HAL Id: hal-00530145
https://hal.archives-ouvertes.fr/hal-00530145
Preprint submitted on 27 Oct 2010
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Asymptotic normality of the Parzen-Rosenblatt density estimator for strongly mixing random fields
Mohamed El Machkouri
To cite this version:
Mohamed El Machkouri. Asymptotic normality of the Parzen-Rosenblatt density estimator for
strongly mixing random fields. 2010. �hal-00530145�
❆s②♠♣t♦t✐❝ ♥♦r♠❛❧✐t② ♦❢ t❤❡ P❛r③❡♥✲❘♦s❡♥❜❧❛tt
❞❡♥s✐t② ❡st✐♠❛t♦r ❢♦r str♦♥❣❧② ♠✐①✐♥❣ r❛♥❞♦♠ ✜❡❧❞s
▼♦❤❛♠❡❞ ❊▲ ▼❆❈❍❑❖❯❘■✱
▲❛❜♦r❛t♦✐r❡ ❞❡ ▼❛t❤é♠❛t✐q✉❡s ❘❛♣❤❛ë❧ ❙❛❧❡♠
❯▼❘ ❈◆❘❙ ✻✵✽✺✱ ❯♥✐✈❡rs✐té ❞❡ ❘♦✉❡♥
♠♦❤❛♠❡❞✳❡❧♠❛❝❤❦♦✉r✐❅✉♥✐✈✲r♦✉❡♥✳❢r
❖❝t♦❜❡r ✻✱ ✷✵✶✵
❆❜str❛❝t
❲❡ ♣r♦✈❡ t❤❡ ❛s②♠♣t♦t✐❝ ♥♦r♠❛❧✐t② ♦❢ t❤❡ ❦❡r♥❡❧ ❞❡♥s✐t② ❡st✐♠❛t♦r ✭✐♥tr♦❞✉❝❡❞
❜② ❘♦s❡♥❜❧❛tt ✭✶✾✺✻✮ ❛♥❞ P❛r③❡♥ ✭✶✾✻✷✮✮ ✐♥ t❤❡ ❝♦♥t❡①t ♦❢ st❛t✐♦♥❛r② str♦♥❣❧②
♠✐①✐♥❣ r❛♥❞♦♠ ✜❡❧❞s✳ ❖✉r ❛♣♣r♦❛❝❤ ✐s ❜❛s❡❞ ♦♥ t❤❡ ▲✐♥❞❡❜❡r❣✬s ♠❡t❤♦❞ r❛t❤❡r t❤❛♥ ♦♥ ❇❡r♥st❡✐♥✬s s♠❛❧❧✲❜❧♦❝❦✲❧❛r❣❡✲❜❧♦❝❦ t❡❝❤♥✐q✉❡ ❛♥❞ ❝♦✉♣❧✐♥❣ ❛r❣✉♠❡♥ts
✇✐❞❡❧② ✉s❡❞ ✐♥ ♣r❡✈✐♦✉s ✇♦r❦s ♦♥ ♥♦♥♣❛r❛♠❡tr✐❝ ❡st✐♠❛t✐♦♥ ❢♦r s♣❛t✐❛❧ ♣r♦❝❡ss❡s✳
❖✉r ♠❡t❤♦❞ ❛❧❧♦✇s ✉s t♦ ❝♦♥s✐❞❡r ♦♥❧② ♠✐♥✐♠❛❧ ❝♦♥❞✐t✐♦♥s ♦♥ t❤❡ ❜❛♥❞✇✐❞t❤ ♣❛✲
r❛♠❡t❡r ❛♥❞ ♣r♦✈✐❞❡s ❛ s✐♠♣❧❡ ❝r✐t❡r✐♦♥ ♦♥ t❤❡ str♦♥❣ ♠✐①✐♥❣ ❝♦❡✣❝✐❡♥ts ✇❤✐❝❤
❞♦ ♥♦t ❞❡♣❡♥❞ ♦♥ t❤❡ ❜❛♥❞✇✐t❤✳
❆▼❙ ❙✉❜❥❡❝t ❈❧❛ss✐✜❝❛t✐♦♥s ✭✷✵✵✵✮✿ ✻✷●✵✺✱ ✻✷●✵✼✱ ✻✵●✻✵✳
❑❡② ✇♦r❞s ❛♥❞ ♣❤r❛s❡s✿ ❈❡♥tr❛❧ ❧✐♠✐t t❤❡♦r❡♠✱ ❦❡r♥❡❧ ❞❡♥s✐t② ❡st✐♠❛t♦r✱ str♦♥❣❧②
♠✐①✐♥❣ r❛♥❞♦♠ ✜❡❧❞s✱ s♣❛t✐❛❧ ♣r♦❝❡ss❡s✳
❙❤♦rt t✐t❧❡✿ ❑❡r♥❡❧ ❞❡♥s✐t② ❡st✐♠❛t✐♦♥ ❢♦r r❛♥❞♦♠ ✜❡❧❞s✳
✶ ■♥tr♦❞✉❝t✐♦♥ ❛♥❞ ♠❛✐♥ r❡s✉❧t
❚❤❡ ❦❡r♥❡❧ ❞❡♥s✐t② ❡st✐♠❛t♦r ✐♥tr♦❞✉❝❡❞ ❜② ❘♦s❡♥❜❧❛tt ❬✷✵❪ ❛♥❞ P❛r③❡♥ ❬✶✽❪ ❤❛s r❡❝❡✐✈❡❞
❝♦♥s✐❞❡r❛❜❧❡ ❛tt❡♥t✐♦♥ ✐♥ ♥♦♥♣❛r❛♠❡tr✐❝ ❡st✐♠❛t✐♦♥ ♦❢ ♣r♦❜❛❜✐❧✐t② ❞❡♥s✐t✐❡s ❢♦r t✐♠❡
s❡r✐❡s✳ ■❢ (X
i)
i∈Z✐s ❛ st❛t✐♦♥❛r② s❡q✉❡♥❝❡ ♦❢ r❡❛❧ r❛♥❞♦♠ ✈❛r✐❛❜❧❡s ✇✐t❤ ❛ ♠❛r❣✐♥❛❧
❞❡♥s✐t② f t❤❡♥ t❤❡ ❦❡r♥❡❧ ❞❡♥s✐t② ❡st✐♠❛t♦r ♦❢ f ✐s ❞❡✜♥❡❞ ❢♦r ❛♥② ♣♦s✐t✐✈❡ ✐♥t❡❣❡r n
❛♥❞ ❛♥② x ✐♥ R ❜②
f
n(x) = 1 nb
nn
X
i=1
❑
x − X
ib
n✇❤❡r❡ ❑ ✐s ❛ ♣r♦❜❛❜✐❧✐t② ❦❡r♥❡❧ ❛♥❞ t❤❡ ❜❛♥❞✇✐❞t❤ b
n✐s ❛ ♣❛r❛♠❡t❡r ✇❤✐❝❤ ❝♦♥✈❡r❣❡s s❧♦✇❧② t♦ ③❡r♦ s✉❝❤ t❤❛t nb
n❣♦❡s t♦ ✐♥✜♥✐t② ✭t❤❡ ❜❛♥❞✇✐❞t❤ ❞❡t❡r♠✐♥❡s t❤❡ ❛♠♦✉♥t
♦❢ s♠♦♦t❤♥❡ss ♦❢ t❤❡ ❡st✐♠❛t♦r✮✳ ❋♦r s♠❛❧❧ b
n✇❡ ❣❡t ❛ ✈❡r② r♦✉❣❤ ❡st✐♠❛t❡ ❛♥❞ ❢♦r
❧❛r❣❡ b
n❛ s♠♦♦t❤ ❡st✐♠❛t❡✳ ❚❤❡ ❧✐t❡r❛t✉r❡ ❞❡❛❧✐♥❣ ✇✐t❤ t❤❡ ❛s②♠♣t♦t✐❝ ♣r♦♣❡rt✐❡s ♦❢ f
n✇❤❡♥ t❤❡ ♦❜s❡r✈❛t✐♦♥s (X
i)
i∈Z❛r❡ ✐♥❞❡♣❡♥❞❡♥t ✐s ✈❡r② ❡①t❡♥s✐✈❡ ✭s❡❡ ❙✐❧✈❡r♠❛♥ ❬✷✶❪✮✳
■♥ ♣❛rt✐❝✉❧❛r✱ P❛r③❡♥ ❬✶✽❪ ♣r♦✈❡❞ t❤❛t ✇❤❡♥ (X
i)
i∈Z✐s ✐✳✐✳❞✳ ❛♥❞ t❤❡ ❜❛♥❞✇✐❞t❤ b
n❣♦❡s t♦ ③❡r♦ s✉❝❤ t❤❛t nb
n❣♦❡s t♦ ✐♥✜♥✐t② t❤❡♥ (nb
n)
1/2(f
n(x
0) − E f
n(x
0)) ❝♦♥✈❡r❣❡s ✐♥
❞✐str✐❜✉t✐♦♥ t♦ t❤❡ ♥♦r♠❛❧ ❧❛✇ ✇✐t❤ ③❡r♦ ♠❡❛♥ ❛♥❞ ✈❛r✐❛♥❝❡ f (x
0) R
R
❑
