openAI-math-dataset / lean /OAI /Probability /MatroidProphet /GroupConditioning.lean
roseking's picture
Add lean source and binary files (part 125)
dd14c26 verified
Raw History Blame Contribute Delete
19.4 kB
import OAI.Probability.MatroidProphet.Groups
import OAI.Probability.MatroidProphet.Residual.Statistics
import OAI.Probability.MatroidProphet.ProductSplit
namespace OAI
namespace MatroidProphet.MainAlgorithm
open Finset
variable {n : ℕ}
attribute [local instance] Classical.propDecidable
noncomputable def trueGroup (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) : Finset (Fin n) :=
univ.filter fun e => candidate M d s e (s e) ∧ s e = some i
@[simp] lemma mem_trueGroup (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (e : Fin n) :
e ∈ trueGroup M d s i ↔ candidate M d s e (s e) ∧ s e = some i := by
simp [trueGroup]
lemma trueGroup_disjoint (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) : Pairwise (fun i j => Disjoint (trueGroup M d s i) (trueGroup M d s j)) := by
intro i j hij
apply disjoint_left.mpr
intro e hei hej
exact hij (Option.some.inj (((mem_trueGroup M d s i e).mp hei).2.symm.trans
((mem_trueGroup M d s j e).mp hej).2))
lemma trueGroup_disjoint_H (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) : Disjoint (trueGroup M d s i) d.H := by
apply disjoint_left.mpr
intro e he hh
exact ((mem_trueGroup M d s i e).mp he).1.2.1 hh
lemma mem_listed_iff (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) :
i ∈ listed M d s ↔ ∃ e ∈ d.D, e ∈ trueGroup M d s i := by
simp only [listed, mem_biUnion, mem_trueGroup]
constructor
· rintro ⟨e, he, hi⟩
by_cases hc : candidate M d s e (s e)
· simp only [ite_eq_left hc, Option.mem_toFinset] at hi
exact ⟨e, he, hc, hi⟩
· simp only [ite_eq_right hc, Finset.notMem_empty] at hi
· rintro ⟨e, he, hc, hi⟩
exact ⟨e, he, by rw [ite_eq_left hc]; simp [hi]⟩
def withMasks (d : MainMasks n) (A B C : Finset (Fin n)) : MainMasks n :=
{ d with D := A, C := B, T := C }
@[simp] lemma candidate_withMasks (M : Matroid (Fin n)) (d : MainMasks n)
(A B C : Finset (Fin n)) (s : Fin n → Option ℤ) (e : Fin n) (v : Option ℤ) :
candidate M (withMasks d A B C) s e v ↔ candidate M d s e v := Iff.rfl
@[simp] lemma trueGroup_withMasks (M : Matroid (Fin n)) (d : MainMasks n)
(A B C : Finset (Fin n)) (s : Fin n → Option ℤ) (i : ℤ) :
trueGroup M (withMasks d A B C) s i = trueGroup M d s i := rfl
lemma groups_withMasks_guards (M : Matroid (Fin n)) (d : MainMasks n)
(A B C B' C' : Finset (Fin n)) (s : Fin n → Option ℤ) :
groups M (withMasks d A B C) s = groups M (withMasks d A B' C') s := rfl
def focalMasks (d : MainMasks n) (U A B C : Finset (Fin n)) : MainMasks n :=
{ d with D := (d.D \ U) ∪ A, C := (d.C \ U) ∪ B, T := (d.T \ U) ∪ C }
@[simp] lemma candidate_focalMasks (M : Matroid (Fin n)) (d : MainMasks n)
(U A B C : Finset (Fin n)) (s : Fin n → Option ℤ) (e : Fin n) (v : Option ℤ) :
