q Q y := by unfold quarticBarrier; positivity
linarith [hterm y])
(fun s hs => by
dsimp [V]
have hh := hg s hs (-R)
have hh' := hB s hs
simp only [neg_sq] at hh
have he : quarticBarrier ε c Q s (-R)=quarticBarrier ε c Q s R := by simp [quarticBarrier]
rw [he]
linarith)
(fun s hs => by dsimp [V]; linarith [hg s hs R,hB s hs])
have hh := hcomp t ht' x hxR
dsimp [V] at hh
linarith
def BackwardComparisonStatement : Prop :=
∀ (Q K C : ℝ), 0 < Q → 0 ≤ K → 0 ≤ C →
∀ (U b d : ℝ → ℝ → ℝ),
ContinuousOn (fun p : ℝ × ℝ => U p.1 p.2) (Icc 0 Q ×ˢ univ) →
(∀ t ∈ Icc 0 Q, Differentiable ℝ (U t) ∧ Differentiable ℝ (deriv (U t))) →
(∀ t ∈ Ico 0 Q, ∀ x, HasDerivWithinAt (fun s => U s x) (d t x) (Ici t) t) →
(∀ t ∈ Icc 0 Q, ∀ x, |b t x| ≤ K*(1+|x|)) →
(∀ t ∈ Icc 0 Q, ∀ x, U t x ≤ C*(1+x^2)) →
(∀ t ∈ Ico 0 Q, ∀ x,
0 ≤ d t x+(1/2:ℝ)*deriv (deriv (U t)) x+b t x*deriv (U t) x) →
(∀ x, U Q x ≤ 0) →
∀ t ∈ Icc 0 Q, ∀ x, U t x ≤ 0
theorem backward_comparison : BackwardComparisonStatement := by
intro Q K C hQ hK hC U b d hc hx ht hb hg hp hterm t ht' x
by_contra hn
have hpos : 0 < U t x := lt_of_not_ge hn
let M := Real.exp ((8*K+8)*(Q-t))*(1+x^2)^2
have hM : 0 < M := by dsimp [M]; positivity
let ε := U t x/(2*M)
have hε : 0 < ε := div_pos hpos (by positivity)
have hh := backward_quartic_bound hQ hK hC hc hx ht hb hg hp hterm hε t ht' x
have he : quarticBarrier ε (8*K+8) Q t x=U t x/2 := by
dsimp only [quarticBarrier]
rw [mul_assoc]
change (U t x/(2*M))*M=U t x/2
field_simp
rw [he] at hh
linarith
end MicroscopicJamming
open Set Filter
open scoped Topology
namespace MicroscopicJamming
def quadraticSourceBarrier (D c Q t x : ℝ) : ℝ :=
D*(Q-t)*Real.exp (c*(Q-t))*(1+x^2)
lemma quadraticSourceBarrier_space (D c Q t x : ℝ) :
HasDerivAt (quadraticSourceBarrier D c Q t)
(D*(Q-t)*Real.exp (c*(Q-t))*(2*x)) x := by
unfold quadraticSourceBarrier
convert ((hasDerivAt_const x 1).add ((hasDerivAt_id x).pow 2)).const_mul
(D*(Q-t)*Real.exp (c*(Q-t))) using 1 <;>
first | rfl | (simp only [id_eq]; ring)
lemma quadraticSourceBarrier_space2 (D c Q t x : ℝ) :
HasDerivAt (deriv (quadraticSourceBarrier D c Q t))
(2*D*(Q-t)*Real.exp (c*(Q-t))) x := by
have he : deriv (quadraticSourceBarrier D c Q t)=
fun y => D*(Q-t)*Real.exp (c*(Q-t))*(2*y) :=
funext fun y => (quadraticSourceBarrier_space D c Q t y).deriv
rw [he]
convert ((hasDerivAt_id x).const_mul 2).const_mul
(D*(Q-t)*Real.exp (c*(Q-t))) using 1 <;> first | rfl | ring
lemma quadraticSourceBarrier_time (D c Q t x : ℝ) :
HasDerivAt (fun s => quadraticSourceBarrier D c Q s x)