2(t)dt✳ ❯♥❞❡r t❤❡ s❛♠❡ ❝♦♥❞✐t✐♦♥s ♦♥ t❤❡ ❜❛♥❞✇✐❞t❤✱ t❤✐s r❡s✉❧t ✇❛s r❡❝❡♥t❧② ❡①t❡♥❞❡❞ ❜② ❲✉ ❬✷✹❪ ❢♦r
❝❛✉s❛❧ ❧✐♥❡❛r ♣r♦❝❡ss❡s ✇✐t❤ ✐✳✐✳❞✳ ✐♥♥♦✈❛t✐♦♥s ❛♥❞ ❜② ❉❡❞❡❝❦❡r ❛♥❞ ▼❡r❧❡✈è❞❡ ❬✼❪ ❢♦r str♦♥❣❧② ♠✐①✐♥❣ s❡q✉❡♥❝❡s✳ Pr❡✈✐♦✉s❧②✱ ❇♦sq✱ ▼❡r❧❡✈è❞❡ ❛♥❞ P❡❧✐❣r❛❞ ❬✸❪ ❡st❛❜❧✐s❤❡❞ ❛
❝❡♥tr❛❧ ❧✐♠✐t t❤❡♦r❡♠ ❢♦r t❤❡ ❦❡r♥❡❧ ❞❡♥s✐t② ❡st✐♠❛t♦r f
n✇❤❡♥ t❤❡ s❡q✉❡♥❝❡ (X
i)
i∈Z✐s
❛ss✉♠❡❞ t♦ ❜❡ str♦♥❣❧② ♠✐①✐♥❣ ❜✉t t❤❡ ❜❛♥❞✇✐t❤ ♣❛r❛♠❡t❡r b
n✐s ❛ss✉♠❡❞ t♦ s❛t✐s❢② b
n≥ Cn
−1/3log n ✭❢♦r s♦♠❡ ♣♦s✐t✐✈❡ ❝♦♥st❛♥t C✮ ✇❤✐❝❤ ✐s str♦♥❣❡r t❤❛♥ t❤❡ ❜❛♥❞✇✐t❤
♣❛r❛♠❡t❡r ❛ss✉♠♣t✐♦♥ ✐♥ ❬✶✽❪✱ ❬✼❪ ❛♥❞ ❬✷✹❪✳ ■♥ t❤✐s ♣❛♣❡r✱ ✇❡ ❛r❡ ❣♦✐♥❣ t♦ ❡st❛❜❧✐s❤
P❛r③❡♥✬s ❝❡♥tr❛❧ ❧✐♠✐t t❤❡♦r❡♠ ✭s❡❡ ❚❤❡♦r❡♠ 1✮ ❢♦r r❛♥❞♦♠ ✈❛r✐❛❜❧❡s ✇❤✐❝❤ s❤♦✇ s♣❛t✐❛❧
✐♥t❡r❛❝t✐♦♥ ✭r❛♥❞♦♠ ✜❡❧❞s✮✳ ❚❤❡ ♣r♦❜❧❡♠ ✐s ♥♦t tr✐✈✐❛❧ s✐♥❝❡ Z
d❞♦❡s ♥♦t ❤❛✈❡ ❛ ♥❛t✉r❛❧
♦r❞❡r✐♥❣ ❢♦r d ≥ 2✳ ■♥ ♣❛rt✐❝✉❧❛r✱ t❤❡ ♠❛rt✐♥❣❛❧❡✲❞✐✛❡r❡♥❝❡ ♠❡t❤♦❞ ✭❲✉ ❬✷✹❪✮ ❢♦r t✐♠❡
s❡r✐❡s s❡❡♠s t♦ ❜❡ ❞✐✣❝✉❧t t♦ ❛♣♣❧② ❢♦r r❛♥❞♦♠ ✜❡❧❞s✳ ■♥ ♦r❞❡r t♦ ❡st❛❜❧✐s❤ ♦✉r ♠❛✐♥
r❡s✉❧t✱ ✇❡ ✉s❡ t❤❡ ▲✐♥❞❡❜❡r❣✬s ♠❡t❤♦❞ ✐♥tr♦❞✉❝❡❞ ✐♥ ✶✾✷✷ ❢♦r t❤❡ ♣r♦♦❢ ♦❢ t❤❡ ❝❡♥tr❛❧
❧✐♠✐t t❤❡♦r❡♠ ❢♦r ✐♥❞❡♣❡♥❞❡♥t r❛♥❞♦♠ ✈❛r✐❛❜❧❡s ❛♥❞ s✉❝❝❡ss❢✉❧❧② ❛❞❛♣t❡❞ ✐♥ t❤❡ s♣❛t✐❛❧
s❡tt✐♥❣ ❜② ❉❡❞❡❝❦❡r ❬✻❪✳ ❖✉r ❛♣♣r♦❛❝❤ s❡❡♠s t♦ ❜❡ ❜❡tt❡r t❤❛♥ t❤❡ ❇❡r♥st❡✐♥✬s s♠❛❧❧✲
❜❧♦❝❦✲❧❛r❣❡✲❜❧♦❝❦ t❡❝❤♥✐q✉❡ ❛♥❞ ❝♦✉♣❧✐♥❣ ❛r❣✉♠❡♥ts ✇✐❞❡❧② ✉s❡❞ ✐♥ ♣r❡✈✐♦✉s ✇♦r❦s ♦♥
♥♦♥♣❛r❛♠❡tr✐❝ ❡st✐♠❛t✐♦♥ ❢♦r s♣❛t✐❛❧ ♣r♦❝❡ss❡s ✭s❡❡ ❬✹❪✱ ❬✺❪✱ ❬✶✷❪✱ ❬✷✷❪✮ s✐♥❝❡ ✇❡ ❛r❡ ❛❜❧❡
t♦ ❛ss✉♠❡ ♦♥❧② ♠✐♥✐♠❛❧ ❝♦♥❞✐t✐♦♥s ♦♥ t❤❡ ❜❛♥❞✇✐❞t❤ ♣❛r❛♠❡t❡r ❛♥❞ ❛ s✐♠♣❧❡ ❝r✐t❡r✐♦♥
♦♥ t❤❡ str♦♥❣ ♠✐①✐♥❣ ❝♦❡✣❝✐❡♥ts ✇❤✐❝❤ ❞♦ ♥♦t ❞❡♣❡♥❞ ♦♥ t❤❡ ❜❛♥❞✇✐t❤✳ ❖✈❡r t❤❡ ❧❛st
❢❡✇ ②❡❛rs ♥♦♥♣❛r❛♠❡tr✐❝ ❡st✐♠❛t✐♦♥ ❢♦r r❛♥❞♦♠ ✜❡❧❞s ✭♦r s♣❛t✐❛❧ ♣r♦❝❡ss❡s✮ ✇❛s ❣✐✈❡♥
✐♥❝r❡❛s✐♥❣ ❛tt❡♥t✐♦♥ ✭s❡❡ ●✉②♦♥ ❬✶✶❪✮✳ ■♥ ❢❛❝t✱ s♣❛t✐❛❧ ❞❛t❛ ❛r✐s❡ ✐♥ ✈❛r✐♦✉s ❛r❡❛s ♦❢
r❡s❡❛r❝❤ ✐♥❝❧✉❞✐♥❣ ❡❝♦♥♦♠❡tr✐❝s✱ ✐♠❛❣❡ ❛♥❛❧②s✐s✱ ♠❡t❡♦r♦❧♦❣② ❛♥❞ ❣❡♦st❛t✐st✐❝s✳ ❙♦♠❡
❦❡② r❡❢❡r❡♥❝❡s ♦♥ ♥♦♥♣❛r❛♠❡tr✐❝ ❡st✐♠❛t✐♦♥ ❢♦r r❛♥❞♦♠ ✜❡❧❞s ❛r❡ ❇✐❛✉ ❬✶❪✱ ❈❛r❜♦♥ ❡t
❛❧✳ ❬✹❪✱ ❈❛r❜♦♥ ❡t ❛❧✳ ❬✺❪✱ ❍❛❧❧✐♥ ❡t ❛❧✳ ❬✶✷❪✱ ❬✶✸❪✱ ❚r❛♥ ❬✷✷❪✱ ❚r❛♥ ❛♥❞ ❨❛❦♦✇✐t③ ❬✷✸❪ ❛♥❞
❨❛♦ ❬✷✺❪ ✇❤♦ ❤❛✈❡ ✐♥✈❡st✐❣❛t❡❞ ♥♦♥♣❛r❛♠❡tr✐❝ ❞❡♥s✐t② ❡st✐♠❛t✐♦♥ ❢♦r r❛♥❞♦♠ ✜❡❧❞s ❛♥❞
✷
❇✐❛✉ ❛♥❞ ❈❛❞r❡ ❬✷❪✱ ❊❧ ▼❛❝❤❦♦✉r✐ ❬✾❪✱ ❊❧ ▼❛❝❤❦♦✉r✐ ❛♥❞ ❙t♦✐❝❛ ❬✶✵❪✱ ❍❛❧❧✐♥ ❡t ❛❧✳ ❬✶✹❪
❛♥❞ ▲✉ ❛♥❞ ❈❤❡♥ ❬✶✺❪✱ ❬✶✻❪ ✇❤♦ ❤❛✈❡ st✉❞✐❡❞ s♣❛t✐❛❧ ♣r❡❞✐❝t✐♦♥ ❛♥❞ s♣❛t✐❛❧ r❡❣r❡ss✐♦♥
❡st✐♠❛t✐♦♥✳
▲❡t d ❜❡ ❛ ♣♦s✐t✐✈❡ ✐♥t❡❣❡r ❛♥❞ ❧❡t (X
i)
i∈Zd❜❡ ❛ ✜❡❧❞ ♦❢ ✐❞❡♥t✐❝❛❧❧② ❞✐str✐❜✉t❡❞ r❡❛❧
r❛♥❞♦♠ ✈❛r✐❛❜❧❡s ✇✐t❤ ❛ ♠❛r❣✐♥❛❧ ❞❡♥s✐t② f ✳ ●✐✈❡♥ t✇♦ σ ✲❛❧❣❡❜r❛s U ❛♥❞ V ♦❢ F ✱
❞✐✛❡r❡♥t ♠❡❛s✉r❡s ♦❢ t❤❡✐r ❞❡♣❡♥❞❡♥❝❡ ❤❛✈❡ ❜❡❡♥ ❝♦♥s✐❞❡r❡❞ ✐♥ t❤❡ ❧✐t❡r❛t✉r❡✳ ❲❡ ❛r❡
✐♥t❡r❡st❡❞ ❜② ♦♥❡ ♦❢ t❤❡♠✳ ❚❤❡ α✲♠✐①✐♥❣ ❝♦❡✣❝✐❡♥t ❤❛s ❜❡❡♥ ✐♥tr♦❞✉❝❡❞ ❜② ❘♦s❡♥❜❧❛tt
❬✷✵❪ ❞❡✜♥❡❞ ❜②
α( U , V ) = sup {| P (A ∩ B) − P (A) P (B ) | , A ∈ U , B ∈ V} .