candidate M (focalMasks d U A B C) s e v ↔ candidate M d s e v := Iff.rfl
@[simp] lemma trueGroup_focalMasks (M : Matroid (Fin n)) (d : MainMasks n)
(U A B C : Finset (Fin n)) (s : Fin n → Option ℤ) (i : ℤ) :
trueGroup M (focalMasks d U A B C) s i = trueGroup M d s i := rfl
lemma listed_focalMasks (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) :
listed M (focalMasks d (trueGroup M d s i) A B C) s =
(listed M d s \ {i}) ∪ (if A.Nonempty then {i} else ∅) := by
ext j
rw [mem_listed_iff]
simp only [focalMasks, mem_union, mem_sdiff,
mem_singleton, mem_listed_iff]
by_cases hne : A.Nonempty
· simp only [ite_eq_left hne, mem_singleton]
constructor
· rintro ⟨e, he | he, hej⟩
· refine Or.inl ⟨⟨e, he.1, hej⟩, ?_⟩
intro hji
exact he.2 (hji ▸ hej)
· exact Or.inr (Option.some.inj
(((mem_trueGroup M d s j e).mp hej).2.symm.trans
((mem_trueGroup M d s i e).mp (hA he)).2))
· rintro (⟨⟨e, heD, hej⟩, hji⟩ | rfl)
· refine ⟨e, Or.inl ⟨heD, ?_⟩, hej⟩
intro hei
exact hji (Option.some.inj
(((mem_trueGroup M d s j e).mp hej).2.symm.trans
((mem_trueGroup M d s i e).mp hei).2))
· obtain ⟨e, he⟩ := hne
exact ⟨e, Or.inr he, hA he⟩
· simp only [ite_eq_right hne, Finset.notMem_empty, or_false]
constructor
· rintro ⟨e, he | he, hej⟩
· refine ⟨⟨e, he.1, hej⟩, ?_⟩
intro hji
exact he.2 (hji ▸ hej)
· exact False.elim (hne ⟨e, he⟩)
· rintro ⟨⟨e, heD, hej⟩, hji⟩
refine ⟨e, Or.inl ⟨heD, ?_⟩, hej⟩
intro hei
exact hji (Option.some.inj
(((mem_trueGroup M d s j e).mp hej).2.symm.trans
((mem_trueGroup M d s i e).mp hei).2))
noncomputable def focalReference (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) : MainMasks n :=
focalMasks d (trueGroup M d s i) (trueGroup M d s i) ∅ ∅
lemma groups_focalMasks (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hne : A.Nonempty) :
groups M (focalMasks d (trueGroup M d s i) A B C) s =
groups M (focalReference M d s i) s := by
have hU : (trueGroup M d s i).Nonempty := hne.mono hA
unfold groups focalReference
rw [listed_focalMasks M d s i A B C hA,
listed_focalMasks M d s i _ ∅ ∅ Subset.rfl, ite_eq_left hne, ite_eq_left hU]
lemma focal_mem_reference_groups (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (hU : (trueGroup M d s i).Nonempty) :
i ∈ groups M (focalReference M d s i) s := by
rw [mem_groups]
unfold focalReference
rw [listed_focalMasks M d s i _ ∅ ∅ Subset.rfl, ite_eq_left hU]
exact mem_union_right _ (mem_singleton_self i)
lemma groupMask_at_key (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (mask : Finset (Fin n)) (h : ℕ) (i : ℤ)
(hi : (groups M d s)[h]? = some i) :
groupMask M d s mask h = ((mask ∩ trueGroup M d s i : Finset (Fin n)) : Set (Fin n)) := by
ext e
simp only [groupMask, Set.mem_ofPred_eq, Finset.mem_coe, mem_inter, mem_trueGroup, hi]
lemma replaceMask_inter_self (X U A : Finset (Fin n)) (hA : A ⊆ U) :
((X \ U) ∪ A) ∩ U = A := by
ext e