(-D*Real.exp (c*(Q-t))*(1+c*(Q-t))*(1+x^2)) t := by
unfold quadraticSourceBarrier
have hs := (hasDerivAt_const t Q).sub (hasDerivAt_id t)
convert (((hs.const_mul D).mul (hs.const_mul c).exp).mul_const (1+x^2)) using 1 <;>
first | rfl | (simp only [Pi.sub_apply,id_eq]; ring)
lemma quadratic_transport_bound {D K Q t x b : ℝ}
(hD : 0 ≤ D) (hK : 0 ≤ K) (ht : t ≤ Q) (hb : |b| ≤ K*(1+|x|)) :
-D*Real.exp ((4*K+2)*(Q-t))*(1+(4*K+2)*(Q-t))*(1+x^2)+
(1/2:ℝ)*(2*D*(Q-t)*Real.exp ((4*K+2)*(Q-t)))+
b*(D*(Q-t)*Real.exp ((4*K+2)*(Q-t))*(2*x)) ≤ -D*(1+x^2) := by
have hnorm : (1+|x|)*|x| ≤ 2*(1+x^2) := by
nlinarith [sq_abs x,sq_nonneg (|x|-1)]
have hbx : b*x ≤ 2*K*(1+x^2) := calc
b*x ≤ |b*x| := le_abs_self _
_ = |b| * |x| := abs_mul _ _
_ ≤ K*(1+|x|)*|x| := mul_le_mul_of_nonneg_right hb (abs_nonneg _)
_ ≤ 2*K*(1+x^2) := by nlinarith [mul_le_mul_of_nonneg_left hnorm hK]
have hpoly : 1+2*b*x-(4*K+2)*(1+x^2) ≤ 0 := by nlinarith [sq_nonneg x]
have he : 1 ≤ Real.exp ((4*K+2)*(Q-t)) :=
Real.one_le_exp_iff.mpr (mul_nonneg (by positivity) (sub_nonneg.mpr ht))
have hx : 0 ≤ 1+x^2 := by positivity
have h1 := mul_nonpos_of_nonneg_of_nonpos
(show 0 ≤ D*(Q-t)*Real.exp ((4*K+2)*(Q-t)) by positivity) hpoly
have h2 := mul_le_mul_of_nonneg_left he (mul_nonneg hD hx)
nlinarith
def BackwardSourceComparisonStatement : Prop :=
∀ (Q K C D : ℝ), 0 < Q → 0 ≤ K → 0 ≤ C → 0 ≤ D →
∀ (U b d : ℝ → ℝ → ℝ),
ContinuousOn (fun p : ℝ × ℝ => U p.1 p.2) (Icc 0 Q ×ˢ univ) →
(∀ t ∈ Icc 0 Q, Differentiable ℝ (U t) ∧ Differentiable ℝ (deriv (U t))) →
(∀ t ∈ Ico 0 Q, ∀ x, HasDerivWithinAt (fun s => U s x) (d t x) (Ici t) t) →
(∀ t ∈ Icc 0 Q, ∀ x, |b t x| ≤ K*(1+|x|)) →
(∀ t ∈ Icc 0 Q, ∀ x, U t x ≤ C*(1+x^2)) →
(∀ t ∈ Ico 0 Q, ∀ x,
-D*(1+x^2) ≤ d t x+(1/2:ℝ)*deriv (deriv (U t)) x+b t x*deriv (U t) x) →
(∀ x, U Q x ≤ 0) →
∀ t ∈ Icc 0 Q, ∀ x, U t x ≤ quadraticSourceBarrier D (4*K+2) Q t x
theorem backward_source_comparison : BackwardSourceComparisonStatement := by
intro Q K C D hQ hK hC hD U b d hc hx ht hb hg hp hterm
let c := 4*K+2
let V : ℝ → ℝ → ℝ := fun t x => U t x-quadraticSourceBarrier D c Q t x
let vd : ℝ → ℝ → ℝ := fun t x => d t x+
D*Real.exp (c*(Q-t))*(1+c*(Q-t))*(1+x^2)
have hvx (t : ℝ) (ht' : t ∈ Icc 0 Q) (x : ℝ) :
HasDerivAt (V t) (deriv (U t) x-D*(Q-t)*Real.exp (c*(Q-t))*(2*x)) x :=
((hx t ht').1 x).hasDerivAt.sub (quadraticSourceBarrier_space D c Q t x)
have hvxx (t : ℝ) (ht' : t ∈ Icc 0 Q) (x : ℝ) :
HasDerivAt (deriv (V t)) (deriv (deriv (U t)) x-2*D*(Q-t)*Real.exp (c*(Q-t))) x := by
have he : deriv (V t)=fun y => deriv (U t) y-deriv (quadraticSourceBarrier D c Q t) y := by