■♥ t❤❡ s❡q✉❡❧✱ ✇❡ ❝♦♥s✐❞❡r t❤❡ str♦♥❣ ♠✐①✐♥❣ ❝♦❡✣❝✐❡♥ts α
1,∞(n) ❞❡✜♥❡❞ ❢♦r ❡❛❝❤ ♣♦s✐✲
t✐✈❡ ✐♥t❡❣❡r n ❜②
α
1,∞(n) = sup { α(σ(X
k), F
Γ), k ∈ Z
d, Γ ⊂ Z
d, ρ(Γ, { k } ) ≥ n } ,
✇❤❡r❡ F
Γ= σ(X
i; i ∈ Γ) ❛♥❞ t❤❡ ❞✐st❛♥❝❡ ρ ✐s ❞❡✜♥❡❞ ❢♦r ❛♥② s✉❜s❡ts Γ
1❛♥❞ Γ
2♦❢ Z
d❜② ρ(Γ
1, Γ
2) = min {| i − j | , i ∈ Γ
1, j ∈ Γ
2} ✇✐t❤ | i − j | = max
1≤s≤d| i
s− j
s|
❢♦r ❛♥② i ❛♥❞ j ✐♥ Z
d✳ ❲❡ s❛② t❤❛t t❤❡ r❛♥❞♦♠ ✜❡❧❞ (X
i)
i∈Zd✐s str♦♥❣❧② ♠✐①✐♥❣ ✐❢
lim
n→+∞α
1,∞(n) = 0✳ ❚❤❡ ❝❧❛ss ♦❢ ♠✐①✐♥❣ r❛♥❞♦♠ ✜❡❧❞s ✐♥ t❤❡ ❛❜♦✈❡ s❡♥s❡ ✐s ✈❡r②
❧❛r❣❡ ✭♦♥❡ ❝❛♥ r❡❢❡r t♦ ●✉②♦♥ ❬✶✶❪ ♦r ❉♦✉❦❤❛♥ ❬✽❪ ❢♦r ❡①❛♠♣❧❡s✮ ❛♥❞ ✇❡ r❡❝❛❧❧ t❤❛t
❉❡❞❡❝❦❡r ❬✻❪ ♦❜t❛✐♥❡❞ ❛ ❝❡♥tr❛❧ ❧✐♠✐t t❤❡♦r❡♠ ❢♦r t❤❡ st❛t✐♦♥❛r② r❛♥❞♦♠ ✜❡❧❞ (X
i)
i∈Zd♣r♦✈✐❞❡❞ t❤❛t X
0❤❛s ③❡r♦ ♠❡❛♥ ❛♥❞ ✜♥✐t❡ ✈❛r✐❛♥❝❡ ❛♥❞
X
k∈Zd
Z
α1,∞(|k|) 0Q
2X0(u)du < + ∞
✇❤❡r❡ Q
X0✐s t❤❡ q✉❛♥t✐❧❡ ❢✉♥❝t✐♦♥ ❞❡✜♥❡❞ ❢♦r ❛♥② u ✐♥ [0, 1] ❜② Q
X0(u) = inf { t ≥ 0 ; P ( | X
0| > t) ≤ u } .
❲❡ ❝♦♥s✐❞❡r t❤❡ ❞❡♥s✐t② ❡st✐♠❛t♦r ♦❢ f ❞❡✜♥❡❞ ❢♦r ❛♥② ♣♦s✐t✐✈❡ ✐♥t❡❣❡r n ❛♥❞ ❛♥② x ✐♥
R ❜②
f
n(x) = 1 n
db
nX
i∈Λn
❑
x − X
ib
n✇❤❡r❡ b
n✐s t❤❡ ❜❛♥❞✇✐❞t❤ ♣❛r❛♠❡t❡r✱ Λ
n❞❡♥♦t❡s t❤❡ s❡t { 1, ..., n }
d❛♥❞ ❑ ✐s ❛ ♣r♦❜❛❜✐❧✲
✐t② ❦❡r♥❡❧✳ ❖✉r ❛✐♠ ✐s t♦ ♣r♦✈✐❞❡ ❛ s✉✣❝✐❡♥t ❝♦♥❞✐t✐♦♥ ♦♥ t❤❡ str♦♥❣ ♠✐①✐♥❣ ❝♦❡✣❝✐❡♥ts α
1,∞(n) ❢♦r (n
db
n)
1/2(f
n(x
i) − E f
n(x
i))
1≤i≤k, (x
i)
1≤i≤k∈ R
k, k ∈ N
∗, t♦ ❝♦♥✈❡r❣❡ ✐♥ ❧❛✇
✸
t♦ ❛ ♠✉❧t✐✈❛r✐❛t❡ ♥♦r♠❛❧ ❞✐str✐❜✉t✐♦♥ ✭❚❤❡♦r❡♠ 1✮ ✉♥❞❡r ♠✐♥✐♠❛❧ ❝♦♥❞✐t✐♦♥s ♦♥ t❤❡
❜❛♥❞✇✐❞t❤s ✭t❤❛t ✐s b
n❣♦❡s t♦ ③❡r♦ ❛♥❞ n
db
n❣♦❡s t♦ ✐♥✜♥✐t②✮✳
❲❡ ❝♦♥s✐❞❡r t❤❡ ❢♦❧❧♦✇✐♥❣ ❛ss✉♠♣t✐♦♥s✿
✭❆✶✮ ❚❤❡ ♠❛r❣✐♥❛❧ ♣r♦❜❛❜✐❧✐t② ❞✐str✐❜✉t✐♦♥ ♦❢ ❡❛❝❤ X
k✐s ❛❜s♦❧✉t❡❧② ❝♦♥t✐♥✉♦✉s ✇✐t❤
❝♦♥t✐♥✉♦✉s ♣♦s✐t✐✈❡ ❞❡♥s✐t② ❢✉♥❝t✐♦♥ f ✳
✭❆✷✮ ❚❤❡ ❥♦✐♥t ♣r♦❜❛❜✐❧✐t② ❞✐str✐❜✉t✐♦♥ ♦❢ ❡❛❝❤ (X
0, X
k) ✐s ❛❜s♦❧✉t❡❧② ❝♦♥t✐♥✉♦✉s ✇✐t❤
❝♦♥t✐♥✉♦✉s ❥♦✐♥t ❞❡♥s✐t② f
0,k✳
✭❆✸✮ ❑ ✐s ❛ ♣r♦❜❛❜✐❧✐t② ❦❡r♥❡❧ ✇✐t❤ ❝♦♠♣❛❝t s✉♣♣♦rt ❛♥❞ R
R
