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import Mathlib
import OAI.Geometry.BallPacking.Moduli.SmoothZeroCharts
namespace OAI
noncomputable section
namespace HigherDimensionalBallPacking.Rigidity
section
open scoped ContDiff Topology
open Set Function Filter
variable {X Y : Type*} [NormedAddCommGroup X] [NormedSpace ℝ X]
[NormedAddCommGroup Y] [NormedSpace ℝ Y]
def freezeTime (t : ℝ) : ℝ := Real.smoothTransition (2*t-1/2)
def frozenPath (F : ℝ × X → Y) (v : ℝ × X) : Y := F (freezeTime v.1,v.2)
lemma freezeTime_smooth : ContDiff ℝ ∞ freezeTime :=
(show ContDiff ℝ ∞ Real.smoothTransition from contDiff_infty.mpr (fun _ => Real.smoothTransition.contDiff)).comp
((contDiff_const.mul contDiff_id).sub contDiff_const)
lemma freezeTime_mem (t : ℝ) : freezeTime t∈Icc (0:ℝ) 1 :=
⟨Real.smoothTransition.nonneg _,Real.smoothTransition.le_one _⟩
lemma freezeTime_initial {t : ℝ} (ht : t≤1/4) : freezeTime t=0 :=
Real.smoothTransition.zero_of_nonpos (by linarith)
lemma freezeTime_final {t : ℝ} (ht : 3/4≤t) : freezeTime t=1 :=
Real.smoothTransition.one_of_one_le (by linarith)
lemma frozenPath_smooth {F : ℝ × X → Y} (hF : ContDiff ℝ ∞ F) : ContDiff ℝ ∞ (frozenPath F) :=
hF.comp ((freezeTime_smooth.comp contDiff_fst).prodMk contDiff_snd)
lemma ProperIndexZeroPath.frozen {F : ℝ × X → Y} {U : Set X} (h : ProperIndexZeroPath F U) :
ProperIndexZeroPath (frozenPath F) U := by
let K := Prod.snd '' {v : ℝ × X | v.1∈Icc (0:ℝ) 1 ∧ v.2∈U ∧ F v=0}
have hK : IsCompact K := h.zeroSet_compact.image continuous_snd
have hKU : K⊆U := by rintro x ⟨v,hv,rfl⟩; exact hv.2.1
have he : {v : ℝ × X | v.1∈Icc (0:ℝ) 1 ∧ v.2∈U ∧ frozenPath F v=0} =
(Icc (0:ℝ) 1 ×ˢ K) ∩ {v | frozenPath F v=0} := by
ext v
constructor
· rintro ⟨ht,hx,hz⟩
exact ⟨⟨ht,⟨(freezeTime v.1,v.2),⟨freezeTime_mem _,hx,hz⟩,rfl⟩⟩,hz⟩
· rintro ⟨⟨ht,hx⟩,hz⟩
exact ⟨ht,hKU hx,hz⟩
refine ⟨h.domain_open,h.origin_mem,frozenPath_smooth h.smooth,?_,?_,?_⟩
· obtain ⟨L,hL⟩ := h.initial
refine ⟨L,fun x => ?_⟩
change F (freezeTime 0,x)=L x
rw [freezeTime_initial (by norm_num)]
exact hL x
· rw [he]
exact (isCompact_Icc.prod hK).inter_right (isClosed_eq (frozenPath_smooth h.smooth).continuous continuous_const)
· intro t ht x hx
exact h.fredholm _ (freezeTime_mem t) x hx
end
section
open scoped ContDiff Topology
open Set Function Filter
variable {X Y : Type*} [NormedAddCommGroup X] [NormedSpace ℝ X] [CompleteSpace X]
[NormedAddCommGroup Y] [NormedSpace ℝ Y] [CompleteSpace Y]
variable {F : ℝ × X → Y} {E : Submodule ℝ Y} [FiniteDimensional ℝ E]
(L : X ≃L[ℝ] Y) (hL : ∀ x,F (0,x)=L x)
def frozenInitialChart : ZeroGraphChart (finiteTargetAugment (frozenPath F) E) E where
base := (0,(0,0))
zero_base := by
change F (freezeTime 0,0)+(0:Y)=0
rw [freezeTime_initial (by norm_num),hL,map_zero,add_zero]