ext y
rw [(hvx t ht' y).deriv,(quadraticSourceBarrier_space D c Q t y).deriv]
rw [he]
exact ((hx t ht').2 x).hasDerivAt.sub (quadraticSourceBarrier_space2 D c Q t x)
have hvtime (t : ℝ) (ht' : t ∈ Ico 0 Q) (x : ℝ) :
HasDerivWithinAt (fun s => V s x) (vd t x) (Ici t) t := by
convert (ht t ht' x).sub (quadraticSourceBarrier_time D c Q t x).hasDerivWithinAt using 1;
first | rfl | (dsimp [V,vd]; ring)
have hvp (t : ℝ) (ht' : t ∈ Ico 0 Q) (x : ℝ) :
0 ≤ vd t x+(1/2:ℝ)*deriv (deriv (V t)) x+b t x*deriv (V t) x := by
have htcc : t ∈ Icc 0 Q := ⟨ht'.1,ht'.2.le⟩
rw [(hvxx t htcc x).deriv,(hvx t htcc x).deriv]
have hneg := quadratic_transport_bound hD hK htcc.2 (hb t htcc x)
have hP := hp t ht' x
dsimp [vd,c] at *
linarith
have hVc : ContinuousOn (fun p : ℝ × ℝ => V p.1 p.2) (Icc 0 Q ×ˢ univ) := by
apply hc.sub
have hh : Continuous (fun p : ℝ × ℝ => quadraticSourceBarrier D c Q p.1 p.2) := by
unfold quadraticSourceBarrier
fun_prop
exact hh.continuousOn
have hVg (t : ℝ) (ht' : t ∈ Icc 0 Q) (x : ℝ) : V t x ≤ C*(1+x^2) := by
have hn : 0 ≤ quadraticSourceBarrier D c Q t x := by
unfold quadraticSourceBarrier
exact mul_nonneg (mul_nonneg (mul_nonneg hD (sub_nonneg.mpr ht'.2))
(Real.exp_pos _).le) (by positivity)
dsimp [V]
linarith [hg t ht' x]
have hVterm (x : ℝ) : V Q x ≤ 0 := by
simpa [V,quadraticSourceBarrier] using hterm x
have hcomp := backward_comparison Q K C hQ hK hC V b vd hVc
(fun t ht' => ⟨fun x => (hvx t ht' x).differentiableAt,
fun x => (hvxx t ht' x).differentiableAt⟩) hvtime hb hVg hvp hVterm
intro t ht' x
have hh := hcomp t ht' x
dsimp [V,c] at hh
linarith
end MicroscopicJamming
open Set Filter
open scoped Topology
namespace MicroscopicJamming
lemma variance_difference_le {Q C L δ : ℝ} (hQ : 0 < Q) (hC : 0 ≤ C)
(hL : 0 ≤ L) (hδ : 0 ≤ δ) {F G : ℝ → ℝ → ℝ} {m n : ℝ → ℝ}
(hcF : ContinuousOn (fun p : ℝ × ℝ => F p.1 p.2) (Icc 0 Q ×ˢ univ))
(hcG : ContinuousOn (fun p : ℝ × ℝ => G p.1 p.2) (Icc 0 Q ×ˢ univ))
(hxF : ∀ t ∈ Icc 0 Q, Differentiable ℝ (F t) ∧ Differentiable ℝ (deriv (F t)))
(hxG : ∀ t ∈ Icc 0 Q, Differentiable ℝ (G t) ∧ Differentiable ℝ (deriv (G t)))
(htF : ∀ t ∈ Ico 0 Q, ∀ x, HasDerivWithinAt (fun s => F s x)
(-(1/2:ℝ)*(deriv (deriv (F t)) x+m t*(deriv (F t) x)^2)) (Ici t) t)
(htG : ∀ t ∈ Ico 0 Q, ∀ x, HasDerivWithinAt (fun s => G s x)
(-(1/2:ℝ)*(deriv (deriv (G t)) x+n t*(deriv (G t) x)^2)) (Ici t) t)
(hm : ∀ t ∈ Icc 0 Q, 0 ≤ m t ∧ m t ≤ 1)
(hclose : ∀ t ∈ Ico 0 Q, |m t-n t| ≤ δ)
(hboundF : ∀ t ∈ Icc 0 Q, ∀ x, |F t x| ≤ C*(1+x^2))
