Supporting Technical Report for the Article "Variational Bayesian Inference for Source Separation and Robust Feature Extraction"

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https://hal.inria.fr/hal-00687162v3

Submitted on 25 Feb 2014

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Supporting Technical Report for the Article ”Variational Bayesian Inference for Source Separation and Robust

Feature Extraction”

Kamil Adiloglu, Emmanuel Vincent

To cite this version:

Kamil Adiloglu, Emmanuel Vincent. Supporting Technical Report for the Article ”Variational

Bayesian Inference for Source Separation and Robust Feature Extraction”. [Technical Report] RT-

0423, INRIA. 2014, pp.26. �hal-00687162v3�

0249-0803 ISRN INRIA/R T--423--FR+ENG

TECHNICAL REPORT N° 423

February 2014

Supporting Technical Report for the Article

“Variational Bayesian Inference for Source

Separation and Robust Feature Extraction”

Kamil Adilo˘glu, Emmanuel Vincent

RESEARCH CENTRE

RENNES – BRETAGNE ATLANTIQUE

❙✉♣♣♦rt✐♥❣ ❚❡❝❤♥✐❝❛❧ ❘❡♣♦rt ❢♦r t❤❡ ❆rt✐❝❧❡

✏❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s✐❛♥ ■♥❢❡r❡♥❝❡ ❢♦r ❙♦✉r❝❡

❙❡♣❛r❛t✐♦♥ ❛♥❞ ❘♦❜✉st ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥✑

❑❛♠✐❧ ❆❞✐❧♦➜❧✉✱ ❊♠♠❛♥✉❡❧ ❱✐♥❝❡♥t

Pr♦❥❡❝t✲❚❡❛♠ ▼❡t✐ss

❚❡❝❤♥✐❝❛❧ ❘❡♣♦rt ♥➦ ✹✷✸ ✖ ❋❡❜r✉❛r② ✷✵✶✹ ✖ ✷✸ ♣❛❣❡s

❆❜str❛❝t✿ ❚❤✐s t❡❝❤♥✐❝❛❧ r❡♣♦rt ♣r❡s❡♥ts t❤❡ ❞❡t❛✐❧s ♦❢ t❤❡ ❞❡r✐✈❛t✐♦♥ ♦❢ t❤❡ ✈❛r✐❛t✐♦♥❛❧ ❇❛②❡s✐❛♥

s♦✉r❝❡ s❡♣❛r❛t✐♦♥ ❛❧❣♦r✐t❤♠ ✐♥ ❬✶❪✳ ❋♦r t❤❡ ♠♦t✐✈❛t✐♦♥ ❜❡❤✐♥❞ t❤✐s ❛❧❣♦r✐t❤♠ ❛♥❞ ❢♦r ❡①♣❡r✐♠❡♥t❛❧

r❡s✉❧ts✱ s❡❡ ❬✶❪✳

❑❡②✲✇♦r❞s✿ ❆✉❞✐♦ s♦✉r❝❡ s❡♣❛r❛t✐♦♥✱ ❧♦❝❛❧ ●❛✉ss✐❛♥ ♠♦❞❡❧✐♥❣✱ ♥♦♥✲♥❡❣❛t✐✈❡ ♠❛tr✐① ❢❛❝t♦r✐③❛✲