simp only [mem_inter, mem_union, mem_sdiff]
constructor
· rintro ⟨he | he, heU⟩
· exact False.elim (he.2 heU)
· exact he
· intro he
exact ⟨Or.inr he, hA he⟩
lemma replaceMask_inter_other (X U A V : Finset (Fin n))
(hA : A ⊆ U) (hUV : Disjoint U V) :
((X \ U) ∪ A) ∩ V = X ∩ V := by
ext e
simp only [mem_inter, mem_union, mem_sdiff]
constructor
· rintro ⟨he | he, heV⟩
· exact ⟨he.1, heV⟩
· exact False.elim (disjoint_left.mp hUV (hA he) heV)
· rintro ⟨heX, heV⟩
exact ⟨Or.inl ⟨heX, fun heU => disjoint_left.mp hUV heU heV⟩, heV⟩
noncomputable def focalIndex (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) : ℕ :=
(groups M (focalReference M d s i) s).idxOf i
lemma focal_group_key (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hne : A.Nonempty) :
(groups M (focalMasks d (trueGroup M d s i) A B C) s)[focalIndex M d s i]? = some i := by
rw [groups_focalMasks M d s i A B C hA hne]
exact groups_get?_idxOf M _ s i (focal_mem_reference_groups M d s i (hne.mono hA))
lemma focal_group_mask (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C X Y : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hne : A.Nonempty)
(hY : Y ⊆ trueGroup M d s i) :
groupMask M (focalMasks d (trueGroup M d s i) A B C) s
((X \ trueGroup M d s i) ∪ Y) (focalIndex M d s i) = (Y : Set (Fin n)) := by
rw [groupMask_at_key M _ s _ _ i (focal_group_key M d s i A B C hA hne),
trueGroup_focalMasks, replaceMask_inter_self X _ Y hY]
lemma lower_group_mask (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C X Y Z : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hne : A.Nonempty)
(hY : Y ⊆ trueGroup M d s i) (hZ : Z ⊆ trueGroup M d s i)
(j : ℕ) (hj : j < focalIndex M d s i) :
groupMask M (focalMasks d (trueGroup M d s i) A B C) s
((X \ trueGroup M d s i) ∪ Y) j =
groupMask M (focalReference M d s i) s
((X \ trueGroup M d s i) ∪ Z) j := by
have hi := groups_get?_idxOf M (focalReference M d s i) s i
(focal_mem_reference_groups M d s i (hne.mono hA))
obtain ⟨k, hk, hki⟩ := groups_earlier_key M (focalReference M d s i) s hi hj
have hk' : (groups M (focalMasks d (trueGroup M d s i) A B C) s)[j]? = some k := by
rwa [groups_focalMasks M d s i A B C hA hne]
have hdisj := trueGroup_disjoint M d s (ne_of_gt hki)
rw [groupMask_at_key M _ s _ j k hk', groupMask_at_key M _ s _ j k hk]
simp only [focalReference, trueGroup_focalMasks]
rw [replaceMask_inter_other X _ Y _ hY hdisj,
replaceMask_inter_other X _ Z _ hZ hdisj]
end MatroidProphet.MainAlgorithm
namespace MatroidProphet
open Set
variable {α : Type*} [Fintype α]
lemma guardedPath_congr_prefix (M : Matroid α) (hE : M.E = univ)
(κ : ℕ) (D C D' C' : ℕ → Set α) (h : ℕ)
(hD : ∀ j < h, D j = D' j) (hC : ∀ j < h, C j = C' j) (k : ℤ) :
guardedPath M hE κ D C h k = guardedPath M hE κ D' C' h k := by
induction h generalizing k with
| zero => rfl
| succ h ih =>