(hboundG : ∀ t ∈ Icc 0 Q, ∀ x, |G t x| ≤ C*(1+x^2))
(hgradF : ∀ t ∈ Icc 0 Q, ∀ x, |deriv (F t) x| ≤ L*(1+|x|))
(hgradG : ∀ t ∈ Icc 0 Q, ∀ x, |deriv (G t) x| ≤ L*(1+|x|))
(hterm : ∀ x, F Q x=G Q x) :
∀ t ∈ Icc 0 Q, ∀ x,
F t x-G t x ≤ quadraticSourceBarrier (δ*L^2) (4*L+2) Q t x := by
let U : ℝ → ℝ → ℝ := fun t x => F t x-G t x
let b : ℝ → ℝ → ℝ := fun t x => m t*(deriv (F t) x+deriv (G t) x)/2
let d : ℝ → ℝ → ℝ := fun t x =>
-(1/2:ℝ)*(deriv (deriv (F t)) x+m t*(deriv (F t) x)^2)-
(-(1/2:ℝ)*(deriv (deriv (G t)) x+n t*(deriv (G t) x)^2))
have hdx (t : ℝ) (ht : t ∈ Icc 0 Q) (x : ℝ) :
HasDerivAt (U t) (deriv (F t) x-deriv (G t) x) x :=
((hxF t ht).1 x).hasDerivAt.sub ((hxG t ht).1 x).hasDerivAt
have hdx2 (t : ℝ) (ht : t ∈ Icc 0 Q) (x : ℝ) :
HasDerivAt (deriv (U t)) (deriv (deriv (F t)) x-deriv (deriv (G t)) x) x := by
have he : deriv (U t)=fun y => deriv (F t) y-deriv (G t) y :=
funext fun y => (hdx t ht y).deriv
rw [he]
exact ((hxF t ht).2 x).hasDerivAt.sub ((hxG t ht).2 x).hasDerivAt
have hc : ContinuousOn (fun p : ℝ × ℝ => U p.1 p.2) (Icc 0 Q ×ˢ univ) := hcF.sub hcG
have hx (t : ℝ) (ht : t ∈ Icc 0 Q) :
Differentiable ℝ (U t) ∧ Differentiable ℝ (deriv (U t)) :=
⟨fun x => (hdx t ht x).differentiableAt,fun x => (hdx2 t ht x).differentiableAt⟩
have htime (t : ℝ) (ht : t ∈ Ico 0 Q) (x : ℝ) :
HasDerivWithinAt (fun s => U s x) (d t x) (Ici t) t := (htF t ht x).sub (htG t ht x)
have hb (t : ℝ) (ht : t ∈ Icc 0 Q) (x : ℝ) : |b t x| ≤ L*(1+|x|) := by
have hsum : |deriv (F t) x+deriv (G t) x| ≤ 2*L*(1+|x|) := by
calc
_ ≤ |deriv (F t) x|+|deriv (G t) x| := abs_add_le _ _
_ ≤ L*(1+|x|)+L*(1+|x|) := add_le_add (hgradF t ht x) (hgradG t ht x)
_ = _ := by ring
have hmul := mul_le_mul_of_nonneg_left hsum (hm t ht).1
have hmul' := mul_le_mul_of_nonneg_right (hm t ht).2 (show 0 ≤ 2*L*(1+|x|) by positivity)
dsimp [b]
rw [abs_div,abs_mul,abs_of_nonneg (hm t ht).1,abs_of_pos (by norm_num : (0:ℝ)<2)]
linarith
have hg (t : ℝ) (ht : t ∈ Icc 0 Q) (x : ℝ) : U t x ≤ (2*C)*(1+x^2) := by
dsimp [U]
have h1 := hboundF t ht x
have h2 := hboundG t ht x
nlinarith [le_abs_self (F t x),neg_abs_le (G t x)]
have hp (t : ℝ) (ht : t ∈ Ico 0 Q) (x : ℝ) :
-(δ*L^2)*(1+x^2) ≤ d t x+(1/2:ℝ)*deriv (deriv (U t)) x+b t x*deriv (U t) x := by
have htcc : t ∈ Icc 0 Q := ⟨ht.1,ht.2.le⟩
rw [(hdx2 t htcc x).deriv,(hdx t htcc x).deriv]
have he : d t x+(1/2:ℝ)*(deriv (deriv (F t)) x-deriv (deriv (G t)) x)+
b t x*(deriv (F t) x-deriv (G t) x)=
-(m t-n t)*(deriv (G t) x)^2/2 := by dsimp [d,b]; ring
rw [he]
have hsquare : (deriv (G t) x)^2 ≤ 2*L^2*(1+x^2) := by