t✐♦♥✱ ✈❛r✐❛t✐♦♥❛❧ ❇❛②❡s✐❛♥ ✐♥❢❡r❡♥❝❡

❚❤✐s ✇♦r❦ ✐s ❛ ♣❛rt ♦❢ t❤❡ ◗❯❆❊❘❖ ♣r♦❥❡❝t ❢✉♥❞❡❞ ❜② ❖❙❊❖✳

❘❛♣♣♦rt ❚❡❝❤♥✐q✉❡ ♣♦✉r ❧✬❆rt✐❝❧❡ ✏❱❛r✐❛t✐♦♥❛❧

❇❛②❡s✐❛♥ ■♥❢❡r❡♥❝❡ ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞

❘♦❜✉st ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥✑

❘és✉♠é ✿ ❈❡ r❛♣♣♦rt ♣rés❡♥t❡ ❧❡s ❞ét❛✐❧s ❞❡ ❝♦♥❝❡♣t✐♦♥ ❞❡ ❧✬❛❧❣♦r✐t❤♠❡ ✈❛r✐✲

❛t✐♦♥❡❧ ❜❛②❡s✐❡♥ ♣♦✉r ❧❛ sé♣❛r❛t✐♦♥ ❞❡ s♦✉r❝❡s ❞❛♥s ❬✶❪✳ ▲❛ ♠♦t✐✈❛t✐♦♥ s♦✉s✲

❥❛❝❡♥t❡ á ❝❡t ❛❧❣♦r✐t❤♠❡ ❡t ❧❡s rés✉❧t❛ts s♦♥t ❞♦♥♥és ❞❛♥s ❬✶❪✳

▼♦ts✲❝❧és ✿ ❙é♣❛r❛t✐♦♥ ❞❡ s♦✉r❝❡s ❛✉❞✐♦✱ ♠♦❞è❧❡ ❣❛✉ss✐❡♥ ❧♦❝❛❧✱ ❢❛❝t♦r✐s❛t✐♦♥

♠❛tr✐❝✐❡❧❧❡ ♣♦s✐t✐✈❡✱ ✐♥❢ér❡♥❝❡ ✈❛r✐❛t✐♦♥❡❧❧❡ ❜❛②és✐❡♥♥❡

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞ ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥ ✸

❈♦♥t❡♥ts

✶ ▼♦❞❡❧ ✹

✶✳✶ ❙♣❛t✐❛❧ ▼♦❞❡❧ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✹

✶✳✷ ◆♦♥♥❡❣❛t✐✈❡ ❚❡♥s♦r ❋❛❝t♦r✐③❛t✐♦♥ ❛s ❛ ❙♣❡❝tr❛❧ ▼♦❞❡❧ ✳ ✳ ✳ ✳ ✳ ✳ ✺

✶✳✸ Pr✐♦r ❉✐str✐❜✉t✐♦♥s ❢♦r t❤❡ P❛r❛♠❡t❡rs ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✻

✶✳✹ ❏♦✐♥t ❉✐str✐❜✉t✐♦♥ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✻

✷ ❱❛r✐❛t✐♦♥❛❧ ■♥❢❡r❡♥❝❡ ✽

✷✳✶ ●❡♥❡r❛❧ ❆♣♣r♦❛❝❤ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✽

✷✳✷ ❆♣♣❧✐❝❛t✐♦♥ t♦ t❤❡ Pr♦♣♦s❡❞ ▼♦❞❡❧ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✶✵

✷✳✷✳✶ ❆✉①✐❧✐❛r② ❱❛r✐❛❜❧❡s ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✶✶

✷✳✷✳✷ ❚✐❣❤t❡♥✐♥❣ t❤❡ ❇♦✉♥❞ ✇rt✳ t❤❡ ❆✉①✐❧✐❛r② ❱❛r✐❛❜❧❡s ✳ ✳ ✳ ✳ ✶✷

✷✳✷✳✸ ❱❛r✐❛t✐♦♥❛❧ ❯♣❞❛t❡s ❢♦r t❤❡ ◆❚❋ P❛r❛♠❡t❡rs ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✶✸