coordinate := ContinuousLinearMap.snd ℝ X E
reconstruct q := initialKernelGraph L E q.2
domain := {q | q.1<1/4}
ambient := {v | v.1<1/4}
domain_open := isOpen_lt continuous_fst continuous_const
ambient_open := isOpen_lt continuous_fst continuous_const
base_domain := by norm_num
base_ambient := by norm_num
smooth := ((initialKernelGraph L E).contDiff.comp contDiff_snd).contDiffOn
left_inv q := rfl
zero q hq := by
change F (freezeTime q.1,-L.symm (q.2:Y))+(q.2:Y)=0
rw [freezeTime_initial (le_of_lt hq),hL,map_neg,L.apply_symm_apply,neg_add_cancel]
image_ambient q hq := hq
complete v hv hz := by
change initialKernelGraph L E v.2.2=v.2
apply (initialKernelGraph_kernel v.2).mp
change F (freezeTime v.1,v.2.1)+(v.2.2:Y)=0 at hz
rwa [freezeTime_initial (le_of_lt hv),hL] at hz
omit [FiniteDimensional ℝ E] in
lemma frozenInitialChart_smooth [FiniteDimensional ℝ E] : ContDiff ℝ ∞ (frozenInitialChart L hL (E := E)).reconstruct :=
(initialKernelGraph L E).contDiff.comp contDiff_snd
omit [FiniteDimensional ℝ E] in
lemma frozenInitialChart_source [FiniteDimensional ℝ E]
(v : {v : ℝ × (X × E) // finiteTargetAugment (frozenPath F) E v=0}) :
v∈(frozenInitialChart L hL).partialHomeomorph.source ↔ v.val.1<1/4 := by
change (v.val.1<1/4 ∧ v.val.1<1/4) ↔ _
simp
omit [FiniteDimensional ℝ E] in
lemma frozenInitialChart_spatialDerivative [FiniteDimensional ℝ E] (q : ℝ × E) :
(frozenInitialChart L hL (E := E)).spatialDerivative q=initialKernelGraph L E := by
change (fderiv ℝ (fun q : ℝ × E => initialKernelGraph L E q.2) q).comp _=_
have hd := (initialKernelGraph L E).hasFDerivAt.comp q (hasFDerivAt_snd (p := q))
simp only [Function.comp_def] at hd
rw [hd.fderiv]
ext e <;> rfl
end
section
open scoped ContDiff Topology
open Set Function Filter
variable {X Y E : Type*} [NormedAddCommGroup X] [NormedSpace ℝ X]
[NormedAddCommGroup Y] [NormedSpace ℝ Y]
[NormedAddCommGroup E] [NormedSpace ℝ E] {F : ℝ × X → Y}
def ZeroGraphChart.rebase (c : ZeroGraphChart F E) (p : {v : ℝ × X // F v=0})
(hp : p∈c.partialHomeomorph.source) : ZeroGraphChart F E :=
{c with base := p.val,zero_base := p.property,base_domain := hp.2,base_ambient := hp.1}
def SmoothZeroAtlas.prescribe {s : TopologicalSpace.Opens {v : ℝ × X // F v=0}}
(a : SmoothZeroAtlas F E s) (p : s) (c : ZeroGraphChart F E)
(hp : p.val∈c.partialHomeomorph.source) (hc : ContDiffOn ℝ ∞ c.reconstruct c.domain) :
SmoothZeroAtlas F E s := by
classical
refine {chart := fun x => if x=p then c.rebase p.val hp else a.chart x,base := ?_,smooth := ?_}
· intro x
by_cases hx : x=p
· subst x; simp only; rfl
· simp only [ite_eq_right hx]; exact a.base x
· intro x
by_cases hx : x=p
· simp only [ite_eq_left hx]; exact hc
· simp only [ite_eq_right hx]; exact a.smooth x
@[simp] lemma SmoothZeroAtlas.prescribe_at {s : TopologicalSpace.Opens {v : ℝ × X // F v=0}}