have hs := pow_le_pow_left₀ (abs_nonneg (deriv (G t) x)) (hgradG t htcc x) 2
rw [sq_abs] at hs
have hab : (1+|x|)^2 ≤ 2*(1+x^2) := by nlinarith [sq_abs x,sq_nonneg (|x|-1)]
have hh := mul_le_mul_of_nonneg_left hab (sq_nonneg L)
nlinarith
have h1 := mul_le_mul_of_nonneg_right (abs_le.mp (hclose t ht)).2 (sq_nonneg (deriv (G t) x))
have h2 := mul_le_mul_of_nonneg_left hsquare hδ
nlinarith
have hterm' (x : ℝ) : U Q x ≤ 0 := by simp [U,hterm x]
exact backward_source_comparison Q L (2*C) (δ*L^2) hQ hL (by positivity) (by positivity)
U b d hc hx htime hb hg hp hterm'
end MicroscopicJamming
open MeasureTheory ProbabilityTheory Set Filter
open scoped NNReal Topology
namespace MicroscopicJamming
def GaussianStepStabilityStatement : Prop :=
∀ A B C κ Q : ℝ, 0 < Q → 0 ≤ A → 0 ≤ C → 0 ≤ κ → κ*Q < 1 →
∃ L : ℝ, 0 ≤ L ∧ ∀ u : ℝ → ℝ, RowAnalyticTerminal u A B C κ Q →
∀ rs ss : List (ℝ × ℝ),
(∀ r ∈ rs, 0 ≤ r.1 ∧ r.1 ≤ 1 ∧ 0 ≤ r.2) →
(∀ r ∈ ss, 0 ≤ r.1 ∧ r.1 ≤ 1 ∧ 0 ≤ r.2) →
gaussianStepTime rs=Q → gaussianStepTime ss=Q →
∀ δ : ℝ, 0 ≤ δ →
(∀ t ∈ Icc 0 Q, |gaussianStepCoefficient rs t-gaussianStepCoefficient ss t| ≤ δ) →
∀ t ∈ Icc 0 Q, ∀ x,
|gaussianStepPath rs u t x-gaussianStepPath ss u t x| ≤ δ*L*(1+x^2)
theorem gaussian_step_stability : GaussianStepStabilityStatement := by
intro A B C κ Q hQ hA hC hκ hκQ
obtain ⟨D,L,hD,hL,hpath⟩ := gaussian_step_path A B C κ Q hQ hA hC hκ hκQ
refine ⟨L^2*Q*Real.exp ((4*L+2)*Q),by positivity,?_⟩
intro u hu rs ss hrs hss hTr hTs δ hδ hclose
obtain ⟨_,htermR,htimeR,hspaceR⟩ := hpath u hu rs hrs hTr.le
obtain ⟨_,htermS,htimeS,hspaceS⟩ := hpath u hu ss hss hTs.le
have hxr (t : ℝ) (ht : t ∈ Icc 0 Q) :
Differentiable ℝ (gaussianStepPath rs u t) ∧ Differentiable ℝ (deriv (gaussianStepPath rs u t)) := by
have hh := hspaceR t ht.1 (hTr ▸ ht.2)
exact ⟨hh.1,hh.2.1⟩
have hxs (t : ℝ) (ht : t ∈ Icc 0 Q) :
Differentiable ℝ (gaussianStepPath ss u t) ∧ Differentiable ℝ (deriv (gaussianStepPath ss u t)) := by
have hh := hspaceS t ht.1 (hTs ▸ ht.2)
exact ⟨hh.1,hh.2.1⟩
have hgr (t : ℝ) (ht : t ∈ Icc 0 Q) (x : ℝ) :
|deriv (gaussianStepPath rs u t) x| ≤ L*(1+|x|) :=
((hspaceR t ht.1 (hTr ▸ ht.2)).2.2 x).1
have hgs (t : ℝ) (ht : t ∈ Icc 0 Q) (x : ℝ) :
|deriv (gaussianStepPath ss u t) x| ≤ L*(1+|x|) :=
((hspaceS t ht.1 (hTs ▸ ht.2)).2.2 x).1
have hcr := gaussianStepPath_jointly_continuous hD hL hTr htimeR
(fun t ht htR => ⟨(hspaceR t ht htR).1,fun x => ((hspaceR t ht htR).2.2 x).1⟩)
have hcs := gaussianStepPath_jointly_continuous hD hL hTs htimeS
(fun t ht htS => ⟨(hspaceS t ht htS).1,fun x => ((hspaceS t ht htS).2.2 x).1⟩)