✷✳✷✳✹ ❱❛r✐❛t✐♦♥❛❧ ❯♣❞❛t❡s ❢♦r t❤❡ ❙♦✉r❝❡ ❈♦♠♣♦♥❡♥ts ✳ ✳ ✳ ✳ ✳ ✶✼

✷✳✷✳✺ ❱❛r✐❛t✐♦♥❛❧ ❯♣❞❛t❡s ❢♦r t❤❡ ▼✐①✐♥❣ P❛r❛♠❡t❡rs ✳ ✳ ✳ ✳ ✳ ✳ ✶✽

✷✳✸ ▲♦✇❡r ❇♦✉♥❞ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✶✾

✷✳✹ ❙✉♠♠❛r② ♦❢ t❤❡ ❆❧❣♦r✐t❤♠ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✳ ✷✷

✹ ❆❞✐❧♦➜✉ ✫ ❱✐♥❝❡♥t

✶ ▼♦❞❡❧

✶✳✶ ❙♣❛t✐❛❧ ▼♦❞❡❧

❲❡ ❛❞♦♣t t❤❡ ♠♦❞❡❧ ♣r♦♣♦s❡❞ ✐♥ ❬✺❪✳ ❚❤✐s ♠♦❞❡❧ ♦♣❡r❛t❡s ✐♥ t❤❡ ❙❚❋❚ ❞♦♠❛✐♥✳

❚❤❡ ♠✐①✐♥❣ ❡q✉❛t✐♦♥ ✐♥ t✐♠❡ ❢r❡q✉❡♥❝② ❜✐♥ (n, f) ❝❛♥ ❜❡ ❢♦r♠✉❧❛t❡❞ ❜② ✉s✐♥❣

t❤❡ s♦✉r❝❡ ✐♠❛❣❡s y _{j,f n} ❛s ❢♦❧❧♦✇s✿

x _{f n} = X J

j=1

y _{j,f n} + ǫ _{f n} . ✭✶✮

■♥ t❤✐s ❞♦♠❛✐♥✱ x _{f n} r❡♣r❡s❡♥ts t❤❡ I × 1 ✈❡❝t♦r ❝♦♥t❛✐♥✐♥❣ t❤❡ ♠✐①t✉r❡ ❙❚❋❚

❝♦❡✣❝✐❡♥ts ✐♥ t✐♠❡✲❢r❡q✉❡♥❝② ❜✐♥ (n, f)✱ ✱ ✇❤❡r❡ I ✐s t❤❡ ♥✉♠❜❡r ♦❢ ❝❤❛♥♥❡❧s✳

y _{j,f n} r❡♣r❡s❡♥ts t❤❡ I × 1 ✈❡❝t♦r ❝♦♥s✐st✐♥❣ ♦❢ t❤❡ s♣❛t✐❛❧ ✐♠❛❣❡ ♦❢ s♦✉r❝❡ j ♦♥

❛❧❧ ♠✐①t✉r❡ ❝❤❛♥♥❡❧s ✐♥ t❤❡ s❛♠❡ t✐♠❡✲❢r❡q✉❡♥❝② ❜✐♥✳ ❋✐♥❛❧❧② ǫ f n ✐s t❤❡ ♥♦✐s❡

✐♥ t❤❡ ❙❚❋❚ ❞♦♠❛✐♥✳ ❲❡ ❛ss✉♠❡ t❤❛t ❡❛❝❤ s♦✉r❝❡ ✐♠❛❣❡ ❢♦❧❧♦✇s ❛ ③❡r♦✲♠❡❛♥

❝♦♠♣❧❡①✲✈❛❧✉❡❞ ●❛✉ss✐❛♥ ❞✐str✐❜✉t✐♦♥

y _{j,f n} ∼ N (0, v j,f n R _j,f ), ✭✷✮

✇❤❡r❡ R _j,f ✐s ❛♥ I × I ♠❛tr✐① ♦❢ r❛♥❦ R j ✇❤✐❝❤ ✐s ❝❛❧❧❡❞ t❤❡ s♣❛t✐❛❧ ❝♦✈❛r✐❛♥❝❡

