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import OAI.Combinatorics.CycleDecomposition.CycleLifting
namespace OAI
universe cycleUniverse1 cycleUniverse2 cycleUniverse3 cycleUniverse4 cycleUniverse5 cycleUniverse6 cycleUniverse7 cycleUniverse8 cycleUniverse9 cycleUniverse10 cycleUniverse11 cycleUniverse12
section
open Filter Asymptotics Real
open scoped Topology
noncomputable section
open MeasureTheory ProbabilityTheory Finset
section
namespace ErdosGallai.Batch
noncomputable section
open Finset SimpleGraph
attribute [local instance] Classical.propDecidable
def demandLoad {I : Type cycleUniverse1} {V : Type cycleUniverse2} [Fintype I] (x y : I → V) (v : V) : ℕ :=
(univ.filter fun i => x i = v ∨ y i = v).card
theorem demand_load_le_degree {V : Type cycleUniverse3} {I : Type cycleUniverse4} {B : Type cycleUniverse5} [Fintype V] [Fintype I]
[DecidableEq V] (G : SimpleGraph V) [DecidableRel G.Adj]
(E : B → Set (Sym2 V))
(hE : Pairwise fun b c => Disjoint (E b) (E c))
(owner : I → B) (x y : I → V)
(hunique : ∀ i j v, owner i = owner j →
(x i = v ∨ y i = v) → (x j = v ∨ y j = v) → i = j)
(hedge : ∀ i v, x i = v ∨ y i = v →
∃ w, G.Adj v w ∧ s(v,w) ∈ E (owner i)) (v : V) :
demandLoad x y v ≤ G.degree v := by
classical
let S := {i : I // x i = v ∨ y i = v}
have hs (i : S) := hedge i.val v i.property
let f : S → G.neighborFinset v := fun i =>
⟨(hs i).choose, by simpa using (hs i).choose_spec.1⟩
have hf : Function.Injective f := by
intro i j hij
have he : (hs i).choose = (hs j).choose := congrArg Subtype.val hij
apply Subtype.ext
by_cases ho : owner i.val = owner j.val
· exact hunique i.val j.val v ho i.property j.property
· exact False.elim (Set.disjoint_left.mp (hE ho)
(hs i).choose_spec.2 (by rw [he]; exact (hs j).choose_spec.2))
have hc := Fintype.card_le_of_injective f hf
have hn : Fintype.card (G.neighborFinset v) = G.degree v := by
rw [Fintype.card_coe, SimpleGraph.card_neighborFinset_eq_degree]
rw [hn] at hc
have hcS : Fintype.card S = demandLoad x y v := by
simp only [S, Fintype.card_subtype, demandLoad]
congr 1
ext i
simp
rw [hcS] at hc
exact hc
lemma start_has_incident_edge {V : Type cycleUniverse6} {G : SimpleGraph V} {a b : V}
(p : G.Walk a b) (hp : ¬p.Nil) :
∃ w, G.Adj a w ∧ s(a,w) ∈ p.edgeSet := by
exact ⟨p.snd,p.adj_snd hp,p.mk_start_snd_mem_edges hp⟩
lemma finish_has_incident_edge {V : Type cycleUniverse7} {G : SimpleGraph V} {a b : V}
(p : G.Walk a b) (hp : ¬p.Nil) :
∃ w, G.Adj b w ∧ s(b,w) ∈ p.edgeSet := by
refine ⟨p.penultimate,(p.adj_penultimate hp).symm,?_⟩
change s(b,p.penultimate) ∈ p.edges
simpa only [Sym2.eq_swap] using p.mk_penultimate_end_mem_edges hp
theorem path_demands_load_le_degree {V : Type cycleUniverse8} {I : Type cycleUniverse9} [Fintype V] [Fintype I]
[DecidableEq V] (G : SimpleGraph V) [DecidableRel G.Adj]
(x y : I → V) (p : ∀ i, G.Walk (x i) (y i))
(hpos : ∀ i, ¬(p i).Nil)
(hd : Pairwise fun i j => Disjoint (p i).edgeSet (p j).edgeSet) (v : V) :
demandLoad x y v ≤ G.degree v := by
apply demand_load_le_degree G (fun i => (p i).edgeSet) hd id x y
· intro i j _ hij _ _; exact hij
· intro i w hw
rcases hw with rfl | rfl
· exact start_has_incident_edge (p i) (hpos i)
· exact finish_has_incident_edge (p i) (hpos i)
lemma disjoint_sum_blocks {α : Type cycleUniverse10} {B : Type cycleUniverse11} {C : Type cycleUniverse12} (E : B → Set α) (F : C → Set α)
(hE : Pairwise fun b c => Disjoint (E b) (E c))
(hF : Pairwise fun b c => Disjoint (F b) (F c))
(hEF : ∀ b c, Disjoint (E b) (F c)) :
Pairwise (fun i j : B ⊕ C => Disjoint (Sum.elim E F i) (Sum.elim E F j)) := by
intro i j hij
cases i with
| inl b =>
cases j with
| inl c => exact hE (fun he => hij (congrArg Sum.inl he))
| inr c => exact hEF b c
| inr b =>
cases j with
| inl c => exact (hEF c b).symm
| inr c => exact hF (fun he => hij (congrArg Sum.inr he))
end
end ErdosGallai.Batch
namespace ErdosGallai.Batch
def CycleOrSingleEdge {V : Type} (G : SimpleGraph V)
(s : Set (Sym2 V)) : Prop :=