have hpr (t : ℝ) (ht : t ∈ Ico 0 Q) (x : ℝ) :=
gaussianStepPath_right_pde hQ hu hrs hTr.le (hTr ▸ ht) x
have hps (t : ℝ) (ht : t ∈ Ico 0 Q) (x : ℝ) :=
gaussianStepPath_right_pde hQ hu hss hTs.le (hTs ▸ ht) x
have hb : 0 ≤ |B|+A*(1+Q) := by positivity
have hvr (t : ℝ) (ht : t ∈ Icc 0 Q) (x : ℝ) :=
gaussianStepPath_global_value_bound hQ hu hrs hTr ht x
have hvs (t : ℝ) (ht : t ∈ Icc 0 Q) (x : ℝ) :=
gaussianStepPath_global_value_bound hQ hu hss hTs ht x
have hmr (t : ℝ) (_ : t ∈ Icc 0 Q) := gaussianStepRightCoefficient_bounds hrs t
have hms (t : ℝ) (_ : t ∈ Icc 0 Q) := gaussianStepRightCoefficient_bounds hss t
have hδr (t : ℝ) (ht : t ∈ Ico 0 Q) := gaussianStepRightCoefficient_close hclose ht
have hδs (t : ℝ) (ht : t ∈ Ico 0 Q) :
|gaussianStepRightCoefficient ss t-gaussianStepRightCoefficient rs t| ≤ δ := by
rw [abs_sub_comm]
exact hδr t ht
have hterm (x : ℝ) : gaussianStepPath rs u Q x=gaussianStepPath ss u Q x := by
simpa only [hTr,hTs] using (htermR x).trans (htermS x).symm
have hr := variance_difference_le hQ hb hL hδ hcr hcs hxr hxs hpr hps hmr hδr hvr hvs hgr hgs hterm
have hs := variance_difference_le hQ hb hL hδ hcs hcr hxs hxr hps hpr hms hδs hvs hvr hgs hgr
(fun x => (hterm x).symm)
intro t ht x
have hab : |gaussianStepPath rs u t x-gaussianStepPath ss u t x| ≤
quadraticSourceBarrier (δ*L^2) (4*L+2) Q t x := by
rw [abs_le]
constructor
· linarith [hs t ht x]
· exact hr t ht x
have he : Real.exp ((4*L+2)*(Q-t)) ≤ Real.exp ((4*L+2)*Q) :=
Real.exp_le_exp.mpr (mul_le_mul_of_nonneg_left (by linarith [ht.1]) (by positivity))
have htq : (Q-t)*Real.exp ((4*L+2)*(Q-t)) ≤ Q*Real.exp ((4*L+2)*Q) :=
mul_le_mul (by linarith [ht.1]) he (Real.exp_pos _).le hQ.le
calc
_ ≤ quadraticSourceBarrier (δ*L^2) (4*L+2) Q t x := hab
_ = (δ*L^2)*((Q-t)*Real.exp ((4*L+2)*(Q-t)))*(1+x^2) := by
unfold quadraticSourceBarrier
ring
_ ≤ (δ*L^2)*(Q*Real.exp ((4*L+2)*Q))*(1+x^2) :=
mul_le_mul_of_nonneg_right (mul_le_mul_of_nonneg_left htq (by positivity)) (by positivity)
_ = δ*(L^2*Q*Real.exp ((4*L+2)*Q))*(1+x^2) := by ring
end MicroscopicJamming
namespace MicroscopicJamming
def GaussianStepThirdStatement : Prop :=
∀ (u : ℝ → ℝ) (A B C κ Q : ℝ), 0 < Q → RowAnalyticTerminal u A B C κ Q →
∃ H : ℝ, 0 ≤ H ∧
∀ rs : List (ℝ × ℝ), (∀ r ∈ rs, 0 ≤ r.1 ∧ r.1 ≤ 1 ∧ 0 ≤ r.2) →
gaussianStepTime rs ≤ Q → ∀ t : ℝ, 0 ≤ t → t ≤ gaussianStepTime rs →
Differentiable ℝ (deriv (deriv (gaussianStepPath rs u t))) ∧
∀ x, |deriv (deriv (deriv (gaussianStepPath rs u t))) x| ≤ H
end MicroscopicJamming
end
end OAI