simp only [guardedPath, hD h (Nat.lt_succ_self h), hC h (Nat.lt_succ_self h),
ih (fun j hj => hD j (Nat.lt_succ_of_lt hj)) (fun j hj => hC j (Nat.lt_succ_of_lt hj))]
lemma nominalPath_congr_prefix (M : Matroid α) (hE : M.E = univ)
(κ : ℕ) (D C D' C' : ℕ → Set α) (h : ℕ)
(hD : ∀ j ≤ h, D j = D' j) (hC : ∀ j < h, C j = C' j) (k : ℤ) :
nominalPath M hE κ D C h k = nominalPath M hE κ D' C' h k := by
rw [nominalPath, nominalPath, hD h le_rfl,
guardedPath_congr_prefix M hE κ D C D' C' h (fun j hj => hD j hj.le) hC k]
lemma lowerCompetition_congr_prefix (M : Matroid α) (hE : M.E = univ)
(κ : ℕ) (D C T D' C' T' : ℕ → Set α) (h : ℕ)
(hD : ∀ j < h, D j = D' j) (hC : ∀ j < h, C j = C' j)
(hT : ∀ j < h, T j = T' j) (k : ℤ) :
lowerCompetition M hE κ D C T k h = lowerCompetition M hE κ D' C' T' k h := by
induction h with
| zero => rfl
| succ h ih =>
rw [lowerCompetition, lowerCompetition, hT h (Nat.lt_succ_self h),
ih (fun j hj => hD j (Nat.lt_succ_of_lt hj)) (fun j hj => hC j (Nat.lt_succ_of_lt hj))
(fun j hj => hT j (Nat.lt_succ_of_lt hj)),
nominalPath_congr_prefix M hE κ D C D' C' h
(fun j hj => hD j (Nat.lt_succ_of_le hj)) (fun j hj => hC j (Nat.lt_succ_of_lt hj)),
nominalPath_congr_prefix M hE κ D C D' C' h
(fun j hj => hD j (Nat.lt_succ_of_le hj)) (fun j hj => hC j (Nat.lt_succ_of_lt hj))]
namespace MainAlgorithm
open Finset
variable {n : ℕ}
attribute [local instance] Classical.propDecidable
lemma focal_prefix_masks (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hB : B ⊆ trueGroup M d s i)
(hC : C ⊆ trueGroup M d s i) (hne : A.Nonempty)
(j : ℕ) (hj : j < focalIndex M d s i) :
let f := focalMasks d (trueGroup M d s i) A B C
let r := focalReference M d s i
groupMask M f s f.D j = groupMask M r s r.D j ∧
groupMask M f s f.C j = groupMask M r s r.C j ∧
groupMask M f s f.T j = groupMask M r s r.T j := by
exact ⟨lower_group_mask M d s i A B C d.D A _ hA hne hA Finset.Subset.rfl j hj,
lower_group_mask M d s i A B C d.C B ∅ hA hne hB (empty_subset _) j hj,
lower_group_mask M d s i A B C d.T C ∅ hA hne hC (empty_subset _) j hj⟩
lemma focal_incoming_path (M : Matroid (Fin n)) (hE : M.E = Set.univ) (κ : ℕ)
(d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hB : B ⊆ trueGroup M d s i)
(hC : C ⊆ trueGroup M d s i) (hne : A.Nonempty) (k : ℤ) :
let f := focalMasks d (trueGroup M d s i) A B C
let r := focalReference M d s i
guardedPath M hE κ (groupMask M f s f.D) (groupMask M f s f.C) (focalIndex M d s i) k =
guardedPath M hE κ (groupMask M r s r.D) (groupMask M r s r.C) (focalIndex M d s i) k := by
apply guardedPath_congr_prefix
· exact fun j hj => (focal_prefix_masks M d s i A B C hA hB hC hne j hj).1
· exact fun j hj => (focal_prefix_masks M d s i A B C hA hB hC hne j hj).2.1
lemma focal_lowerCompetition (M : Matroid (Fin n)) (hE : M.E = Set.univ) (κ : ℕ)
(d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hB : B ⊆ trueGroup M d s i)