❑
2(u) du < ∞✳
✭❆✹✮ ❚❤❡ ❜❛♥❞✇✐❞t❤ b
n❝♦♥✈❡r❣❡s t♦ ③❡r♦ ❛♥❞ n
db
n❣♦❡s t♦ ✐♥✜♥✐t②✳
❖✉r ♠❛✐♥ r❡s✉❧t ✐s t❤❡ ❢♦❧❧♦✇✐♥❣✳
❚❤❡♦r❡♠ ✶ ❆ss✉♠❡ t❤❛t ✭❆✶✮✱ ✭❆✷✮✱ ✭❆✸✮ ❛♥❞ ✭❆✹✮ ❤♦❧❞ ❛♥❞
+∞
X
m=1
m
2d−1α
1,∞(m) < + ∞ . ✭✶✮
❚❤❡♥ ❢♦r ❛♥② ♣♦s✐t✐✈❡ ✐♥t❡❣❡r k ❛♥❞ ❛♥② ❞✐st✐♥❝t ♣♦✐♥ts x
1, ..., x
k✐♥ R ✱
(n
db
n)
1/2
f
n(x
1) − E f
n(x
1)
✳✳✳
f
n(x
k) − E f
n(x
k)
−−−−−→
Ln→+∞
N (0, V ) ✭✷✮
✇❤❡r❡ V ✐s ❛ ❞✐❛❣♦♥❛❧ ♠❛tr✐① ✇✐t❤ ❞✐❛❣♦♥❛❧ ❡❧❡♠❡♥ts v
ii= f (x
i) R
R
❑
2(u)du ✳
❘❡♠❛r❦ ✶✳ ❆ r❡♣❧❛❝❡♠❡♥t ♦❢ E f
n(x
i) ❜② f(x
i) ❢♦r ❛♥② 1 ≤ i ≤ k ✐♥ ✭ 2 ✮ ✐s ❛ ❝❧❛ss✐❝❛❧
♣r♦❜❧❡♠ ✐♥ ❞❡♥s✐t② ❡st✐♠❛t✐♦♥ t❤❡♦r②✳ ❋♦r ❡①❛♠♣❧❡✱ ✐❢ f ✐s ❛ss✉♠❡❞ t♦ ❜❡ ▲✐♣s❝❤✐t③ ❛♥❞
✐❢ R
R
| u ||❑ (u) | du < ∞ t❤❡♥ | E f
n(x
i) − f(x
i) | = O(b
n) ❛♥❞ t❤✉s t❤❡ ❝❡♥t❡r✐♥❣ E f
n(x
i)
♠❛② ❜❡ ❝❤❛♥❣❡❞ t♦ f(x
i) ✇✐t❤♦✉t ❛✛❡❝t✐♥❣ t❤❡ ❛❜♦✈❡ r❡s✉❧t ♣r♦✈✐❞❡❞ t❤❛t n
db
3n❝♦♥✲
✈❡r❣❡s t♦ ③❡r♦✳
❘❡♠❛r❦ ✷✳ ❚❤❡♦r❡♠ 1 ✐s ❛♥ ❡①t❡♥s✐♦♥ ♦❢ ❚❤❡♦r❡♠ ✸✳✶ ❜② ❇♦sq✱ ▼❡r❧❡✈è❞❡ ❛♥❞
P❡❧✐❣r❛❞ ❬✸❪✳ ■♥ ❢❛❝t✱ ✉s✐♥❣ ❛ ❞✐✛❡r❡♥t ❛♣♣r♦❛❝❤✱ t❤❡ ❛✉t❤♦rs ♦❜t❛✐♥❡❞ t❤❡ s❛♠❡ r❡s✉❧t
❢♦r d = 1 ✇✐t❤ ❛♥ ❛❞❞✐t✐♦♥❛❧ ❝♦♥❞✐t✐♦♥ ♦♥ t❤❡ ❜❛♥❞✇✐t❤ ♣❛r❛♠❡t❡r ✭t❤❛t ✐s✱ t❤❡r❡ ❡①✐sts
❛ ♣♦s✐t✐✈❡ ❝♦♥st❛♥t C s✉❝❤ t❤❛t b
n≥ C n
−1/3log n ✮✳ ❍♦✇❡✈❡r✱ t❤❡ ❝♦♥❞✐t✐♦♥ ✭✶✮ ✇✐t❤
d = 1 ✐s s❧✐❣❤t❧② ♠♦r❡ r❡str✐❝t✐✈❡ t❤❛♥ t❤❡ ❝♦♥❞✐t✐♦♥ P
m>n
α
1,∞(m) = o(n
−1) ♦❜t❛✐♥❡❞
❜② ❉❡❞❡❝❦❡r ❛♥❞ ▼❡r❧❡✈è❞❡ ✭❬✼❪✱ ❈♦r♦❧❧❛r② ✹✮✳ ❲❡ ❝♦♥❥❡❝t✉r❡ t❤❛t ❚❤❡♦r❡♠ ✶ st✐❧❧ ❤♦❧❞s
✉♥❞❡r t❤❡ ❝♦♥❞✐t✐♦♥ P
m>n
m
d−1α
1,∞(m) = o(n
−d) ✳
✹
✷ Pr♦♦❢s
Pr♦♦❢ ♦❢ ❚❤❡♦r❡♠ ✶✳ ❲✐t❤♦✉t ❧♦ss ♦❢ ❣❡♥❡r❛❧✐t②✱ ✇❡ ❝♦♥s✐❞❡r ♦♥❧② t❤❡ ❝❛s❡ k = 2
❛♥❞ ✇❡ r❡❢❡r t♦ x
1❛♥❞ x
2❛s x ❛♥❞ y ✭x 6 = y✮✳ ▲❡t λ
1❛♥❞ λ
2❜❡ t✇♦ ❝♦♥st❛♥ts s✉❝❤
t❤❛t λ
21+ λ
22= 1 ❛♥❞ ❞❡♥♦t❡
S
n= λ
1(n
db
n)
1/2(f
n(x) − E f
n(x)) + λ
2(n
db
n)
1/2(f
n(y) − E f
n(y)) = X
i∈Λn
∆
in
d/2✇❤❡r❡ ∆
i= λ
1Z
i(x) + λ
2Z
i(y) ❛♥❞ ❢♦r ❛♥② z ✐♥ R ✱ Z
i(z) = 1
√ b
n❑
z − X
ib
n− E ❑
z − X
ib
n.