(∃ (v : V) (p : G.Walk v v), p.IsCycle ∧ s = p.edgeSet) ∨
∃ e ∈ G.edgeSet, s = {e}
def EdgeDecomposition {V : Type} (G : SimpleGraph V) (k : ℕ) : Prop :=
∃ parts : Fin k → Set (Sym2 V),
(∀ i, CycleOrSingleEdge G (parts i)) ∧
Pairwise (fun i j => Disjoint (parts i) (parts j)) ∧
(⋃ i, parts i) = G.edgeSet
noncomputable section
open SimpleGraph
lemma cycleOrSingleEdge_subset {V : Type} {G : SimpleGraph V}
{s : Set (Sym2 V)} (hs : CycleOrSingleEdge G s) : s ⊆ G.edgeSet := by
rcases hs with ⟨v,p,hp,rfl⟩ | ⟨e,he,rfl⟩
· exact p.edges_subset_edgeSet
· simpa using he
lemma cycleOrSingleEdge_map {V W : Type} {G : SimpleGraph V} {H : SimpleGraph W}
(f : G →g H) (hf : Function.Injective f) {s : Set (Sym2 V)}
(hs : CycleOrSingleEdge G s) : CycleOrSingleEdge H (Sym2.map f '' s) := by
rcases hs with ⟨v,p,hp,rfl⟩ | ⟨e,he,rfl⟩
· exact Or.inl ⟨f v,p.map f,hp.map hf,(p.edgeSet_map f).symm⟩
· refine Or.inr ⟨Sym2.map f e, ?_, by simp⟩
induction e using Sym2.ind with | _ x y =>
exact f.map_adj he
lemma edgeDecomposition_of_indexed {V I : Type} [Fintype I] (G : SimpleGraph V)
(parts : I → Set (Sym2 V)) (hp : ∀ i, CycleOrSingleEdge G (parts i))
(hd : Pairwise (fun i j => Disjoint (parts i) (parts j)))
(hu : (⋃ i, parts i) = G.edgeSet) : EdgeDecomposition G (Fintype.card I) := by
let e := Fintype.equivFin I
refine ⟨fun j => parts (e.symm j), fun j => hp _, ?_, ?_⟩
· intro i j hij
exact hd (fun he => hij (e.symm.injective he))
· ext x
simp only [Set.mem_iUnion]
rw [← hu]
simp only [Set.mem_iUnion]
constructor
· rintro ⟨i,hi⟩; exact ⟨e.symm i,hi⟩
· rintro ⟨i,hi⟩; exact ⟨e i, by simpa using hi⟩
theorem edgeDecomposition_singleEdges {V : Type} [Fintype V] (G : SimpleGraph V) :
EdgeDecomposition G (Nat.card G.edgeSet) := by
classical
let : Fintype G.edgeSet := Fintype.ofFinite _
rw [Nat.card_eq_fintype_card]
apply edgeDecomposition_of_indexed G (fun e : G.edgeSet => {e.1})
· intro e; exact Or.inr ⟨e.1,e.2,rfl⟩
· intro e d hed
exact Set.disjoint_singleton.mpr (fun h => hed (Subtype.ext h))
· ext e; simp
theorem edgeDecomposition_assemble {V I : Type} [Fintype I] (G : SimpleGraph V)
(W : I → Type) (H : ∀ i, SimpleGraph (W i))
(f : ∀ i, H i →g G) (hf : ∀ i, Function.Injective (f i))
(hdisj : Pairwise (fun i j =>
Disjoint (Sym2.map (f i) '' (H i).edgeSet) (Sym2.map (f j) '' (H j).edgeSet)))
(hcover : (⋃ i, Sym2.map (f i) '' (H i).edgeSet) = G.edgeSet)
(k : I → ℕ) (hparts : ∀ i, EdgeDecomposition (H i) (k i)) :
EdgeDecomposition G (∑ i, k i) := by
classical
choose parts hp hd hu using hparts
let J := Σ i, Fin (k i)
let P : J → Set (Sym2 V) := fun j => Sym2.map (f j.1) '' parts j.1 j.2
have hpart : ∀ j, CycleOrSingleEdge G (P j) := by
intro j; exact cycleOrSingleEdge_map (f j.1) (hf j.1) (hp j.1 j.2)
have hsub : ∀ i a, parts i a ⊆ (H i).edgeSet := by
intro i a; exact cycleOrSingleEdge_subset (hp i a)
have hdisjP : Pairwise (fun i j => Disjoint (P i) (P j)) := by
rintro ⟨i,a⟩ ⟨j,b⟩ hij
by_cases h : i = j
· subst j
have hab : a ≠ b := fun he => hij (by cases he; rfl)
apply Set.disjoint_left.mpr
rintro e ⟨x,hx,he⟩ ⟨y,hy,he'⟩
have hxy : x = y := Sym2.map.injective (hf i) (he.trans he'.symm)
subst y
exact Set.disjoint_left.mp (hd i hab) hx hy
· exact (hdisj h).mono (Set.image_mono (hsub i a)) (Set.image_mono (hsub j b))
have hcoverP : (⋃ j, P j) = G.edgeSet := by
rw [← hcover]
ext e
simp only [Set.mem_iUnion]
constructor
· rintro ⟨⟨i,a⟩,x,hx,he⟩
exact ⟨i,x,hsub i a hx,he⟩
· rintro ⟨i,x,hx,he⟩
rw [← hu i] at hx
obtain ⟨a,ha⟩ := Set.mem_iUnion.mp hx
exact ⟨⟨i,a⟩,x,ha,he⟩
have hc : Fintype.card J = ∑ i, k i := by simp [J, Fintype.card_sigma]
rw [← hc]
exact edgeDecomposition_of_indexed G P hpart hdisjP hcoverP
end
end ErdosGallai.Batch
namespace ErdosGallai.Batch
noncomputable section
open SimpleGraph Finset
attribute [local instance] Classical.propDecidable
def decompositionCost {V : Type} [Fintype V] (G : SimpleGraph V) : ℕ :=
Nat.find (show ∃ k, EdgeDecomposition G k from ⟨_,edgeDecomposition_singleEdges G⟩)