♠❛tr✐① ❛♥❞ r❡♣r❡s❡♥ts t❤❡ s♣❛t✐❛❧ ❝❤❛r❛❝t❡r✐st❝s ♦❢ s♦✉r❝❡ j ❛♥❞ ♦❢ t❤❡ ♠✐①✲

✐♥❣ s②st❡♠✱ ❛♥❞ v j,f n ✐s ❛ s❝❛❧❛r s♣❡❝tr❛❧ ♣♦✇❡r ✇❤✐❝❤ r❡♣r❡s❡♥ts t❤❡ s♣❡❝tr❛❧

❝❤❛r❛❝t❡r✐st✐❝s ♦❢ s♦✉r❝❡ j✳

❚❤✐s ♠♦❞❡❧ ❝❛♥ ❛❧t❡r♥❛t✐✈❡❧② ❜❡ r❡♣r❡s❡♥t❡❞ ❛s ❢♦❧❧♦✇s ❬✺❪✳ R _j,f ❝❛♥ ❜❡

✇r✐tt❡♥ ❛s R _j,f = A _j,f A ^H _j,f ✱ ✇❤❡r❡ A _j,f ✐s ❛ I × R j ❞✐♠❡♥s✐♦♥❛❧ ❝♦♠♣❧❡①✲✈❛❧✉❡❞

♠✐①✐♥❣ ♠❛tr✐① ♦❢ r❛♥❦ R j ❢♦r s♦✉r❝❡ j✳ ❋♦r ❡❛❝❤ s♦✉r❝❡ j✱ ✇❡ ❞❡✜♥❡ R j s♦✉r❝❡

❝♦♠♣♦♥❡♥ts s jr,f n ❞✐str✐❜✉t❡❞ ❛s

s jr,f n ∼ N (0, v j,f n ). ✭✸✮

❉❡♥♦t✐♥❣ ❜② R = P J

j=1 R j t❤❡ t♦t❛❧ ♥✉♠❜❡r ♦❢ s♦✉r❝❡ ❝♦♠♣♦♥❡♥ts✱ t❤❡

s♦✉r❝❡ ❝♦❡✣❝✐❡♥ts ❝❛♥ ❜❡ ❢♦r♠✉❧❛t❡❞ ❛s

s _{f n} = [s ^T _{1,f n} , . . . , s ^T _{j,f n} , . . . , s ^T _{J,f n} ] ^T , ✭✹✮

✇❤❡r❡ s _{f n} ✐s ❛♥ R × 1 ✈❡❝t♦r ♦❢ s♦✉r❝❡ ❝♦❡✣❝✐❡♥ts ✇✐t❤

s _{j,f n} = [s j1,f n , . . . , s jr,f n , . . . , s jR

j

,f n ] ^T . ✭✺✮

❍❡♥❝❡✱ t❤❡ ♣r✐♦r ❞✐str✐❜✉t✐♦♥ ♦❢ t❤❡ s♦✉r❝❡s ✐♥ t✐♠❡✲❢r❡q✉❡♥❝② ❜✐♥ (f, n) ✐s

❣✐✈❡♥ ❜②

s _{f n} = N (0, Σ _{s,f n} ), ✭✻✮

✇❤❡r❡ Σ _{s,f n} ✐s ❛♥ R × R ❞✐❛❣♦♥❛❧ ❝♦✈❛r✐❛♥❝❡ ♠❛tr✐① ❝♦♥s✐st✐♥❣ ♦❢ v j,f n r❡♣❡❛t❡❞

R j t✐♠❡s ❢♦r ❡❛❝❤ s♦✉r❝❡ ❝♦♠♣♦♥❡♥t s jr,f n ♦❢ s♦✉r❝❡ j✳ ❋✐♥❛❧❧②✱ t❤❡ ♠✐①✐♥❣

❡q✉❛t✐♦♥ ✉s✐♥❣ t❤❡ s♦✉r❝❡ ❝♦♠♣♦♥❡♥ts ✐♥st❡❛❞ ♦❢ t❤❡ s♦✉r❝❡ s♣❛t✐❛❧ ✐♠❛❣❡s ❛s ✐♥

✭✶✮ ✐s ❣✐✈❡♥ ❜②

x _{f n} = A _f s _{f n} + ǫ _{f n} . ✭✼✮

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞ ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥ ✺