❲❡ ❝♦♥s✐❞❡r t❤❡ ♥♦t❛t✐♦♥s
η = (λ
21f (x) + λ
22f(y))σ
2❛♥❞ σ
2= Z
R
❑
2(u)du. ✭✸✮
❚❤❡ ♣r♦♦❢ ♦❢ t❤❡ ❢♦❧❧♦✇✐♥❣ t❡❝❤♥✐❝❛❧ r❡s✉❧t ✐s ♣♦st♣♦♥❡❞ t♦ t❤❡ ❛♥♥❡①✳
▲❡♠♠❛ ✶ E (∆
20) ❝♦♥✈❡r❣❡s t♦ η ❛♥❞ E | ∆
0∆
i| = O(b
n) ❢♦r ❛♥② i ✐♥ Z
d\{ 0 }✳
■♥ ♦r❞❡r t♦ ♣r♦✈❡ t❤❡ ❝♦♥✈❡r❣❡♥❝❡ ✐♥ ❞✐str✐❜✉t✐♦♥ ♦❢ S
nt♦ √ ητ
0✇❤❡r❡ τ
0∼ N (0, 1)✱
✇❡ ❛r❡ ❣♦✐♥❣ t♦ ❢♦❧❧♦✇ t❤❡ ▲✐♥❞❡❜❡r❣✬s ♠❡t❤♦❞ ✉s❡❞ ✐♥ t❤❡ ♣r♦♦❢ ♦❢ t❤❡ ❝❡♥tr❛❧ ❧✐♠✐t t❤❡♦r❡♠ ❢♦r st❛t✐♦♥❛r② r❛♥❞♦♠ ✜❡❧❞s ❜② ❉❡❞❡❝❦❡r ❬✻❪✳ ▲❡t ✉s ♥♦t❡ t❤❛t s❡✈❡r❛❧ ♣r❡✈✐✲
♦✉s ❛s②♠♣t♦t✐❝ r❡s✉❧ts ❢♦r ❦❡r♥❡❧ ❞❡♥s✐t② ❡st✐♠❛t❡s ✐♥ t❤❡ ❝♦♥t❡①t ♦❢ s♣❛t✐❛❧ ♣r♦❝❡ss❡s
✇❡r❡ ❡st❛❜❧✐s❤❡❞ ✉s✐♥❣ t❤❡ s♦✲❝❛❧❧❡❞ ❇❡r♥st❡✐♥✬s s♠❛❧❧✲❜❧♦❝❦✲❧❛r❣❡✲❜❧♦❝❦ t❡❝❤♥✐q✉❡ ❛♥❞
❝♦✉♣❧✐♥❣ ❛r❣✉♠❡♥ts ✇❤✐❝❤ ❧❡❛❞ t♦ r❡str✐❝t✐✈❡ ❝♦♥❞✐t✐♦♥s ♦♥ t❤❡ ❜❛♥❞✇✐t❤ ♣❛r❛♠❡t❡r
✭s❡❡ ❢♦r ❡①❛♠♣❧❡ ❬✹❪✱ ❬✺❪✱ ❬✶✷❪✱ ❬✷✷❪✮✳ ❖✉r ❛♣♣r♦❛❝❤ s❡❡♠s t♦ ❜❡ ❜❡tt❡r s✐♥❝❡ ✇❡ ♦❜t❛✐♥
❛ ❝❡♥tr❛❧ ❧✐♠✐t t❤❡♦r❡♠ ✇❤❡♥ t❤❡ ❜❛♥❞✇✐t❤ s❛t✐s✜❡s ♦♥❧② ❆ss✉♠♣t✐♦♥ ✭❆✹✮✳
▲❡t µ ❜❡ t❤❡ ❧❛✇ ♦❢ t❤❡ st❛t✐♦♥❛r② r❡❛❧ r❛♥❞♦♠ ✜❡❧❞ (X
k)
k∈Zd❛♥❞ ❝♦♥s✐❞❡r t❤❡ ♣r♦❥❡❝✲
t✐♦♥ π
0❢r♦♠ R
Zdt♦ R ❞❡✜♥❡❞ ❜② π
0(ω) = ω
0❛♥❞ t❤❡ ❢❛♠✐❧② ♦❢ tr❛♥s❧❛t✐♦♥ ♦♣❡r❛t♦rs (T
k)
k∈Zd❢r♦♠ R
Zdt♦ R
Zd❞❡✜♥❡❞ ❜② (T
k(ω))
i= ω
i+k❢♦r ❛♥② k ∈ Z
d❛♥❞ ❛♥② ω ✐♥ R
Zd✳
❉❡♥♦t❡ ❜② B t❤❡ ❇♦r❡❧ σ✲❛❧❣❡❜r❛ ♦❢ R ✳ ❚❤❡ r❛♥❞♦♠ ✜❡❧❞ (π
0◦ T
k)
k∈Zd❞❡✜♥❡❞ ♦♥ t❤❡
♣r♦❜❛❜✐❧✐t② s♣❛❝❡ ( R
Zd, B
Zd, µ) ✐s st❛t✐♦♥❛r② ✇✐t❤ t❤❡ s❛♠❡ ❧❛✇ ❛s (X
k)
k∈Zd✱ ❤❡♥❝❡✱ ✇✐t❤✲
♦✉t ❧♦ss ♦❢ ❣❡♥❡r❛❧✐t②✱ ♦♥❡ ❝❛♥ s✉♣♣♦s❡ t❤❛t (Ω, F , P ) = ( R
Zd, B
Zd, µ) ❛♥❞ X
k= π
0◦ T
k✳
❖♥ t❤❡ ❧❛tt✐❝❡ Z
d✇❡ ❞❡✜♥❡ t❤❡ ❧❡①✐❝♦❣r❛♣❤✐❝ ♦r❞❡r ❛s ❢♦❧❧♦✇s✿ ✐❢ i = (i
1, ..., i
d) ❛♥❞
j = (j
1, ..., j
d) ❛r❡ ❞✐st✐♥❝t ❡❧❡♠❡♥ts ♦❢ Z
d✱ t❤❡ ♥♦t❛t✐♦♥ i <
❧❡①j ♠❡❛♥s t❤❛t ❡✐t❤❡r
✺
i
1< j
1♦r ❢♦r s♦♠❡ p ✐♥ { 2, 3, ..., d }✱ i
p< j
p❛♥❞ i
q= j
q❢♦r 1 ≤ q < p✳ ▲❡t t❤❡ s❡ts { V
iM; i ∈ Z
d, M ∈ N
∗} ❜❡ ❞❡✜♥❡❞ ❛s ❢♦❧❧♦✇s✿
V
i1= { j ∈ Z
d; j <
❧❡①i } ,
❛♥❞ ❢♦r M ≥ 2
V
iM= V
i1∩ { j ∈ Z
d; | i − j | ≥ M } ✇❤❡r❡ | i − j | = max
1≤l≤d
| i
l− j
l| .
❋♦r ❛♥② s✉❜s❡t Γ ♦❢ Z
d❞❡✜♥❡ F
Γ= σ(X
i; i ∈ Γ) ❛♥❞ s❡t E
M(X
i) = E (X
i|F
ViM), M ∈ N
∗.
▲❡t g ❜❡ ❛ ♦♥❡ t♦ ♦♥❡ ♠❛♣ ❢r♦♠ [1, M ] ∩ N
∗t♦ ❛ ✜♥✐t❡ s✉❜s❡t ♦❢ Z
d❛♥❞ (ξ
i)
i∈Zd❛ r❡❛❧
r❛♥❞♦♠ ✜❡❧❞✳ ❋♦r ❛❧❧ ✐♥t❡❣❡rs k ✐♥ [1, M ] ✱ ✇❡ ❞❡♥♦t❡
S
g(k)(ξ) =
k
X
i=1
ξ
g(i)❛♥❞ S
g(k)c(ξ) =
M
X
i=k
ξ
g(i)✇✐t❤ t❤❡ ❝♦♥✈❡♥t✐♦♥ S
g(0)(ξ) = S
g(M+1)c(ξ) = 0✳ ❚♦ ❞❡s❝r✐❜❡ t❤❡ s❡t Λ
n= { 1, ..., n }
d✱ ✇❡
❞❡✜♥❡ t❤❡ ♦♥❡ t♦ ♦♥❡ ♠❛♣ g ❢r♦♠ [1, n
d] ∩ N
∗t♦ Λ
n❜②✿ g ✐s t❤❡ ✉♥✐q✉❡ ❢✉♥❝t✐♦♥ s✉❝❤
t❤❛t g(k) <
❧❡①g(l) ❢♦r 1 ≤ k < l ≤ n
d✳ ❋r♦♠ ♥♦✇ ♦♥✱ ✇❡ ❝♦♥s✐❞❡r ❛ ✜❡❧❞ (τ
i)
i∈Zd♦❢
✐✳✐✳❞✳ r❛♥❞♦♠ ✈❛r✐❛❜❧❡s ✐♥❞❡♣❡♥❞❡♥t ♦❢ (X
i)
i∈Zds✉❝❤ t❤❛t τ
0❤❛s t❤❡ st❛♥❞❛r❞ ♥♦r♠❛❧
❧❛✇ N (0, 1) ✳ ❲❡ ✐♥tr♦❞✉❝❡ t❤❡ ✜❡❧❞s Y ❛♥❞ γ ❞❡✜♥❡❞ ❢♦r ❛♥② i ✐♥ Z
d❜② Y
i= ∆
in
d/2❛♥❞ γ
i= τ
i√ η n
d/2✇❤❡r❡ η ✐s ❞❡✜♥❡❞ ❜② ✭ 3 ✮✳
▲❡t h ❜❡ ❛♥② ❢✉♥❝t✐♦♥ ❢r♦♠ R t♦ R ✳ ❋♦r 0 ≤ k ≤ l ≤ n
d+ 1 ✱ ✇❡ ✐♥tr♦❞✉❝❡
h
k,l(Y ) = h(S
g(k)(Y ) + S
g(l)c(γ)) ✳ ❲✐t❤ t❤❡ ❛❜♦✈❡ ❝♦♥✈❡♥t✐♦♥ ✇❡ ❤❛✈❡ t❤❛t h
k,nd+1(Y ) = h(S
g(k)(Y )) ❛♥❞ ❛❧s♦ h
0,l(Y ) = h(S
g(l)c(γ))✳ ■♥ t❤❡ s❡q✉❡❧✱ ✇❡ ✇✐❧❧ ♦❢t❡♥ ✇r✐t❡ h
k,l✐♥st❡❛❞
♦❢ h
k,l(Y )✳ ❲❡ ❞❡♥♦t❡ ❜② B
14( R ) t❤❡ ✉♥✐t ❜❛❧❧ ♦❢ C
b4( R )✿ h ❜❡❧♦♥❣s t♦ B
14( R ) ✐❢ ❛♥❞ ♦♥❧②
✐❢ ✐t ❜❡❧♦♥❣s t♦ C
4( R ) ❛♥❞ s❛t✐s✜❡s max
0≤i≤4k h
(i)k
∞≤ 1✳
■t s✉✣❝❡s t♦ ♣r♦✈❡ t❤❛t ❢♦r ❛❧❧ h ✐♥ B
14( R )✱
E h S
g(nd)(Y )
−−−−−→
n→+∞
E (h (τ
0√ η)) .