(a : SmoothZeroAtlas F E s) (p : s) (c : ZeroGraphChart F E)
(hp : p.val∈c.partialHomeomorph.source) (hc : ContDiffOn ℝ ∞ c.reconstruct c.domain) :
(a.prescribe p c hp hc).chart p=c.rebase p.val hp := by
classical
simp [SmoothZeroAtlas.prescribe]
end
section
open scoped ContDiff Topology
open Set Function Filter
variable {X Y : Type*} [NormedAddCommGroup X] [NormedSpace ℝ X] [CompleteSpace X]
[NormedAddCommGroup Y] [NormedSpace ℝ Y] [CompleteSpace Y]
theorem ProperIndexZeroPath.smooth_framed_isolating_stabilization
{F : ℝ × X → Y} {U : Set X} (h : ProperIndexZeroPath F U) :
∃ E : Submodule ℝ Y,∃ _ : FiniteDimensional ℝ E,
∃ V : Set (ℝ × X),IsOpen V ∧
∃ _ : StabilizedKernelFrame F E V,
∃ N : Set (ℝ × (X × E)),IsolatingStabilization F U E N ∧
(∀ v∈closure N,finiteTargetAugment F E v=0 →(v.1,v.2.1)∈V) ∧
(∀ v∈V,Surjective ((pathSpatialDerivative F v).coprod E.subtypeL)) := by
obtain ⟨K,hK,hKU,h0K,hZ,E,hE,V,hVo,hKV,hs,⟨fr⟩⟩ := h.stabilized_kernel_frame
let := hE
let B : ℝ × X → ℝ × (X × E) := fun v => (v.1,(v.2,0))
have hB : Continuous B := continuous_fst.prodMk (continuous_snd.prodMk continuous_const)
let Z := B '' {v : ℝ × X | v.1∈Icc (0:ℝ) 1 ∧ v.2∈U ∧ F v=0}
let W : Set (ℝ × (X × E)) := {v | v.2.1∈U ∧ (v.1,v.2.1)∈V}
have hZc : IsCompact Z := h.zeroSet_compact.image hB
have hWo : IsOpen W := (h.domain_open.preimage (continuous_fst.comp continuous_snd)).inter
(hVo.preimage (continuous_fst.prodMk (continuous_fst.comp continuous_snd)))
have hZW : Z⊆W := by
rintro _ ⟨⟨t,x⟩,hv,rfl⟩
exact ⟨hv.2.1,hKV ⟨hv.1,hZ t hv.1 x hv.2.1 hv.2.2⟩⟩
have hg (v : ℝ × (X × E)) (hv : v∈W) (hz : finiteTargetAugment F E v=0) :
Nonempty (FiniteZeroGerm (finiteTargetAugment F E) v.1 v.2 (Module.finrank ℝ E)) :=
fr.zero_germ h.smooth hv.2 (hs _ hv.2) hz
have hcharts : ∀ v∈Z,∃ m,Nonempty (FiniteZeroGerm (finiteTargetAugment F E) v.1 v.2 m) := by
intro v hv
refine ⟨Module.finrank ℝ E,hg v (hZW hv) ?_⟩
rcases hv with ⟨⟨t,x⟩,hv,rfl⟩
simpa only [B,finiteTargetAugment,ZeroMemClass.coe_zero,add_zero] using hv.2.2
obtain ⟨N,hNo,hZN,hNc,hNW⟩ := compact_zero_isolating_neighborhood
(finiteTargetAugment_smooth h.smooth E).continuous hZc hWo hZW hcharts
refine ⟨E,hE,V,hVo,fr,N,⟨hNo,?_,hNc,?_,?_⟩,?_,?_⟩
· intro t ht x hx hz
exact hZN ⟨(t,x),⟨ht,hx,hz⟩,rfl⟩
· intro v hv hz
exact (hNW ⟨hv,hz⟩).1
· intro v hv ht hz
exact hg v (hNW ⟨hv,hz⟩) hz
· intro v hv hz
exact (hNW ⟨hv,hz⟩).2
· exact hs
end
section
open scoped ContDiff Topology
open Set Function Filter
variable {X Y : Type*} [NormedAddCommGroup X] [NormedSpace ℝ X] [CompleteSpace X]
[NormedAddCommGroup Y] [NormedSpace ℝ Y] [CompleteSpace Y]
variable {F : ℝ × X → Y} {U : Set X} {E : Submodule ℝ Y} [FiniteDimensional ℝ E]
{N : Set (ℝ × (X × E))}
omit [CompleteSpace X] [CompleteSpace Y] in