❲❡ ❛ss✉♠❡ t❤❛t t❤❡ ♠✐①✐♥❣ s②st❡♠ A ✐s st❛t✐♦♥❛r②✳ ❙♦✱ t❤❡ ♠✐①✐♥❣ s②st❡♠ ✐s

❡①♣r❡ss❡❞ ❛s

A _f = [ A _1,f , . . . , A _j,f , . . . , A _J,f ]. ✭✽✮

❋✐♥❛❧❧②✱ ✇❡ ❛ss✉♠❡ ❛ ●❛✉ss✐❛♥ ③❡r♦ ♠❡❛♥ ♥♦✐s❡ ✇✐t❤ ❛ ❝♦♥st❛♥t ♥♦✐s❡ ✈❛r✐❛♥❝❡

ǫ f n ∼ N (0, Σ _b )✱ ✇❤❡r❡ Σ _b = σ ² _b I ✳ ❚❤✐s ❣✐✈❡s ✉s t❤❡ ♣♦ss✐❜✐❧✐t② t♦ ❢♦r♠✉❧❛t❡ t❤❡

❧✐❦❡❧✐❤♦♦❞ ♦❢ t❤❡ ♠✐①t✉r❡ ❝♦❡✣❝✐❡♥ts ❛s ❢♦❧❧♦✇s✿

p(X | S, A) = Y N

n=1

Y F

f=1

N (x f n | A _f s _{f n} , σ ² _b I), ✭✾✮

✇❤❡r❡ X = { x _{f n} } ^{n=1···N,f =1···F} ❛♥❞ S = { s _{f n} } ^{n=1···N,f =1···F} ✳

✶✳✷ ◆♦♥♥❡❣❛t✐✈❡ ❚❡♥s♦r ❋❛❝t♦r✐③❛t✐♦♥ ❛s ❛ ❙♣❡❝tr❛❧ ▼♦❞❡❧

❲❡ ❛ss✉♠❡ ❛ t❤r❡❡✲❧❡✈❡❧ ❞❡❝♦♠♣♦s✐t✐♦♥ ♦❢ t❤❡ s♦✉r❝❡ ✈❛r✐❛♥❝❡s v j,f n ✐♥ ❛ ♥♦♥✲

♥❡❣❛t✐✈❡ t❡♥s♦r ❢❛❝t♦r✐③❛t✐♦♥ ✭◆❚❋✮ ❢❛s❤✐♦♥ ❬✺❪✳ ■♥ t❤❡ ✜rst ❧❡✈❡❧ ✇❡ ❛ss✉♠❡ t❤❛t t❤❡ ✈❛r✐❛♥❝❡s ❛r❡ t❤❡ ♣r♦❞✉❝t ♦❢ ❛♥ ❡①❝✐t❛t✐♦♥ ❛♥❞ ❛ ✜❧t❡r

v j,f n = v _{j,f n} ^ex v _{j,f n} ^ft . ✭✶✵✮

❆t t❤❡ s❡❝♦♥❞ ❧❡✈❡❧✱ t❤❡ ❡①❝✐t❛t✐♦♥ s♣❡❝tr❛❧ ♣♦✇❡r v _{j,f n} ^ex ✐s ❡①♣r❡ss❡❞ ❛s t❤❡