✻
❲❡ ✉s❡ ▲✐♥❞❡❜❡r❣✬s ❞❡❝♦♠♣♦s✐t✐♦♥✿
E h S
g(nd)(Y )
− h (τ
0√ η)
=
nd
X
k=1
E (h
k,k+1− h
k−1,k) .
◆♦✇✱
h
k,k+1− h
k−1,k= h
k,k+1− h
k−1,k+1+ h
k−1,k+1− h
k−1,k.
❆♣♣❧②✐♥❣ ❚❛②❧♦r✬s ❢♦r♠✉❧❛ ✇❡ ❣❡t t❤❛t✿
h
k,k+1− h
k−1,k+1= Y
g(k)h
′k−1,k+1+ 1
2 Y
g(k)2h
′′k−1,k+1+ R
k❛♥❞
h
k−1,k+1− h
k−1,k= − γ
g(k)h
′k−1,k+1− 1
2 γ
g(k)2h
′′k−1,k+1+ r
k✇❤❡r❡ | R
k| ≤ Y
g(k)2(1 ∧ | Y
g(k)| ) ❛♥❞ | r
k| ≤ γ
g(k)2(1 ∧ | γ
g(k)| )✳ ❙✐♥❝❡ (Y, τ
i)
i6=g(k)✐s ✐♥❞❡♣❡♥✲
❞❡♥t ♦❢ τ
g(k)✱ ✐t ❢♦❧❧♦✇s t❤❛t E
γ
g(k)h
′k−1,k+1= 0 ❛♥❞ E
γ
g(k)2h
′′k−1,k+1= E η
n
dh
′′k−1,k+1❍❡♥❝❡✱ ✇❡ ♦❜t❛✐♥
E h(S
g(nd)(Y )) − h (τ
0√ η)
=
nd
X
k=1
E (Y
g(k)h
′k−1,k+1)
+
nd
X
k=1
E
Y
g(k)2− η n
dh
′′k−1,k+12
!
+
nd
X
k=1
E (R
k+ r
k) .
▲❡t 1 ≤ k ≤ n
d❜❡ ✜①❡❞✳ ◆♦t✐♥❣ t❤❛t ∆
0✐s ❜♦✉♥❞❡❞ ❜② 4 k❑k
∞/ √
b
n❛♥❞ ❛♣♣❧②✐♥❣
▲❡♠♠❛ 1 ✱ ✇❡ ❞❡r✐✈❡
E | R
k| ≤ E | ∆
0|
3n
3d/2= O
1 (n
3db
n)
1/2❛♥❞
E | r
k| ≤ E | γ
0|
3n
3d/2≤ η
3/2E | τ
0|
3n
3d/2= O
1 n
3d/2.
❈♦♥s❡q✉❡♥t❧②✱ ✇❡ ♦❜t❛✐♥
nd
X
k=1
E ( | R
k| + | r
k| ) = O
1
(n
db
n)
1/2+ 1 n
d/2= o(1).
✼
◆♦✇✱ ✐t ✐s s✉✣❝✐❡♥t t♦ s❤♦✇
n→+∞
lim
nd
X
k=1
E (Y
g(k)h
′k−1,k+1) + E
Y
g(k)2− η n
dh
′′k−1,k+12
!!
= 0. ✭✹✮
❋✐rst✱ ✇❡ ❢♦❝✉s ♦♥ P
ndk=1
E Y
g(k)h
′k−1,k+1✳ ❋♦r ❛❧❧ M ✐♥ N
∗❛♥❞ ❛❧❧ ✐♥t❡❣❡r k ✐♥ [1, n
d] ✱
✇❡ ❞❡✜♥❡
E
kM= g([1, k] ∩ N
∗) ∩ V
g(k)M❛♥❞ S
g(k)M(Y ) = X
i∈EkM
Y
i.
❋♦r ❛♥② ❢✉♥❝t✐♦♥ Ψ ❢r♦♠ R t♦ R ✱ ✇❡ ❞❡✜♥❡ Ψ
Mk−1,l= Ψ(S
g(k)M(Y ) + S
g(l)c(γ)) ✭✇❡ ❛r❡
❣♦✐♥❣ t♦ ❛♣♣❧② t❤✐s ♥♦t❛t✐♦♥ t♦ t❤❡ s✉❝❝❡ss✐✈❡ ❞❡r✐✈❛t✐✈❡s ♦❢ t❤❡ ❢✉♥❝t✐♦♥ h✮✳
❋♦r ❛♥② ✐♥t❡❣❡r n✱ ✇❡ ❞❡✜♥❡
m
n= max
b
n−12d,
1 b
2nX
|i|>
» b
−12d n
–
| i |
dα
1,∞( | i | )
1 2d
+ 1
✇❤❡r❡ [ . ] ❞❡♥♦t❡s t❤❡ ✐♥t❡❣❡r ♣❛rt ❢✉♥❝t✐♦♥✳ ❚❤❡ ❢♦❧❧♦✇✐♥❣ t❡❝❤♥✐❝❛❧ ❧❡♠♠❛ ✐s t❤❡
s♣❛t✐❛❧ ✈❡rs✐♦♥ ♦❢ ❛ r❡s✉❧t ❜② ❇♦sq✱ ▼❡r❧❡✈è❞❡ ❛♥❞ P❡❧✐❣r❛❞ ✭❬✸❪✱ ♣❛❣❡s ✽✽✲✽✾✮✳ ■♥ ♦r❞❡r t♦ ❜❡ s❡❧❢✲❝♦♥t❛✐♥❡❞✱ t❤❡ ♣r♦♦❢ ✐s ❞♦♥❡ ✐♥ t❤❡ ❛♣♣❡♥❞✐①✳
▲❡♠♠❛ ✷ ❯♥❞❡r ❆ss✉♠♣t✐♦♥ ✭❆✹✮ ❛♥❞ t❤❡ ♠✐①✐♥❣ ❝♦♥❞✐t✐♦♥ (1) ✱ ✇❡ ❤❛✈❡
m
dn→ ∞ , m
dnb
n→ 0 ❛♥❞ 1 m
dnb
nX
|i|>mn
| i |
dα
1,∞( | i | ) → 0. ✭✺✮
❖✉r ❛✐♠ ✐s t♦ s❤♦✇ t❤❛t
n→+∞
lim
nd
X
k=1
E
Y
g(k)h
′k−1,k+1− Y
g(k)S
g(k−1)(Y ) − S
g(k)mn(Y )
h
′′k−1,k+1= 0.
❋✐rst✱ ✇❡ ✉s❡ t❤❡ ❞❡❝♦♠♣♦s✐t✐♦♥
Y
g(k)h
′k−1,k+1= Y
g(k)h
′k−1,k+1mn+ Y
g(k)h
′k−1,k+1− h
′k−1,k+1mn.
❲❡ ❝♦♥s✐❞❡r ❛ ♦♥❡ t♦ ♦♥❡ ♠❛♣ m ❢r♦♠ [1, | E
kmn| ] ∩ N
∗t♦ E
kmn❛♥❞ s✉❝❤ t❤❛t | m(i) − g(k) | ≤ | m(i − 1) − g(k) |✳ ❚❤✐s ❝❤♦✐❝❡ ♦❢ m ❡♥s✉r❡s t❤❛t S
m(i)(Y ) ❛♥❞ S
m(i−1)(Y ) ❛r❡
F
V|m(i)−g(k)|g(k)
✲♠❡❛s✉r❛❜❧❡✳ ❚❤❡ ❢❛❝t t❤❛t γ ✐s ✐♥❞❡♣❡♥❞❡♥t ♦❢ Y ✐♠♣❧② t❤❛t E
Y
g(k)h
′S
g(k+1)c(γ )
= 0.
✽
❚❤❡r❡❢♦r❡
E
Y
g(k)h
′k−1,k+1mn=
|Emnk |
X
i=1
E Y
g(k)(θ
i− θ
i−1)
✭✻✮
✇❤❡r❡ θ
i= h
′S
m(i)(Y ) + S
g(k+1)c(γ)
✳
❙✐♥❝❡ S
m(i)(Y ) ❛♥❞ S
m(i−1)(Y ) ❛r❡ F
V|m(i)−g(k)|g(k)
✲♠❡❛s✉r❛❜❧❡✱ ✇❡ ❝❛♥ t❛❦❡ t❤❡ ❝♦♥❞✐t✐♦♥❛❧
❡①♣❡❝t❛t✐♦♥ ♦❢ Y
g(k)✇✐t❤ r❡s♣❡❝t t♦ F
V|m(i)−g(k)|g(k)
✐♥ t❤❡ r✐❣❤t ❤❛♥❞ s✐❞❡ ♦❢ ✭6✮✳ ❖♥ t❤❡
♦t❤❡r ❤❛♥❞ t❤❡ ❢✉♥❝t✐♦♥ h
′✐s 1✲▲✐♣s❝❤✐t③✱ ❤❡♥❝❡
| θ
i− θ
i−1| ≤ | Y
m(i)| .