lemma IsolatingStabilization.small_frozen_final_collar [CompleteSpace X] [CompleteSpace Y]
(h : IsolatingStabilization (frozenPath F) U E N) (hn : ∀ x∈U,F (1,x)≠0) :
∃ δ : ℝ,0<δ ∧ ∀ v∈closure N,3/4≤v.1 →‖v.2.2‖≤δ →
finiteTargetAugment (frozenPath F) E v≠0 := by
let C := (closure N ∩ {v | finiteTargetAugment (frozenPath F) E v=0}) ∩ {v | 3/4≤v.1}
have hC : IsCompact C := h.compact.inter_right (isClosed_le continuous_const continuous_fst)
let B := (fun v : ℝ × (X × E) => v.2.2) '' C
have hB : IsCompact B := hC.image (continuous_snd.comp continuous_snd)
have hB0 : (0:E)∉B := by
rintro ⟨⟨t,x,e⟩,⟨⟨hcl,hz⟩,ht⟩,he⟩
have he0 : e=0 := he
subst e
have hx := h.domain (t,(x,0)) hcl hz
change F (freezeTime t,x)+(0:Y)=0 at hz
rw [freezeTime_final ht,add_zero] at hz
exact hn x hx hz
obtain ⟨r,hr,hrB⟩ := Metric.isOpen_iff.mp hB.isClosed.isOpen_compl 0 hB0
refine ⟨r/2,half_pos hr,?_⟩
intro v hv ht he hz
apply hrB (show v.2.2∈Metric.ball 0 r from ?_) ⟨v,⟨⟨hv,hz⟩,ht⟩,rfl⟩
simpa only [Metric.mem_ball,dist_zero_right] using he.trans_lt (half_lt_self hr)
omit [CompleteSpace X] [CompleteSpace Y] in
lemma IsolatingStabilization.small_frozen_initial_collar [CompleteSpace X] [CompleteSpace Y]
(h : IsolatingStabilization (frozenPath F) U E N) (hp : ProperIndexZeroPath F U)
(L : X ≃L[ℝ] Y) (hL : ∀ x,F (0,x)=L x) :
∃ δ : ℝ,0<δ ∧ ∀ t∈Icc (0:ℝ) (1/4),∀ e : E,‖e‖≤δ →
(t,(-L.symm (e:Y),e))∈N := by
let ψ : ℝ × E → ℝ × (X × E) := fun v => (v.1,(-L.symm (v.2:Y),v.2))
have hψ : Continuous ψ := continuous_fst.prodMk
((L.symm.continuous.comp (E.subtypeL.continuous.comp continuous_snd)).neg.prodMk continuous_snd)
let K : Set (ℝ × E) := Icc (0:ℝ) (1/4) ×ˢ {0}
have hK : IsCompact K := isCompact_Icc.prod isCompact_singleton
have hKN : K⊆ψ ⁻¹' N := by
rintro ⟨t,e⟩ ⟨ht,he⟩
have he0 : e=0 := he
subst e
have hz : frozenPath F (t,0)=0 := by
change F (freezeTime t,0)=0
rw [freezeTime_initial ht.2,hL,map_zero]
change (t,(-L.symm ((0:E):Y),0))∈N
simpa only [ZeroMemClass.coe_zero,map_zero,neg_zero] using
h.contains t ⟨ht.1,ht.2.trans (by norm_num)⟩ 0 hp.origin_mem hz
obtain ⟨r,hr,hrN⟩ := hK.exists_cthickening_subset_open (h.isOpen.preimage hψ) hKN
refine ⟨r/2,half_pos hr,?_⟩
intro t ht e he
change (t,e)∈ψ ⁻¹' N
apply hrN
apply Metric.mem_cthickening_of_dist_le (t,e) (t,0) r K ⟨ht,rfl⟩
simpa [Prod.dist_eq,dist_zero_right] using he.trans (half_le_self (le_of_lt hr))
omit [CompleteSpace X] [CompleteSpace Y] in
lemma IsolatingStabilization.small_target_reservoir [CompleteSpace X] [CompleteSpace Y]
(h : IsolatingStabilization F U E N) {δ : ℝ}
(hδ : ∀ v∈frontier N,v.1∈Icc (0:ℝ) 1 →‖v.2.2‖≤δ →finiteTargetAugment F E v≠0) :
let K := (closure N ∩ {v | finiteTargetAugment F E v=0}) ∩
{v | v.1∈Icc (0:ℝ) 1 ∧ ‖v.2.2‖≤δ}
IsCompact K ∧ K⊆N := by
dsimp only