lemma decompositionCost_spec {V : Type} [Fintype V] (G : SimpleGraph V) :
EdgeDecomposition G (decompositionCost G) := Nat.find_spec _
lemma decompositionCost_le {V : Type} [Fintype V] {G : SimpleGraph V} {k : ℕ}
(h : EdgeDecomposition G k) : decompositionCost G ≤ k := Nat.find_min' _ h
lemma decompositionCost_singleEdges {V : Type} [Fintype V] (G : SimpleGraph V) :
decompositionCost G ≤ Nat.card G.edgeSet := decompositionCost_le (edgeDecomposition_singleEdges G)
theorem edgeDecomposition_adjoin {V I J : Type} [Fintype I] [Fintype J]
(G : SimpleGraph V) (parts : I → Set (Sym2 V))
(hp : ∀ i, CycleOrSingleEdge G (parts i))
(hd : Pairwise fun i j => Disjoint (parts i) (parts j))
(W : J → Type) (H : ∀ j, SimpleGraph (W j)) (f : ∀ j, H j →g G)
(hf : ∀ j, Function.Injective (f j))
(hHH : Pairwise fun i j => Disjoint (Sym2.map (f i) '' (H i).edgeSet)
(Sym2.map (f j) '' (H j).edgeSet))
(hHP : ∀ j i, Disjoint (Sym2.map (f j) '' (H j).edgeSet) (parts i))
(hu : (⋃ i, parts i) ∪ (⋃ j, Sym2.map (f j) '' (H j).edgeSet) = G.edgeSet)
(k : J → ℕ) (hD : ∀ j, EdgeDecomposition (H j) (k j)) :
EdgeDecomposition G (Fintype.card I + ∑ j, k j) := by
classical
choose P hP hPd hPc using hD
let R : (I ⊕ Σ j, Fin (k j)) → Set (Sym2 V) :=
Sum.elim parts (fun z => Sym2.map (f z.1) '' P z.1 z.2)
have hsub : ∀ j i, P j i ⊆ (H j).edgeSet := fun j i => cycleOrSingleEdge_subset (hP j i)
have hRp : ∀ z, CycleOrSingleEdge G (R z) := by
intro z
rcases z with z | ⟨j,i⟩
· exact hp z
· exact cycleOrSingleEdge_map (f j) (hf j) (hP j i)
have hRd : Pairwise fun z t => Disjoint (R z) (R t) := by
intro z t hzt
rcases z with z | ⟨j,i⟩ <;> rcases t with t | ⟨l,a⟩
· exact hd (fun h => hzt (congrArg Sum.inl h))
· exact ((hHP l z).mono_left (Set.image_mono (hsub l a))).symm
· exact (hHP j t).mono_left (Set.image_mono (hsub j i))
· by_cases hjl : j = l
· subst l
have hia : i ≠ a := fun h => hzt (by cases h; rfl)
apply Set.disjoint_left.mpr
rintro e ⟨x,hx,he⟩ ⟨y,hy,he'⟩
have hxy := Sym2.map.injective (hf j) (he.trans he'.symm)
subst y
exact Set.disjoint_left.mp (hPd j hia) hx hy
· exact (hHH hjl).mono (Set.image_mono (hsub j i)) (Set.image_mono (hsub l a))
have hRu : (⋃ z, R z) = G.edgeSet := by
rw [← hu]
ext e
simp only [Set.mem_iUnion, Set.mem_union]
constructor
· rintro ⟨z,hz⟩
rcases z with z | ⟨j,i⟩
· exact Or.inl ⟨z,hz⟩
· obtain ⟨x,hx,he⟩ := hz
exact Or.inr ⟨j,x,hsub j i hx,he⟩
· rintro (⟨i,hi⟩ | ⟨j,x,hx,he⟩)
· exact ⟨Sum.inl i,hi⟩
· rw [← hPc j] at hx
obtain ⟨i,hi⟩ := Set.mem_iUnion.mp hx
exact ⟨Sum.inr ⟨j,i⟩,x,hi,he⟩
simpa only [Fintype.card_sum,Fintype.card_sigma,Fintype.card_fin] using
edgeDecomposition_of_indexed G R hRp hRd hRu
lemma decompositionCost_adjoin {V I J : Type} [Fintype V] [Fintype I] [Fintype J]
(G : SimpleGraph V) (parts : I → Set (Sym2 V))
(hp : ∀ i, CycleOrSingleEdge G (parts i))
(hd : Pairwise fun i j => Disjoint (parts i) (parts j))
(W : J → Type) [∀ j, Fintype (W j)] (H : ∀ j, SimpleGraph (W j))
(f : ∀ j, H j →g G) (hf : ∀ j, Function.Injective (f j))
(hHH : Pairwise fun i j => Disjoint (Sym2.map (f i) '' (H i).edgeSet)
(Sym2.map (f j) '' (H j).edgeSet))
(hHP : ∀ j i, Disjoint (Sym2.map (f j) '' (H j).edgeSet) (parts i))
(hu : (⋃ i, parts i) ∪ (⋃ j, Sym2.map (f j) '' (H j).edgeSet) = G.edgeSet) :
decompositionCost G ≤ Fintype.card I + ∑ j, decompositionCost (H j) :=
decompositionCost_le (edgeDecomposition_adjoin G parts hp hd W H f hf hHH hHP hu _
(fun j => decompositionCost_spec (H j)))
end
end ErdosGallai.Batch
namespace ErdosGallai.Batch
noncomputable section
open SimpleGraph Finset
attribute [local instance] Classical.propDecidable
lemma edgeDecomposition_map {V W : Type} {G : SimpleGraph V} {H : SimpleGraph W}
(f : H →g G) (hf : Function.Injective f)
(hu : Sym2.map f '' H.edgeSet = G.edgeSet) {k : ℕ} (hk : EdgeDecomposition H k) :
EdgeDecomposition G k := by
have := edgeDecomposition_assemble (I := Unit) G (fun _ : Unit => W) (fun _ => H) (fun _ => f)
(fun _ => hf) (by intro i j hij; exact False.elim (hij (Subsingleton.elim _ _)))