s✉♠ ♦❢ ❜❛s✐s s♣❡❝tr❛ s❝❛❧❡❞ ❜② t✐♠❡ ❛❝t✐✈❛t✐♦♥ ❝♦❡✣❝✐❡♥ts✳ ❋✐♥❛❧❧②✱ ❛t t❤❡ t❤✐r❞

❧❡✈❡❧✱ t❤❡ ❜❛s✐s s♣❡❝tr❛ ❛r❡ ❞❡✜♥❡❞ ❛s t❤❡ s✉♠ ♦❢ ♥❛rr♦✇❜❛♥❞ s♣❡❝tr❛❧ ♣❛tt❡r♥s w ^ex _{j,f l} ✇❡✐❣❤t❡❞ ❜② s♣❡❝tr❛❧ ❡♥✈❡❧♦♣❡ ❝♦❡✣❝✐❡♥ts u ^ex _j,lk ✳ ❙✐♠✐❧❛r❧②✱ t❤❡ t✐♠❡ ❛❝t✐✈❛✲

t✐♦♥ ❝♦❡✣❝✐❡♥ts ❛r❡ r❡♣r❡s❡♥t❡❞ ❛s t❤❡ s✉♠ ♦❢ t✐♠❡✲❧♦❝❛❧✐③❡❞ ♣❛tt❡r♥s h ^ex _j,mn

✇❡✐❣❤t❡❞ ❜② t❡♠♣♦r❛❧ ❡♥✈❡❧♦♣❡ ❝♦❡✣❝✐❡♥ts g _j,km ^ex ✳ ❚❤❡ s❛♠❡ ❞❡❝♦♠♣♦s✐t✐♦♥

❛♣♣❧✐❡s t♦ t❤❡ ✜❧t❡r s♣❡❝tr❛❧ ♣♦✇❡r v _{j,f n} ^ft ✳ ❖✈❡r❛❧❧✱ t❤❡ ❝♦♠♣❧❡t❡ ❢❛❝t♦r✐③❛t✐♦♥

s❝❤❡♠❡ ✐s ❛s ❢♦❧❧♦✇s✿

v _{j,f n} ^ex =

K

_j^ex

X

k=1 M

_j^ex

X

m=1 L

^ex_j

X

l=1

h ^ex _j,mn g _j,km ^ex u ^ex _j,lk w _{j,f l} ^ex , ✭✶✶✮

v _{j,f n} ^ft =

K

_j^ft

X

k

^′

=1 M

_j^ft

X

m

^′

=1 L

^ft_j

X

l

^′

=1

h ^ft _j,m

′

n g ^ft _j,k

′

m

^′

u ^ft _j,l

′

k

^′

w _{j,f l} ^ft

′

. ✭✶✷✮

❚❤✐s ❢r❛♠❡✇♦r❦ ♠❛❦❡s ✐t ♣♦ss✐❜❧❡ t♦ ❡①♣❧♦✐t ❛ ✇✐❞❡ r❛♥❣❡ ♦❢ ♣r✐♦r ✐♥❢♦r♠❛t✐♦♥

❛❜♦✉t t❤❡ s♦✉r❝❡s✳ ❋♦r ✐♥st❛♥❝❡✱ ❤❛r♠♦♥✐❝✐t② ❝❛♥ ❜❡ ❡♥❢♦r❝❡❞ ❜② ✜①✐♥❣ w ^ex _{j,f l} ❛s

♥❛rr♦✇❜❛♥❞ ❤❛r♠♦♥✐❝ s♣❡❝tr❛ ❛♥❞ ❧❡tt✐♥❣ t❤❡ s♣❡❝tr❛❧ ❡♥✈❡❧♦♣❡ ❛♥❞ t❤❡ ❛❝t✐✈❡

♣✐t❝❤❡s ❜❡ ✐♥❢❡rr❡❞ ❢r♦♠ t❤❡ ❞❛t❛ ✈✐❛ u ^ex _j,lk ❛♥❞ g _j,km ^ex ✱ r❡s♣❡❝t✐✈❡❧② ❬✺❪✳ ❋♦r ♠♦r❡