refine ⟨h.compact.inter_right ?_,?_⟩
· exact (isClosed_Icc.preimage continuous_fst).inter
(isClosed_le ((continuous_snd.comp continuous_snd).norm) continuous_const)
· intro v hv
by_contra hn
have hf : v∈frontier N := by
rw [h.isOpen.frontier_eq]
exact ⟨hv.1.1,hn⟩
exact hδ v hf hv.2.1 hv.2.2 hv.1.2
end
section
open scoped ContDiff Topology
open Set Function Filter
variable {X Y : Type*} [NormedAddCommGroup X] [NormedSpace ℝ X] [CompleteSpace X]
[NormedAddCommGroup Y] [NormedSpace ℝ Y] [CompleteSpace Y]
lemma orientedZeroAtlas_self_source {F : ℝ × X → Y} {E : Submodule ℝ Y}
[FiniteDimensional ℝ E] {V : Set (ℝ × X)} (fr : StabilizedKernelFrame F E V)
(hF : ContDiff ℝ ∞ F) (hV : IsOpen V)
(a : SmoothZeroAtlas (finiteTargetAugment F E) E (framedZeroOpen F E V hV))
(x : framedZeroOpen F E V hV) : x∈((fr.orientedZeroAtlas hF hV a).chart x).source := by
change x∈(((a.localChart x).symm.restrOpen _ _).symm).source
refine ⟨a.chartedSpace.mem_chart_source x,?_⟩
exact (framedChart_orientation_neighborhood fr (a.chart x) hF hV
(a.localChart_target x (framedLocalChart_base_target hV a x))
(framedLocalChart_V hV a x (framedLocalChart_base_target hV a x))).choose_spec.2.1
theorem ProperIndexZeroPath.endpoint_exists {F : ℝ × X → Y} {U : Set X}
(h : ProperIndexZeroPath F U) : ∃ x∈U,F (1,x)=0 := by
classical
by_contra hn
push Not at hn
obtain ⟨E,hE,V,hV,fr,N,hN,hNV,hs⟩ := h.frozen.smooth_framed_isolating_stabilization
let := hE
obtain ⟨L,hL⟩ := h.initial
let A := finiteTargetAugment (frozenPath F) E
let M := framedZeroOpen (frozenPath F) E V hV
let base : ℝ × (X × E) := ((1:ℝ)/8,(0,0))
have hbz : A base=0 := by
change F (freezeTime (1/8),0)+(0:Y)=0
rw [freezeTime_initial (by norm_num),hL,map_zero,add_zero]
have hbN : base∈N := by
apply hN.contains (1/8) (by constructor <;> norm_num) 0 h.origin_mem
change F (freezeTime (1/8),0)=0
rw [freezeTime_initial (by norm_num),hL,map_zero]
let p : M := ⟨⟨base,hbz⟩,hNV base (subset_closure hbN) hbz⟩
let c := frozenInitialChart L hL (E := E)
have hpC : p.val∈c.partialHomeomorph.source := by
apply (frozenInitialChart_source L hL p.val).mpr
norm_num [p,base]
let a₀ := fr.smoothZeroAtlas (frozenPath_smooth h.smooth) hV hs
let a := a₀.prescribe p c hpC (frozenInitialChart_smooth L hL).contDiffOn
let atlas := fr.orientedZeroAtlas (frozenPath_smooth h.smooth) hV a
let π := fr.physicalProjection (frozenPath_smooth h.smooth) hV a
have hπ (z : M) : π.map z=(z.val.val.1,z.val.val.2.2) := rfl
have hπc : Continuous π.map := (continuous_fst.comp (continuous_subtype_val.comp continuous_subtype_val)).prodMk
(continuous_snd.comp (continuous_snd.comp (continuous_subtype_val.comp continuous_subtype_val)))
have hpi : p∈(atlas.chart p).source := orientedZeroAtlas_self_source fr (frozenPath_smooth h.smooth) hV a p