(hC : C ⊆ trueGroup M d s i) (hne : A.Nonempty) (k : ℤ) :
let f := focalMasks d (trueGroup M d s i) A B C
let r := focalReference M d s i
lowerCompetition M hE κ (groupMask M f s f.D) (groupMask M f s f.C)
(groupMask M f s f.T) k (focalIndex M d s i) =
lowerCompetition M hE κ (groupMask M r s r.D) (groupMask M r s r.C)
(groupMask M r s r.T) k (focalIndex M d s i) := by
apply lowerCompetition_congr_prefix
· exact fun j hj => (focal_prefix_masks M d s i A B C hA hB hC hne j hj).1
· exact fun j hj => (focal_prefix_masks M d s i A B C hA hB hC hne j hj).2.1
· exact fun j hj => (focal_prefix_masks M d s i A B C hA hB hC hne j hj).2.2
lemma focal_nominal_path (M : Matroid (Fin n)) (hE : M.E = Set.univ) (κ : ℕ)
(d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hB : B ⊆ trueGroup M d s i)
(hC : C ⊆ trueGroup M d s i) (hne : A.Nonempty) (k : ℤ) :
let f := focalMasks d (trueGroup M d s i) A B C
let r := focalReference M d s i
nominalPath M hE κ (groupMask M f s f.D) (groupMask M f s f.C) (focalIndex M d s i) k =
densityEnabled M hE κ (A : Set (Fin n)) (activation (focalIndex M d s i)) k
(guardedPath M hE κ (groupMask M r s r.D) (groupMask M r s r.C) (focalIndex M d s i) k) := by
dsimp only
rw [nominalPath, focal_incoming_path M hE κ d s i A B C hA hB hC hne k]
congr 1
exact focal_group_mask M d s i A B C d.D A hA hne hA
lemma focal_observed_inter (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) (hB : B ⊆ trueGroup M d s i) :
let f := focalMasks d (trueGroup M d s i) A B C
(f.H ∪ f.D ∪ f.C) ∩ trueGroup M d s i = A ∪ B := by
dsimp only [focalMasks]
rw [Finset.union_inter_distrib_right, Finset.union_inter_distrib_right,
disjoint_iff_inter_eq_empty.mp (trueGroup_disjoint_H M d s i).symm,
replaceMask_inter_self _ _ _ hA, replaceMask_inter_self _ _ _ hB, Finset.empty_union]
lemma focal_listed_iff_nonempty (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(hA : A ⊆ trueGroup M d s i) :
i ∈ groups M (focalMasks d (trueGroup M d s i) A B C) s ↔ A.Nonempty := by
rw [mem_groups, listed_focalMasks M d s i A B C hA]
by_cases hne : A.Nonempty <;> simp [hne]
noncomputable def listedSafeStatistic (M : Matroid (Fin n)) (hE : M.E = Set.univ)
(κ : ℕ) (d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ)
(Y : Set (Fin n)) (ε : Fin 2) : ℕ :=
if i ∈ groups M d s then
safeLayerStatistic M hE κ (groupMask M d s d.D) (groupMask M d s d.C)
(groupMask M d s d.T) ((groups M d s).idxOf i) (trueGroup M d s i : Set (Fin n))
((d.D : Set (Fin n)) ∩ Y) ε
else 0
noncomputable def listedRankStatistic (M : Matroid (Fin n)) (hE : M.E = Set.univ)
(κ : ℕ) (d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ) (ε : Fin 2) : ℕ :=
if i ∈ groups M d s then
nominalRankStatistic M hE κ (groupMask M d s d.D) (groupMask M d s d.C)
(groupMask M d s d.T) ((groups M d s).idxOf i) (trueGroup M d s i : Set (Fin n))
((d.H ∪ d.D ∪ d.C : Finset (Fin n)) : Set (Fin n)) ε