❈♦♥s❡q✉❡♥t❧②✱
E Y
g(k)(θ
i− θ
i−1)
≤ E | Y
m(i)E
|m(i)−g(k)|Y
g(k)|
❛♥❞
E
Y
g(k)h
′k−1,k+1mn≤
|Emnk |
X
i=1
E | Y
m(i)E
|m(i)−g(k)|(Y
g(k)) | .
❍❡♥❝❡✱
nd
X
k=1
E
Y
g(k)h
′k−1,k+1mn≤ 1 n
dnd
X
k=1
|Emnk |
X
i=1
E | ∆
m(i)E
|m(i)−g(k)|(∆
g(k)) |
≤ X
|j|≥mn
k ∆
jE
|j|(∆
0) k
1.
❋♦r ❛♥② j ✐♥ Z
d✱ ✇❡ ❤❛✈❡
k ∆
jE
|j|(∆
0) k
1= ❈♦✈
| ∆
j| I
E|j|(∆0)≥0
− I
E|j|(∆0)<0
, ∆
0.
❙♦✱ ❛♣♣❧②✐♥❣ ❘✐♦✬s ❝♦✈❛r✐❛♥❝❡ ✐♥❡q✉❛❧✐t② ✭❝❢✳ ❬✶✾❪✱ ❚❤❡♦r❡♠ ✶✳✶✮✱ ✇❡ ♦❜t❛✐♥
k ∆
jE
|j|(∆
0) k
1≤ 4
Z
α1,∞(|j|) 0Q
2∆0(u)du
✇❤❡r❡ Q
∆0✐s ❞❡✜♥❡❞ ❜② Q
∆0(u) = inf { t ≥ 0 ; P ( | ∆
0| > t) ≤ u } ❢♦r ❛♥② u ✐♥ [0, 1]✳
❙✐♥❝❡ ∆
0✐s ❜♦✉♥❞❡❞ ❜② 4 k❑k
∞/ √
b
n✱ ✇❡ ❤❛✈❡
Q
∆0(u) ≤ 4 k❑k
∞√ b
n❛♥❞ k ∆
jE
|j|(∆
0) k
1≤ 64 k❑k
2∞b
nα
1,∞( | j | ).
✾
❋✐♥❛❧❧②✱ ✇❡ ❞❡r✐✈❡
nd
X
k=1
E
Y
g(k)h
′k−1,k+1mn≤ 64 k K k
2∞b
nX
|j|≥mn
α
1,∞( | j | )
≤ 64 k K k
2∞m
dnb
nX
|j|≥mn
| j |
dα
1,∞( | j | )
= o(1) ❜② ✭ 5 ✮ .
❆♣♣❧②✐♥❣ ❛❣❛✐♥ ❚❛②❧♦r✬s ❢♦r♠✉❧❛✱ ✐t r❡♠❛✐♥s t♦ ❝♦♥s✐❞❡r
Y
g(k)(h
′k−1,k+1− h
′k−1,k+1mn) = Y
g(k)(S
g(k−1)(Y ) − S
g(k)mn(Y ))h
′′k−1,k+1+ R
′k,
✇❤❡r❡ | R
′k| ≤ 2 | Y
g(k)(S
g(k−1)(Y ) − S
g(k)mn(Y ))(1 ∧ | S
g(k−1)(Y ) − S
g(k)mn(Y ) | ) |✳ ❉❡♥♦t✐♥❣
W
n= {− m
n+ 1, ..., m
n− 1 }
d❛♥❞ W
n∗= W
n\{ 0 }✱ ✐t ❢♦❧❧♦✇s t❤❛t
nd
X
k=1
E | R
′k| ≤ 2 E | ∆
0| X
i∈Wn
| ∆
i|
! 1 ∧ 1
n
d/2X
i∈Wn
| ∆
i|
!!
= 2 E
∆
20+ X
i∈Wn∗
| ∆
0∆
i|
1 ∧ 1 n
d/2X
i∈Wn
| ∆
i|
!
≤ 2 n
d/2X
i∈Wn
E (∆
20| ∆
i| ) + 2 X
i∈Wn∗
E | ∆
0∆
i|
≤ 8 k❑k
∞(n
db
n)
1/2X
i∈Wn
E ( | ∆
0∆
i| ) + 2 X
i∈Wn∗
E | ∆
0∆
i| s✐♥❝❡ ∆
0≤ 4 k K k
∞√ b
n❛✳s✳
= 8 E (∆
20) k❑k
∞(n
db
n)
1/2+ 2
1 + 4 k❑k
∞(n
db
n)
1/2X
i∈Wn∗
E ( | ∆
0∆
i| )
= O
1
(n
db
n)
1/2+ m
dnb
n1 + 1
(n
db
n)
1/2✭❜② ▲❡♠♠❛ 1✮
= o(1) ❜② ✭5✮.
❙♦✱ ✇❡ ❤❛✈❡ s❤♦✇♥ t❤❛t
n→+∞
lim
nd
X
k=1
E
Y
g(k)h
′k−1,k+1− Y
g(k)(S
g(k−1)− S
g(k)mn)h
′′k−1,k+1= 0.
■♥ ♦r❞❡r t♦ ♦❜t❛✐♥ ✭4✮ ✐t r❡♠❛✐♥s t♦ ❝♦♥tr♦❧
F
0= E
nd
X
k=1
h
′′k−1,k+1Y
g(k)22 + Y
g(k)S
g(k−1)(Y ) − S
g(k)mn(Y )
− η 2n
d!
.
✶✵
❲❡ ❝♦♥s✐❞❡r t❤❡ ❢♦❧❧♦✇✐♥❣ s❡ts✿
Λ
mnn= { i ∈ Λ
n; ρ( { i } , ∂Λ
n) ≥ m
n} ❛♥❞ I
nmn= { 1 ≤ i ≤ n
d; g(i) ∈ Λ
mnn} ,
❛♥❞ t❤❡ ❢✉♥❝t✐♦♥ Ψ ❢r♦♠ R
Zdt♦ R s✉❝❤ t❤❛t Ψ(∆) = ∆
20+ X
i∈V01∩Wn
2∆
0∆
i✇❤❡r❡ W
n= {− m
n+ 1, ..., m
n− 1 }
d.
❋♦r 1 ≤ k ≤ n
d✱ ✇❡ s❡t D
k(n)= η − Ψ ◦ T
g(k)(∆)✳ ❇② ❞❡✜♥✐t✐♦♥ ♦❢ Ψ ❛♥❞ ♦❢ t❤❡ s❡t I
nmn✱
✇❡ ❤❛✈❡ ❢♦r ❛♥② k ✐♥ I
nmnΨ ◦ T
g(k)(∆) = ∆
2g(k)+ 2∆
g(k)(S
g(k−1)(∆) − S
g(k)mn(∆)).
❚❤❡r❡❢♦r❡ ❢♦r k ✐♥ I
nmnD
k(n)n
d= η
n
d− Y
g(k)2− 2Y
g(k)(S
g(k−1)(Y ) − S
g(k)mn(Y )).
❙✐♥❝❡ lim
n→+∞n
−d| I
nmn| = 1 ✱ ✐t r❡♠❛✐♥s t♦ ❝♦♥s✐❞❡r
F
1= E
1 n
dnd
X
k=1
h
′′k−1,k+1D
(n)k
.
❆♣♣❧②✐♥❣ ▲❡♠♠❛ 1✱ ✇❡ ❤❛✈❡
F
1≤ E
1 n
dnd
X
k=1
h
′′k−1,k+1(∆
2g(k)− E (∆
20))
+ | η − E (∆
20) | + 2 X
j∈V01∩Wn
E | ∆
0∆
j|
≤ E
1 n
dnd
X
k=1
h
′′k−1,k+1(∆
2g(k)− E (∆
20))
+ o(1) + O(m
dnb
n),
✐t s✉✣❝❡s t♦ ♣r♦✈❡ t❤❛t
F
2= E
1 n
dnd
X
k=1
h
′′k−1,k+1(∆
2g(k)− E (∆
20))
❣♦❡s t♦ ③❡r♦ ❛s n ❣♦❡s t♦ ✐♥✜♥✐t②✳ ▲❡t M > 0 ❜❡ ✜①❡❞✳ ❲❡ ❤❛✈❡ F
2≤ F
2′+ F
2′′✇❤❡r❡
F
2′= E
1 n
dnd
X
k=1
h
′′k−1,k+1∆
2g(k)− E
M∆
2g(k)
✶✶
❛♥❞
F
2′′= E
1 n
dnd
X
k=1
h
′′k−1,k+1E
M∆
2g(k)− E (∆
20)
✇❤❡r❡ ✇❡ r❡❝❛❧❧ t❤❡ ♥♦t❛t✐♦♥ E
M∆
2g(k)= E
∆
2g(k)|F
Vg(k)M✳ ❚❤❡ ❢♦❧❧♦✇✐♥❣ r❡s✉❧t ✐s ❛
❙❡r✢✐♥❣ t②♣❡ ✐♥❡q✉❛❧✐t② ✇❤✐❝❤ ❝❛♥ ❜❡ ❢♦✉♥❞ ✐♥ ❬✶✼❪✳
▲❡♠♠❛ ✸ ▲❡t U ❛♥❞ V ❜❡ t✇♦ σ✲❛❧❣❡❜r❛s ❛♥❞ ❧❡t X ❜❡ ❛ r❛♥❞♦♠ ✈❛r✐❛❜❧❡ ♠❡❛s✉r❛❜❧❡
✇✐t❤ r❡s♣❡❝t t♦ U ✳ ■❢ 1 ≤ p ≤ r ≤ ∞ t❤❡♥
k E (X |V ) − E (X) k
p≤ 2(2
1/p+ 1) (α( U , V ))
1p−1rk X k
r.