(by rw [Set.iUnion_const]; exact hu) (fun _ => k) (fun _ => hk)
simpa using this
lemma decompositionCost_on {V : Type} [Fintype V] (G : SimpleGraph V)
(A : Finset V) (hA : ∀ ⦃x y⦄, G.Adj x y → x ∈ A ∧ y ∈ A) :
decompositionCost G ≤ decompositionCost (G.induce (A:Set V)) := by
classical
let f : G.induce (A:Set V) →g G := ⟨Subtype.val,fun h => h⟩
have hu : Sym2.map f '' (G.induce (A:Set V)).edgeSet = G.edgeSet := by
ext e
constructor
· rintro ⟨e,he,rfl⟩
induction e using Sym2.ind with | _ x y => exact he
· intro he
induction e using Sym2.ind with
| _ x y =>
exact ⟨s(⟨x,(hA he).1⟩,⟨y,(hA he).2⟩),he,rfl⟩
exact decompositionCost_le (edgeDecomposition_map f Subtype.val_injective hu (decompositionCost_spec _))
lemma edgeDecomposition_on {V : Type} (G : SimpleGraph V)
(A : Finset V) (hA : ∀ ⦃x y⦄, G.Adj x y → x ∈ A ∧ y ∈ A)
{k : ℕ} (hk : EdgeDecomposition (G.induce (A:Set V)) k) : EdgeDecomposition G k := by
classical
let f : G.induce (A:Set V) →g G := ⟨Subtype.val,fun h => h⟩
apply edgeDecomposition_map f Subtype.val_injective _ hk
ext e
constructor
· rintro ⟨e,he,rfl⟩
induction e using Sym2.ind with | _ x y => exact he
· intro he
induction e using Sym2.ind with
| _ x y => exact ⟨s(⟨x,(hA he).1⟩,⟨y,(hA he).2⟩),he,rfl⟩
end
end ErdosGallai.Batch
namespace ErdosGallai.Batch
noncomputable section
open Finset SimpleGraph
attribute [local instance] Classical.propDecidable
lemma endpointLoad_subtype_le {V I : Type} [Fintype I]
(x y : I → V) (s : I → Prop) (v : V) :
endpointLoad univ (fun i : {i // s i} => x i) (fun i => y i) v ≤ endpointLoad univ x y v := by
classical
simp only [endpointLoad]
apply Finset.card_le_card_of_injOn (fun i : {i // s i} => i.val)
· intro i hi; simpa using hi
· intro i _ j _ h; exact Subtype.ext h
theorem uniform_multi_batch_routing :
∃ D₀ : ℝ, 1 < D₀ ∧ ∀ D ≥ D₀,
∀ (V R I T : Type) [Fintype V] [Fintype R] [Fintype I],
∀ (G : SimpleGraph V) (P : R → SimpleGraph V) (U : R → Finset V),
(∀ r, P r ≤ G) → Pairwise (fun r s => Disjoint (P r).edgeSet (P s).edgeSet) →
Pairwise (fun r s => Disjoint (U r) (U s)) →
(∀ r, CutExpansionOn (P r) (U r) (D^(9/10:ℝ)/4)) →
(∀ r, D^(9/10:ℝ) ≤ ((U r).card:ℝ) ∧ ((U r).card:ℝ) ≤ D^(51/50:ℝ)) →
∀ (owner : I → R) (x y : I → V),
(∀ i, x i ∈ U (owner i) ∧ y i ∈ U (owner i) ∧ x i ≠ y i) →
∀ (team : I → T) (Z : I → Finset V),
(∀ v, (endpointLoad univ x y v:ℝ) ≤ D^(1/100:ℝ)) →
(∀ i, ((univ.filter (fun j => team j = team i)).card:ℝ) ≤ D^(3/10:ℝ)) →
(∀ i, ((Z i).card:ℝ) ≤ 2*D^(3/10:ℝ)) →
∃ q : ∀ i, G.Walk (x i) (y i),
(∀ i, (q i).IsPath ∧ (∀ v ∈ (q i).support, v ∈ U (owner i)) ∧
(q i).edgeSet ⊆ (P (owner i)).edgeSet ∧ Disjoint (pathInterior (q i)) (Z i)) ∧
Pairwise (fun i j => Disjoint (q i).edgeSet (q j).edgeSet) ∧
(∀ i j, i ≠ j → team i = team j → Disjoint (pathInterior (q i)) (pathInterior (q j))) := by
classical
obtain ⟨D₀,hD₀,hroute⟩ := uniform_batch_routing
refine ⟨D₀,hD₀,?_⟩
intro D hD V R I T _ _ _ G P U hPG hPP hUU he hr owner x y hxy team Z hl ht hZ
let J := fun r => {i // owner i = r}
have hex : ∀ r, ∃ q : ∀ i : J r, G.Walk (x i) (y i),
(∀ i, (q i).IsPath ∧ (∀ v ∈ (q i).support, v ∈ U r) ∧
(q i).edgeSet ⊆ (P r).edgeSet ∧ Disjoint (pathInterior (q i)) (Z i)) ∧
Pairwise (fun i j => Disjoint (q i).edgeSet (q j).edgeSet) ∧
(∀ i j : J r, i ≠ j → team i = team j → Disjoint (pathInterior (q i)) (pathInterior (q j))) := by
intro r
obtain ⟨q,hq,hd,hi⟩ := hroute D hD V G (P r) (hPG r) (U r) (he r) (hr r).1 (hr r).2
(J r) T (fun i => x i) (fun i => y i)
(fun i => by simpa only [← i.property] using (hxy i).1)
(fun i => by simpa only [← i.property] using (hxy i).2.1)
(fun i => (hxy i).2.2) (fun i => team i) (fun i => Z i)
(fun v => (show (endpointLoad univ (fun i : J r => x i) (fun i => y i) v:ℝ) ≤
endpointLoad univ x y v by exact_mod_cast endpointLoad_subtype_le x y (fun i => owner i = r) v).trans (hl v))
(fun i => le_trans (by
apply Nat.cast_le.mpr
apply Finset.card_le_card_of_injOn (fun i : J r => i.val)
· intro j hj; simpa using hj