else 0
lemma listedSafeStatistic_focal_empty (M : Matroid (Fin n)) (hE : M.E = Set.univ)
(κ : ℕ) (d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ)
(B C : Finset (Fin n)) (Y : Set (Fin n)) (ε : Fin 2) :
listedSafeStatistic M hE κ (focalMasks d (trueGroup M d s i) ∅ B C) s i Y ε = 0 := by
rw [listedSafeStatistic, ite_eq_right]
simp only [focal_listed_iff_nonempty M d s i ∅ B C (Finset.empty_subset _),
Finset.not_nonempty_empty, not_false_eq_true]
lemma listedRankStatistic_focal_empty (M : Matroid (Fin n)) (hE : M.E = Set.univ)
(κ : ℕ) (d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ)
(B C : Finset (Fin n)) (ε : Fin 2) :
listedRankStatistic M hE κ (focalMasks d (trueGroup M d s i) ∅ B C) s i ε = 0 := by
rw [listedRankStatistic, ite_eq_right]
simp only [focal_listed_iff_nonempty M d s i ∅ B C (Finset.empty_subset _),
Finset.not_nonempty_empty, not_false_eq_true]
lemma listedSafeStatistic_focal_nonempty (M : Matroid (Fin n)) (hE : M.E = Set.univ)
(κ : ℕ) (d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ)
(A B C : Finset (Fin n)) (Y : Set (Fin n)) (ε : Fin 2)
(hA : A ⊆ trueGroup M d s i) (hne : A.Nonempty) :
let f := focalMasks d (trueGroup M d s i) A B C
listedSafeStatistic M hE κ f s i Y ε =
safeLayerStatistic M hE κ (groupMask M f s f.D) (groupMask M f s f.C)
(groupMask M f s f.T) (focalIndex M d s i) (trueGroup M d s i : Set (Fin n))
((f.D : Set (Fin n)) ∩ Y) ε := by
dsimp only
rw [listedSafeStatistic, ite_eq_left ((focal_listed_iff_nonempty M d s i A B C hA).mpr hne),
groups_focalMasks M d s i A B C hA hne, trueGroup_focalMasks]
rfl
lemma listedRankStatistic_focal_nonempty (M : Matroid (Fin n)) (hE : M.E = Set.univ)
(κ : ℕ) (d : MainMasks n) (s : Fin n → Option ℤ) (i : ℤ)
(A B C : Finset (Fin n)) (ε : Fin 2)
(hA : A ⊆ trueGroup M d s i) (hne : A.Nonempty) :
let f := focalMasks d (trueGroup M d s i) A B C
listedRankStatistic M hE κ f s i ε =
nominalRankStatistic M hE κ (groupMask M f s f.D) (groupMask M f s f.C)
(groupMask M f s f.T) (focalIndex M d s i) (trueGroup M d s i : Set (Fin n))
((f.H ∪ f.D ∪ f.C : Finset (Fin n)) : Set (Fin n)) ε := by
dsimp only
rw [listedRankStatistic, ite_eq_left ((focal_listed_iff_nonempty M d s i A B C hA).mpr hne),
groups_focalMasks M d s i A B C hA hne, trueGroup_focalMasks]
rfl
lemma focal_density_inter (M : Matroid (Fin n)) (d : MainMasks n)
(s : Fin n → Option ℤ) (i : ℤ) (A B C : Finset (Fin n))
(Y : Set (Fin n)) (hY : Y ⊆ (trueGroup M d s i : Set (Fin n))) :
((focalMasks d (trueGroup M d s i) A B C).D : Set (Fin n)) ∩ Y =
(A : Set (Fin n)) ∩ Y := by
ext e
simp only [Set.mem_inter_iff, Finset.mem_coe, focalMasks, Finset.mem_union,
Finset.mem_sdiff]
constructor
· rintro ⟨he | he, heY⟩
· exact False.elim (he.2 (hY heY))
· exact ⟨he, heY⟩
· rintro ⟨heA, heY⟩
exact ⟨Or.inr heA, heY⟩
end MainAlgorithm
end MatroidProphet
end OAI