❆♣♣❧②✐♥❣ ▲❡♠♠❛ 3 ❛♥❞ ❦❡❡♣✐♥❣ ✐♥ ♠✐♥❞ t❤❛t ∆
0✐s ❜♦✉♥❞❡❞ ❜② 4 k❑k
∞/ √
b
n✱ ✇❡ ❞❡r✐✈❡
F
2′′≤ k E
M∆
20− E (∆
20) k
1≤ 96 k❑k
2∞b
nα
1,∞(M )
■♥ t❤❡ ♦t❤❡r ♣❛rt✱
F
2′≤ 1 n
dnd
X
k=1
J
k1(M ) + J
k2(M)
✇❤❡r❡
J
k1(M ) = E
h
′′k−1,k+1M◦ T
−g(k)∆
20− E
M∆
20= 0 s✐♥❝❡ h
′′k−1,k+1M◦ T
−g(k)✐s F
V0M✲♠❡❛s✉r❛❜❧❡ ❛♥❞
J
k2(M ) = E
h
′′k−1,k+1◦ T
−g(k)− h
′′k−1,k+1M◦ T
−g(k)∆
20− E
M∆
20≤ E
2 ∧ X
|i|<M
| ∆
i| n
d/2
∆
20
≤ 4 k ❑ k
∞E (∆
20)
(n
db
n)
1/2+ 4 k ❑ k
∞(n
db
n)
1/2X
|i|<M i6=0
E | ∆
i∆
0| s✐♥❝❡ ∆
0≤ 4 k √ K k
∞b
n❛✳s✳
= O
1
(n
db
n)
1/2+ M
d√ b
nn
d/2✭❜② ▲❡♠♠❛ 1 ✮
❙♦✱ ♣✉tt✐♥❣ M = b
−1
n2d−1
❛♥❞ ❦❡❡♣✐♥❣ ✐♥ ♠✐♥❞ t❤❛t P
m≥0
m
2d−1α
1,∞(m) < + ∞✱ ✇❡
❞❡r✐✈❡
F
2= O M
2d−1α
1,∞(M ) + O
1 + b
d−1
n2d−1
(n
db
n)
1/2
= o(1).
❚❤❡ ♣r♦♦❢ ♦❢ ❚❤❡♦r❡♠ 1 ✐s ❝♦♠♣❧❡t❡✳
✶✷
✸ ❆♣♣❡♥❞✐①
Pr♦♦❢ ♦❢ ▲❡♠♠❛ 1 ✳ ❋♦r ❛♥② i ✐♥ Z
d❛♥❞ ❛♥② z ✐♥ R ✱ ✇❡ ♥♦t❡ ❑
i(z) = ❑
z−Xi
bn
✳ ❙♦✱ ✐❢
s ❛♥❞ t ❜❡❧♦♥❣s t♦ R ✱ ✇❡ ❤❛✈❡
E (Z
0(s)Z
0(t)) = 1 b
nE ( ❑
0(s) ❑
0(t)) − E ❑
0(s) E ❑
0(t)
❛♥❞
n→+∞
lim 1
b
nE (❑
0(s)❑
0(t)) = lim
n→+∞
Z
R
❑ (v) ❑
v + t − s b
nf (s − vb
n)dv = δ
stf(s) σ
2✇❤❡r❡ δ
st= 1 ✐❢ s = t ❛♥❞ δ
st= 0 ✐❢ s 6 = t✳ ❲❡ ❤❛✈❡ ❛❧s♦
n→+∞
lim 1 b
nE ❑
0(s) E ❑
0(t) = lim
n→+∞
b
nZ
R
❑ (v)f (s − vb
n)dv Z
R
❑ (w)f (t − wb
n)dw = 0.
❙♦✱ ✇❡ ♦❜t❛✐♥
E (∆
20) = λ
21E (Z
02(x)) + λ
22E (Z
02(y)) + 2λ
1λ
2E (Z
0(x)Z
0(y)) −−−−−→
n→+∞
η.
▲❡t i 6 = 0 ❜❡ ✜①❡❞ ✐♥ Z
d✳ ❲❡ ❤❛✈❡
E | ∆
0∆
i| ≤ λ
21E | Z
0(x)Z
i(x) | +λ
22E | Z
0(y)Z
i(y) | +λ
1λ
2E | Z
0(x)Z
i(y) | +λ
1λ
2E | Z
0(y)Z
i(x) | .
✭✼✮
❋♦r ❛♥② s ❛♥❞ t ✐♥ R ✱
E | Z
0(s)Z
i(t) | ≤ 1 b
nE
❑
0(s)❑
i(t) + 1
b
nE ❑
0(s)
E ❑
0(t)
.
▼♦r❡♦✈❡r✱ ✉s✐♥❣ ❆ss✉♠♣t✐♦♥s ✭❆✷✮ ❛♥❞ ✭❆✸✮✱ ✇❡ ❤❛✈❡
1 b
nE ❑
0(s)
E ❑
0(t)
= b
nZ
R
|❑ (u) | f (s − ub
n)du Z
R
|❑ (v) | f (t − vb
n)dv = O(b
n)
❛♥❞
1 b
nE
❑
0(s) ❑
i(t) = b
nZ Z
R2
❑ (w
1) ❑ (w
2)
f
0,i(s − w
1b
n, t − w
2b
n)dw
1dw
2= O(b
n).
❙♦✱ ✇❡ ♦❜t❛✐♥ ❢♦r ❛♥② s ❛♥❞ t ✐♥ R
E | Z
0(s)Z
i(t) | = O(b
n). ✭✽✮
❚❤❡ ♣r♦♦❢ ♦❢ ▲❡♠♠❛ 1 ✐s ❝♦♠♣❧❡t❡❞ ❜② ❝♦♠❜✐♥✐♥❣ ✭ 7 ✮ ❛♥❞ ✭ 8 ✮✳
✶✸
Pr♦♦❢ ♦❢ ▲❡♠♠❛ 2✳ ❲❡ ❢♦❧❧♦✇ t❤❡ ♣r♦♦❢ ❜② ❇♦sq✱ ▼❡r❧❡✈è❞❡ ❛♥❞ P❡❧✐❣r❛❞ ✭❬✸❪✱ ♣❛❣❡s
✽✽✲✽✾✮✳ ❋✐rst✱ m
dn❣♦❡s t♦ ✐♥✜♥✐t② s✐♥❝❡ b
n❣♦❡s t♦ ③❡r♦ ❛♥❞ m
n≥ h b
−n2d1i ✳ ❋♦r ❛♥②
♣♦s✐t✐✈❡ ✐♥t❡❣❡r m ✱ ✇❡ ❝♦♥s✐❞❡r
ψ(m) = X
|i|>m
| i |
dα
1,∞( | i | ).
❙✐♥❝❡ t❤❡ ♠✐①✐♥❣ ❝♦♥❞✐t✐♦♥ ✭ 1 ✮ ✐s ❡q✉✐✈❛❧❡♥t t♦ P
k∈Zd
| k |
dα
1,∞( | k | ) < ∞✱ ✇❡ ❦♥♦✇ t❤❛t ψ(m) ❝♦♥✈❡r❣❡s t♦ ③❡r♦ ❛s m ❣♦❡s t♦ ✐♥✜♥✐t②✳ ▼♦r❡♦✈❡r✱ ✇❡ ❤❛✈❡
m
dnb
n≤ max (
p b
n, C
dr ψ h
b
−n2d1i + 2
db
n!)
−−−−−→
n→+∞
0
✇❤❡r❡ C
d✐s s♦♠❡ ♣♦s✐t✐✈❡ ❝♦♥st❛♥t ❞❡♣❡♥❞✐♥❣ ♦♥ t❤❡ ❞✐♠❡♥s✐♦♥ d ✳ ❲❡ ❤❛✈❡ ❛❧s♦
m
dn≥ 1 b
nr ψ h
b
−n2d1i ≥ 1 b
np ψ (m
n) s✐♥❝❡ h b
−n2d1i ≤ m
n.
❋✐♥❛❧❧②✱ ✇❡ ♦❜t❛✐♥
1 m
dnb
nX
|i|>mn
| i |
dα
1,∞( | i | ) ≤ p
ψ(m
n) −−−−−→
n→+∞