· intro j _ l _ h; exact Subtype.ext h) (ht i)) (fun i => hZ i)
exact ⟨q,fun i => ⟨(hq i).1,(hq i).2.2⟩,hd,hi⟩
choose q hq hd hi using hex
let f : ∀ i, G.Walk (x i) (y i) := fun i => q (owner i) ⟨i,rfl⟩
have hf (i : I) (r : R) (h : owner i = r) : f i = q r ⟨i,h⟩ := by
subst r; rfl
refine ⟨f,fun i => hq _ _,?_,?_⟩
· intro i j hij
by_cases hh : owner i = owner j
· have h := hd (owner i) (show (⟨i,rfl⟩:J (owner i)) ≠ ⟨j,hh.symm⟩ from
fun h => hij (congrArg Subtype.val h))
rw [hf j (owner i) hh.symm]
exact h
· exact (hPP hh).mono (hq _ _).2.2.1 (hq _ _).2.2.1
· intro i j hij hteam
by_cases hh : owner i = owner j
· have h := hi (owner i) ⟨i,rfl⟩ ⟨j,hh.symm⟩
(fun h => hij (congrArg Subtype.val h)) hteam
rw [hf j (owner i) hh.symm]
exact h
· apply (hUU hh).mono
· intro v hv; exact (hq (owner i) ⟨i,rfl⟩).2.1 v (List.mem_toFinset.mp (Finset.mem_sdiff.mp hv).1)
· intro v hv; exact (hq (owner j) ⟨j,rfl⟩).2.1 v (List.mem_toFinset.mp (Finset.mem_sdiff.mp hv).1)
structure CycleOutline {V : Type} (G : SimpleGraph V) where
W : Type
finiteW : Fintype W
Q : SimpleGraph W
base : W
cycle : Q.Walk base base
isCycle : cycle.IsCycle
rep : Q.Dart → G.Dart
start : W → V
finish : W → V
project : V → W
ports : ∀ d ∈ cycle.darts, finish d.fst = (rep d).fst ∧ start d.snd = (rep d).snd
projects : ∀ z ∈ cycle.dropLast.support, project (start z) = z ∧ project (finish z) = z
outside : ∀ z, z ∉ cycle.dropLast.support → start z = finish z
attribute [instance] CycleOutline.finiteW
namespace CycleOutline
variable {V : Type} {G : SimpleGraph V} (c : CycleOutline G)
def edges : Set (Sym2 V) := {e | ∃ d ∈ c.cycle.darts, e = (c.rep d).edge}
def vertices : Finset V := c.cycle.darts.toFinset.biUnion fun d => {(c.rep d).fst,(c.rep d).snd}
abbrev Switch := {z : c.W // z ∈ c.cycle.dropLast.support ∧ c.start z ≠ c.finish z}
instance : Fintype c.Switch := inferInstanceAs (Fintype {_z : c.W // _})
lemma edges_subset : c.edges ⊆ G.edgeSet := by
rintro e ⟨d,hd,rfl⟩; exact (c.rep d).edge_mem
lemma fst_mem {d : c.Q.Dart} (hd : d ∈ c.cycle.darts) : d.fst ∈ c.cycle.dropLast.support := by
rw [c.cycle.support_dropLast c.isCycle.not_nil,← Walk.map_fst_darts]
exact List.mem_map.mpr ⟨d,hd,rfl⟩
lemma snd_mem {d : c.Q.Dart} (hd : d ∈ c.cycle.darts) : d.snd ∈ c.cycle.dropLast.support := by
rw [c.cycle.support_dropLast c.isCycle.not_nil]
apply c.cycle.tail_support_perm_dropLast_support.mem_iff.mp
rw [← Walk.map_snd_darts]
exact List.mem_map.mpr ⟨d,hd,rfl⟩
lemma outgoing (z : c.W) (hz : z ∈ c.cycle.dropLast.support) :
∃ d ∈ c.cycle.darts, d.fst = z := by
have h : z ∈ c.cycle.darts.map (fun d => d.fst) := by
rw [Walk.map_fst_darts,← c.cycle.support_dropLast c.isCycle.not_nil]; exact hz
exact List.mem_map.mp h
lemma incoming (z : c.W) (hz : z ∈ c.cycle.dropLast.support) :
∃ d ∈ c.cycle.darts, d.snd = z := by
have h : z ∈ c.cycle.darts.map (fun d => d.snd) := by
rw [Walk.map_snd_darts]
apply c.cycle.tail_support_perm_dropLast_support.mem_iff.mpr
rw [← c.cycle.support_dropLast c.isCycle.not_nil]; exact hz
exact List.mem_map.mp h
lemma endpoint_incident (z : c.Switch) (v : V) (hv : c.start z = v ∨ c.finish z = v) :
∃ w, G.Adj v w ∧ s(v,w) ∈ c.edges := by
rcases hv with rfl | rfl
· obtain ⟨d,hd,he⟩ := c.incoming z z.property.1
have hh := (c.ports d hd).2
rw [he] at hh
refine ⟨(c.rep d).fst,?_,?_⟩
· rw [hh]; exact (c.rep d).adj.symm
· refine ⟨d,hd,?_⟩
rw [hh]; exact Sym2.eq_swap
· obtain ⟨d,hd,he⟩ := c.outgoing z z.property.1
have hh := (c.ports d hd).1
rw [he] at hh
refine ⟨(c.rep d).snd,?_,?_⟩
· rw [hh]; exact (c.rep d).adj
· refine ⟨d,hd,?_⟩; rw [hh]; rfl
lemma endpoint_unique (z w : c.Switch) (v : V)
(hz : c.start z = v ∨ c.finish z = v) (hw : c.start w = v ∨ c.finish w = v) : z = w := by
apply Subtype.ext
have hf : ∀ (z : c.Switch), c.start z = v ∨ c.finish z = v → c.project v = z := by
intro z hz
rcases hz with h | h
· rw [← h]; exact (c.projects z z.property.1).1
· rw [← h]; exact (c.projects z z.property.1).2
exact (hf z hz).symm.trans (hf w hw)