have hπp : π.map p=((1:ℝ)/8,0) := rfl
have hac : a.chart p=c.rebase p.val hpC := a₀.prescribe_at p c hpC (frozenInitialChart_smooth L hL).contDiffOn
have hid : EqOn (π.map ∘ (atlas.chart p).symm) id (atlas.chart p).target := by
intro q hq
change ((((a.localChart p).symm q).val.val).1,(((a.localChart p).symm q).val.val).2.2)=q
rw [a.localChart_symm_val p (orientedZeroAtlas_target fr (frozenPath_smooth h.smooth) hV a p hq),hac]
rfl
have hint : ∀ q∈(atlas.chart p).target,q.1<1/4 := by
intro q hq
have hh := a.localChart_target p (orientedZeroAtlas_target fr (frozenPath_smooth h.smooth) hV a p hq)
rw [hac] at hh
exact hh
have hinj : ∀ x y : M,(π.map x).1<1/4 →(π.map y).1<1/4 →π.map x=π.map y →x=y := by
intro x y hx hy he
have hxx : initialKernelGraph L E x.val.val.2.2=x.val.val.2 := c.complete x.val.val hx x.val.property
have hyy : initialKernelGraph L E y.val.val.2.2=y.val.val.2 := c.complete y.val.val hy y.val.property
apply Subtype.ext
apply Subtype.ext
apply Prod.ext
· exact congrArg (fun v : ℝ × E => v.1) he
· exact hxx.symm.trans ((congrArg (initialKernelGraph L E) (congrArg Prod.snd he)).trans hyy)
let N₀ : Set M := {z | z.val.val∈N}
have hN₀ : IsOpen N₀ := hN.isOpen.preimage (continuous_subtype_val.comp continuous_subtype_val)
have hpN₀ : p∈N₀ := hbN
obtain ⟨δB,hδB,havoid⟩ := hN.small_target_boundary_avoid
obtain ⟨δF,hδF,hfinal⟩ := hN.small_frozen_final_collar hn
let δ₀ := min δB δF
have hδ₀ : 0<δ₀ := lt_min hδB hδF
have hcompact : ∀ δ : ℝ,0<δ →δ≤δ₀ →IsCompact {z : M | z∈N₀ ∧
(π.map z).1∈Icc (0:ℝ) 1 ∧ ‖(π.map z).2‖≤δ} := by
intro δ hδ hd
have hsmall : ∀ v∈frontier N,v.1∈Icc (0:ℝ) 1 →‖v.2.2‖≤δ →A v≠0 := by
intro v hv ht he
exact havoid v hv ht (he.trans (hd.trans (min_le_left _ _)))
have hc := hN.small_target_reservoir hsmall
let C : Set (ℝ × (X × E)) := (closure N ∩ {v | A v=0}) ∩
{v | v.1∈Icc (0:ℝ) 1 ∧ ‖v.2.2‖≤δ}
have hCc : IsCompact C := hc.1
have hCN : C⊆N := hc.2
let val : M → ℝ × (X × E) := fun z => z.val.val
have hval : Topology.IsEmbedding val := Topology.IsEmbedding.subtypeVal.comp Topology.IsEmbedding.subtypeVal
have hCrange : C⊆range val := by
intro v hv
exact ⟨⟨⟨v,hv.1.2⟩,hNV v hv.1.1 hv.1.2⟩,rfl⟩
have hpre := (hval.isCompact_preimage_iff hCrange).mpr hCc
have he : val ⁻¹' C={z : M | z∈N₀ ∧ (π.map z).1∈Icc (0:ℝ) 1 ∧ ‖(π.map z).2‖≤δ} := by
ext z
constructor
· intro hz
exact ⟨hCN hz,hz.2⟩
· rintro ⟨hz,ht,he⟩
exact ⟨⟨subset_closure hz,z.val.property⟩,ht,he⟩
rwa [he] at hpre
have hfinal₀ : ∀ z∈N₀,3/4≤(π.map z).1 →‖(π.map z).2‖≤δ₀ →False := by
intro z hz ht he
exact hfinal z.val.val (subset_closure hz) ht (he.trans (min_le_right _ _)) z.val.property
exact Degree.isolated_collar_impossible atlas π hπc p p hpi hπp hid hint hinj N₀ hN₀ hpN₀
δ₀ hδ₀ hcompact hfinal₀
end
end HigherDimensionalBallPacking.Rigidity
end
end OAI