❞❡t❛✐❧s ❛♥❞ ❡①❛♠♣❧❡s ♦❢ ♣♦ss✐❜❧❡ s♣❡❝tr❛❧ ❛♥❞ t❡♠♣♦r❛❧ ❝♦♥str❛✐♥ts✱ s❡❡ ❬✺❪✳

❚❤✐s t❤r❡❡✲❧❡✈❡❧ ◆❚❋ ❞❡❝♦♠♣♦s✐t✐♦♥ ❝❛♥ ❜❡ s❤♦✇♥ ✐♥ ♠❛tr✐① ❢♦r♠ ❛s ❢♦❧❧♦✇s V _j = (W ^ex _j U ^ex _j G ^ex _j H ^ex _j ) ⊙ (W _j ^ft U ^ft _j G ^ft _j H ^ft _j ), ✭✶✸✮

✇❤❡r❡ ⊙ ♠❡❛♥s ❡❧❡♠❡♥t✲✇✐s❡ ♠❛tr✐① ♠✉❧t✐♣❧✐❝❛t✐♦♥✳

✻ ❆❞✐❧♦➜✉ ✫ ❱✐♥❝❡♥t

✶✳✸ Pr✐♦r ❉✐str✐❜✉t✐♦♥s ❢♦r t❤❡ P❛r❛♠❡t❡rs

❊❛❝❤ ♣❛r❛♠❡t❡r ♠❛② ❜❡ ✜①❡❞ ♦r ❛❞❛♣t❡❞ t♦ t❤❡ ❞❛t❛✳ ■♥ ❛ ❢✉❧❧② ❇❛②❡s✐❛♥

tr❡❛t♠❡♥t✱ ✇❡ ♥❡❡❞ t♦ ❞❡✜♥❡ t❤❡ ♣r✐♦r ❞✐str✐❜✉t✐♦♥s ❢♦r t❤♦s❡ ♣❛r❛♠❡t❡rs ✇❤✐❝❤

❛r❡ ❛❞❛♣t❡❞ t♦ t❤❡ ❞❛t❛✳ ❲❡ ❛ss✉♠❡ t❤❡ ◆❚❋ ♣❛r❛♠❡t❡rs ♦❢ t❤❡ s♦✉r❝❡ ✈❛r✐❛♥❝❡s

❢♦❧❧♦✇ t❤❡ ♥♦♥✲✐♥❢♦r♠❛t✐✈❡ ❏❡✛r❡②s ♣r✐♦r J (x) ∝ ¹ _x

w ^ex _{j,f l} ∼ J , ✭✶✹✮

u ^ex _j,lk ∼ J , ✭✶✺✮

g ^ex _j,km ∼ J , ✭✶✻✮

h ^ex _j,mn ∼ J , ✭✶✼✮

w ^ft _{j,f l}

′

∼ J , ✭✶✽✮

u ^ft _j,l

′

k

^′

∼ J , ✭✶✾✮

g ^ft _j,k

′

m

^′

∼ J , ✭✷✵✮

h ^ft _j,m

′

n ∼ J . ✭✷✶✮

❋♦r t❤❡ ♠✐①✐♥❣ s②st❡♠✱ ✇❡ t❛❦❡ t❤❡ ❞❡♣❡♥❞❡♥❝✐❡s ❜❡t✇❡❡♥ t❤❡ ❝❤❛♥♥❡❧s ❛♥❞

❜❡t✇❡❡♥ t❤❡ s♦✉r❝❡ ❝♦♠♣♦♥❡♥ts ✐♥t♦ ❛❝❝♦✉♥t✳ ❚❤❡r❡❢♦r❡✱ ✇❡ ❝♦♥s✐❞❡r t❤❡ ♠✐①✐♥❣

♠❛tr✐① A _f ❛s ❛ ✇❤♦❧❡ ❛♥❞ ❞❡✜♥❡ t❤❡ ♣r✐♦r ❞✐str✐❜✉t✐♦♥ ❛❝❝♦r❞✐♥❣❧②✳ ❋✐rst✱ ✇❡

r❡s❤❛♣❡ t❤❡ ♠✐①✐♥❣ ♠❛tr✐① A _f ✐♥t♦ ❛ ✈❡❝t♦r A _f ✳ ❋♦r t❤✐s✱ ✇❡ ❝♦♥❝❛t❡♥❛t❡

t❤❡ r♦✇ ✈❡❝t♦rs ♦❢ A _f ✐♥t♦ t❤❡ ❝♦❧✉♠♥ ✈❡❝t♦r A _f ✳ ❚❤❡♥✱ ✇❡ ❞❡✜♥❡ t❤❡ ♣r✐♦r

❞✐str✐❜✉t✐♦♥ ♦❢ A _f t♦ ❜❡ ❛ ❝♦♠♣❧❡① ♠✉❧t✐✈❛r✐❛t❡ ●❛✉ss✐❛♥ ❞✐str✐❜✉t✐♦♥ ❛s ❢♦❧❧♦✇s