lemma vertices_card_support : c.vertices.card ≤ 2 * c.cycle.dropLast.support.toFinset.card := by
have hfirst : c.vertices.card ≤ 2*c.cycle.darts.toFinset.card := by
calc
_ ≤ ∑ d ∈ c.cycle.darts.toFinset, ({(c.rep d).fst,(c.rep d).snd}:Finset V).card := Finset.card_biUnion_le
_ ≤ ∑ d ∈ c.cycle.darts.toFinset, 2 := Finset.sum_le_sum (fun d _ => Finset.card_le_two)
_ = _ := by simp [mul_comm]
have hd : c.cycle.darts.toFinset.card ≤ c.cycle.dropLast.support.toFinset.card := by
calc
_ ≤ c.cycle.darts.length := List.toFinset_card_le _
_ = c.cycle.dropLast.support.length := by
rw [Walk.length_darts,Walk.length_support,Walk.length_dropLast]
have := c.isCycle.three_le_length; omega
_ = c.cycle.dropLast.support.toFinset.card := (List.toFinset_card_of_nodup c.isCycle.isPath_dropLast.support_nodup).symm
omega
lemma vertices_card : c.vertices.card ≤ 2 * Fintype.card c.W :=
c.vertices_card_support.trans (Nat.mul_le_mul_left _ (Finset.card_le_univ _))
lemma mem_vertices (v : V) : v ∈ c.vertices ↔ ∃ d ∈ c.cycle.darts, v = (c.rep d).fst ∨ v = (c.rep d).snd := by
simp [vertices]
theorem complete [DecidableEq V]
(route : ∀ z : c.Switch, G.Walk (c.start z) (c.finish z))
(hs : ∀ z, (route z).IsPath)
(ha : ∀ z, Disjoint (pathInterior (route z)) c.vertices)
(hd : Pairwise fun z w => Disjoint (pathInterior (route z)) (pathInterior (route w))) :
∃ (v : V) (p : G.Walk v v), p.IsCycle ∧
p.edgeSet = c.edges ∪ ⋃ z, (route z).edgeSet := by
classical
let visits : ∀ z, G.Walk (c.start z) (c.finish z) := fun z =>
if h : z ∈ c.cycle.dropLast.support ∧ c.start z ≠ c.finish z then route ⟨z,h⟩
else (Walk.nil : G.Walk (c.start z) (c.start z)).copy rfl (by
by_cases hz : z ∈ c.cycle.dropLast.support
· exact not_not.mp (fun hn => h ⟨hz,hn⟩)
· exact c.outside z hz)
have hv (z : c.Switch) : visits z = route z := by simp only [visits,dite_eq_left z.property]
have hnil (z : c.W) (hz : ¬(z ∈ c.cycle.dropLast.support ∧ c.start z ≠ c.finish z)) :
(visits z).Nil := by simp only [visits,dite_eq_right hz,Walk.nil_copy,Walk.nil_nil]
have hpath : ∀ z, (visits z).IsPath := by
intro z
by_cases hz : z ∈ c.cycle.dropLast.support ∧ c.start z ≠ c.finish z
· simpa only [visits,dite_eq_left hz] using hs ⟨z,hz⟩
· simp [visits,dite_eq_right hz]
have hinter (z : c.W) : visitInterior c.start c.finish visits z = (pathInterior (visits z):Set V) := by
ext v; simp [visitInterior,pathInterior]
have h_avoid : ∀ z ∈ c.cycle.dropLast.support, Disjoint
(visitInterior c.start c.finish visits z) {v | ∃ d ∈ c.cycle.darts, v = (c.rep d).fst ∨ v = (c.rep d).snd} := by
intro z hz
rw [hinter]
have he : {v | ∃ d ∈ c.cycle.darts, v = (c.rep d).fst ∨ v = (c.rep d).snd} = (c.vertices:Set V) := by
ext v; exact (c.mem_vertices v).symm
rw [he,Finset.disjoint_coe]
by_cases hne : c.start z ≠ c.finish z
· rw [hv ⟨z,hz,hne⟩]; exact ha _
· have hn := hnil z (by tauto)
simp [Finset.disjoint_left,pathInterior,Walk.nil_iff_support_eq.mp hn]
have h_dis : Pairwise fun z w : {z // z ∈ c.cycle.dropLast.support} =>
Disjoint (visitInterior c.start c.finish visits z) (visitInterior c.start c.finish visits w) := by
intro z w hzw
rw [hinter,hinter,Finset.disjoint_coe]
by_cases hz : c.start z ≠ c.finish z
· by_cases hw : c.start w ≠ c.finish w
· rw [hv ⟨z,z.property,hz⟩,hv ⟨w,w.property,hw⟩]
exact hd (fun h => hzw (Subtype.ext (congrArg (fun t : c.Switch => (t:c.W)) h)))
· have hn := hnil w (by tauto); simp [Finset.disjoint_left,pathInterior,Walk.nil_iff_support_eq.mp hn] ; tauto
· have hn := hnil z (by tauto); simp [Finset.disjoint_left,pathInterior,Walk.nil_iff_support_eq.mp hn]
obtain ⟨v,p,hp,hedge⟩ := inflate_represented_cycle c.rep c.start c.finish c.cycle c.isCycle c.ports visits
(fun z _ => hpath z) (switch_supports_separated {z | z ∈ c.cycle.dropLast.support}
c.project c.start c.finish visits c.projects
(by
intro z hz
rw [cyclePortSet_eq_representative_vertices c.rep c.start c.finish c.cycle c.isCycle c.ports]
exact h_avoid z hz)
(fun z hz w hw hzw => h_dis (show (⟨z,hz⟩:{z // z ∈ c.cycle.dropLast.support}) ≠ ⟨w,hw⟩ from
fun h => hzw (congrArg Subtype.val h))))
refine ⟨v,p,hp,hedge.trans ?_⟩
congr 1
ext e
simp only [Set.mem_iUnion]
constructor
· rintro ⟨z,hz,he⟩
by_cases hne : c.start z ≠ c.finish z
· exact ⟨⟨z,hz,hne⟩,by rwa [hv ⟨z,hz,hne⟩] at he⟩
· have hn := hnil z (by tauto)
have hh := he
simp [Walk.edgeSet,Walk.edges_eq_nil.mpr hn] at hh
· rintro ⟨z,he⟩; exact ⟨z,z.property.1,by rwa [hv]⟩
end CycleOutline
end
end ErdosGallai.Batch
namespace ErdosGallai.Batch
noncomputable section
open Finset SimpleGraph
attribute [local instance] Classical.propDecidable
structure RoutingTemplate {V : Type} (G : SimpleGraph V) where
Arity : Type
finiteArity : Fintype Arity
x : Arity → V
y : Arity → V
ne : ∀ i, x i ≠ y i
edges : Set (Sym2 V)
subset : edges ⊆ G.edgeSet
vertices : Finset V
incident : ∀ i v, x i = v ∨ y i = v → ∃ w, s(v,w) ∈ edges
unique : ∀ i j v, (x i = v ∨ y i = v) → (x j = v ∨ y j = v) → i = j
complete : ∀ q : ∀ i, G.Walk (x i) (y i),
(∀ i, (q i).IsPath) →
(∀ i, Disjoint (pathInterior (q i)) vertices) →
Pairwise (fun i j => Disjoint (pathInterior (q i)) (pathInterior (q j))) →
CycleOrSingleEdge G (edges ∪ ⋃ i, (q i).edgeSet)
attribute [instance] RoutingTemplate.finiteArity
namespace RoutingTemplate
variable {V : Type} {G : SimpleGraph V}
def ofCycle (c : CycleOutline G) : RoutingTemplate G where
Arity := c.Switch
finiteArity := inferInstance
x := fun i => c.start i
y := fun i => c.finish i
ne := fun i => i.property.2
edges := c.edges
subset := c.edges_subset
vertices := c.vertices
incident := fun i v h => by obtain ⟨w,_,he⟩ := c.endpoint_incident i v h; exact ⟨w,he⟩
unique := c.endpoint_unique
complete := by
intro q hs ha hd
obtain ⟨v,p,hp,he⟩ := c.complete q hs ha hd
exact Or.inl ⟨v,p,hp,he.symm⟩
def ofSingle (e : Sym2 V) (he : e ∈ G.edgeSet) : RoutingTemplate G where
Arity := Empty
finiteArity := inferInstance
x := Empty.elim
y := Empty.elim
ne := fun i => i.elim
edges := {e}
subset := Set.singleton_subset_iff.mpr he
vertices := ∅
incident := fun i => i.elim
unique := fun i => i.elim
complete := by intro q _ _ _; exact Or.inr ⟨e,he,by simp⟩
def ofPath {x y : V} (p : G.Walk x y) (hp : p.IsPath) (hl : 2 ≤ p.length) : RoutingTemplate G where
Arity := Unit
finiteArity := inferInstance
x := fun _ => y
y := fun _ => x
ne := fun _ he => by
have hn : p.Nil := hp.nil_iff_eq.mpr he.symm
have := Walk.length_eq_zero_iff.mpr hn
omega
edges := p.edgeSet
subset := p.edges_subset_edgeSet
vertices := p.support.toFinset
incident := by
intro i v hv
have hn : ¬p.Nil := fun h => by have := Walk.length_eq_zero_iff.mpr h; omega
rcases hv with rfl | rfl
· obtain ⟨w,_,he⟩ := finish_has_incident_edge p hn; exact ⟨w,he⟩
· obtain ⟨w,_,he⟩ := start_has_incident_edge p hn; exact ⟨w,he⟩
unique := fun _ _ _ _ _ => Subsingleton.elim _ _
complete := by
intro q hs ha hd
obtain ⟨hc,he⟩ := close_trimmed_path p (q ()) hp (hs ()) hl (by
intro v hv hxa hxb hpv
exact Finset.disjoint_left.mp (ha ())
(by simp [pathInterior,hv,hxa,hxb]) (List.mem_toFinset.mpr hpv))
refine Or.inl ⟨x,p.append (q ()),hc,?_⟩
have hh : ∀ i : Unit, q i = q () := fun i => by cases i; rfl
simp_rw [hh,Set.iUnion_const]
exact he.symm
lemma ofCycle_arity_card (c : CycleOutline G) :
Fintype.card (ofCycle c).Arity ≤ Fintype.card c.W := Fintype.card_subtype_le _
lemma ofPath_vertices_card [Fintype V] {x y : V} (p : G.Walk x y) (hp : p.IsPath) (hl : 2 ≤ p.length) :
(ofPath p hp hl).vertices.card ≤ Fintype.card V := Finset.card_le_univ _
end RoutingTemplate
theorem uniform_resolve_templates :
∃ D₀ : ℝ, 1 < D₀ ∧ ∀ D ≥ D₀,
∀ (V R B : Type) [Fintype V] [Fintype R] [Fintype B],
∀ (G F : SimpleGraph V) (P : R → SimpleGraph V) (U : R → Finset V),
F ≤ G → (∀ r, P r ≤ G) →
Pairwise (fun r s => Disjoint (P r).edgeSet (P s).edgeSet) →
Pairwise (fun r s => Disjoint (U r) (U s)) →
(∀ r, Disjoint F.edgeSet (P r).edgeSet) →
(∀ r, CutExpansionOn (P r) (U r) (D^(9/10:ℝ)/4)) →
(∀ r, D^(9/10:ℝ) ≤ ((U r).card:ℝ) ∧ ((U r).card:ℝ) ≤ D^(51/50:ℝ)) →
∀ (b : B → RoutingTemplate G),
(∀ j, (b j).edges ⊆ F.edgeSet) →
Pairwise (fun j k => Disjoint (b j).edges (b k).edges) →
∀ owner : (j : B) → (b j).Arity → R,
(∀ j i, (b j).x i ∈ U (owner j i) ∧ (b j).y i ∈ U (owner j i)) →
(∀ j i, (F.degree ((b j).x i):ℝ) ≤ D^(1/100:ℝ) ∧
(F.degree ((b j).y i):ℝ) ≤ D^(1/100:ℝ)) →
(∀ j, (Fintype.card (b j).Arity:ℝ) ≤ D^(3/10:ℝ)) →
(∀ j, ((b j).vertices.card:ℝ) ≤ 2*D^(3/10:ℝ)) →
∃ (parts : B → Set (Sym2 V)) (used : Set (Sym2 V)),
(∀ j, CycleOrSingleEdge G (parts j)) ∧
Pairwise (fun j k => Disjoint (parts j) (parts k)) ∧
used ⊆ ⋃ r, (P r).edgeSet ∧ Disjoint F.edgeSet used ∧
(⋃ j, parts j) = (⋃ j, (b j).edges) ∪ used := by
classical
obtain ⟨D₀,hD₀,hr⟩ := uniform_multi_batch_routing
refine ⟨D₀,hD₀,?_⟩
intro D hD V R B _ _ _ G F P U hFG hPG hPP hUU hFP he hsize b hsub hdis owner hends hdeg hnum hvertices
let I := Σ j, (b j).Arity
let x : I → V := fun i => (b i.1).x i.2
let y : I → V := fun i => (b i.1).y i.2
have hl (v : V) : (endpointLoad univ x y v:ℝ) ≤ D^(1/100:ℝ) := by
have hload : endpointLoad univ x y v ≤ F.degree v := by
have hh := demand_load_le_degree F (fun j => (b j).edges) hdis
Sigma.fst x y (by
rintro ⟨j,i⟩ ⟨k,l⟩ v h h₁ h₂
dsimp only at h; subst k
congr 1; exact (b j).unique i l v h₁ h₂) (by
rintro ⟨j,i⟩ v h
obtain ⟨w,hw⟩ := (b j).incident i v h
exact ⟨w,hsub j hw,hw⟩) v
simpa [demandLoad,endpointLoad] using hh
by_cases hz : endpointLoad univ x y v = 0
· rw [hz,Nat.cast_zero]; exact Real.rpow_nonneg (by linarith) _
· have hp : 0 < (univ.filter fun i => x i = v ∨ y i = v).card := by
change 0 < endpointLoad univ x y v; omega
obtain ⟨⟨j,i⟩,hi⟩ := Finset.card_pos.mp hp
have hv : (b j).x i = v ∨ (b j).y i = v := (Finset.mem_filter.mp hi).2
have hh : (F.degree v:ℝ) ≤ D^(1/100:ℝ) := by
rcases hv with rfl | rfl
· exact (hdeg j i).1
· exact (hdeg j i).2
exact (Nat.cast_le.mpr hload).trans hh
have hteam (i : I) : ((univ.filter fun j : I => j.1 = i.1).card:ℝ) ≤ D^(3/10:ℝ) := by
have hc : (univ.filter fun j : I => j.1 = i.1).card = Fintype.card (b i.1).Arity := by
rw [Finset.card_eq_sum_ones,Finset.sum_filter,Fintype.sum_sigma]
calc
_ = ∑ j : B, if j = i.1 then Fintype.card (b j).Arity else 0 := by
apply Finset.sum_congr rfl; intro j _
by_cases hh : j = i.1 <;> simp [hh]
_ = _ := by simp
rw [hc]; exact hnum i.1
obtain ⟨q,hq,hqd,hqi⟩ := hr D hD V R I B G P U hPG hPP hUU he hsize
(fun i => owner i.1 i.2) x y (fun i => ⟨(hends i.1 i.2).1,(hends i.1 i.2).2,(b i.1).ne i.2⟩)
Sigma.fst (fun i => (b i.1).vertices) hl hteam (fun i => hvertices i.1)
let used := ⋃ i, (q i).edgeSet
let parts := fun j => (b j).edges ∪ ⋃ i, (q ⟨j,i⟩).edgeSet
have hu : used ⊆ ⋃ r, (P r).edgeSet := by
apply Set.iUnion_subset; intro i
exact Set.subset_iUnion_of_subset (owner i.1 i.2) (hq i).2.2.1
have hFu : Disjoint F.edgeSet used := by
refine Set.disjoint_iUnion_right.mpr (fun i => ?_)
exact (hFP _).mono_right (hq i).2.2.1
have hbu : ∀ j, Disjoint (b j).edges used := fun j => hFu.mono_left (hsub j)
refine ⟨parts,used,?_,?_,hu,hFu,?_⟩
· intro j
exact (b j).complete (fun i => q ⟨j,i⟩) (fun i => (hq _).1) (fun i => (hq _).2.2.2)
(fun i l hil => hqi _ _ (fun h => hil (eq_of_heq (Sigma.mk.inj_iff.mp h).2)) rfl)
· intro j k hjk
apply Set.disjoint_union_left.mpr; constructor
· apply Set.disjoint_union_right.mpr; constructor
· exact hdis hjk
· exact (hbu j).mono_right (Set.iUnion_subset (fun i => Set.subset_iUnion (fun z : I => (q z).edgeSet) ⟨k,i⟩))
· apply Set.disjoint_union_right.mpr; constructor
· exact ((hbu k).mono_right (Set.iUnion_subset (fun i => Set.subset_iUnion (fun z : I => (q z).edgeSet) ⟨j,i⟩))).symm
· apply Set.disjoint_iUnion_left.mpr; intro i
apply Set.disjoint_iUnion_right.mpr; intro l
exact hqd (fun h => hjk (congrArg Sigma.fst h))
· ext e
simp only [parts,used,Set.mem_iUnion,Set.mem_union]
constructor
· rintro ⟨j,he|⟨i,hi⟩⟩
· exact Or.inl ⟨j,he⟩
· exact Or.inr ⟨⟨j,i⟩,hi⟩
· rintro (⟨j,he⟩|⟨⟨j,i⟩,he⟩)
· exact ⟨j,Or.inl he⟩
· exact ⟨j,Or.inr ⟨i,he⟩⟩
end
end ErdosGallai.Batch
end
end
end
end OAI