A _f ∼ N (µ A,f , Σ _A,f ). ✭✷✷✮

■♥ t❤❡ ❢♦❧❧♦✇✐♥❣✱ ✇❡ ❛ss✉♠❡ t❤❛t Σ _A,f → + ∞ s♦ t❤❛t t❤✐s ♣r✐♦r ✐s ❛❝t✉❛❧❧②

✢❛t✳

✶✳✹ ❏♦✐♥t ❉✐str✐❜✉t✐♦♥

❲✐t❤ t❤✐s ♣r✐♦r ✐♥❢♦r♠❛t✐♦♥ ❛ss✉♠❡❞✱ ✇❡ ❝❛♥ ❢♦r♠✉❧❛t❡ t❤❡ ❥♦✐♥t ❞✐str✐❜✉t✐♦♥

p(X, Z)✱ ✇❤❡r❡ Z ✐s t❤❡ s❡t ♦❢ ❛❧❧ ♠♦❞❡❧ ♣❛r❛♠❡t❡rs

Z = { S, A, W ^ex , U ^ex , G ^ex , H ^ex , W ^ft , U ^ft , G ^ft , H ^ft } . ✭✷✸✮

❛s

p( X , Z ) = p( X | S , A )p( S | W ^ex , U ^ex , G ^ex , H ^ex , W ^ft , U ^ft , G ^ft , H ^ft )p( A ) p(W ^ex )p(U ^ex )p(G ^ex )p(H ^ex )p(W ^ft )p(U ^ft )p(G ^ft )p(H ^ft ). ✭✷✹✮

❚❤❡ log✲❞✐str✐❜✉t✐♦♥ ✐s t❤❡♥ ❣✐✈❡♥ ❜②

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞ ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥ ✼

log p( X , Z ) = log p( X | S , A ) + log p( S | W

^ex

, U

^ex

, G

^ex

, H

^ex

, W

^ft

, U

^ft

, G

^ft

, H

^ft

) + log p( A ) + log p( W

^ex

) + log p( U

^ex

) + log p( G

^ex

) + log p( H

^ex

) + log p( W

^ft

) + log p( U

^ft

) + log p( G

^ft

) + log p( H

^ft

),

= X

f,n

log N ( x

_{f n}

| A

_f

s

_{f n}

, σ

b²

I )

+ X

f,n

log N ( s

_{f n}

|0, Σ

s,f n

)

+ X

j,f,l

log J (w

^ex_{j,f l}

)

+ X

j,l,k

log J (u

^exj,lk

)

+ X

j,k,m

log J (g

j,km^ex

)

+ X

j,m,n

log J (h

^exj,mn

)

+ X

j,f,l′

log J (w

^ftj,f l′

)

+ X

j,l^′,k^′

log J (u

^ftj,l^′k^′

)

+ X

j,k′,m′

log J (g

_j,k^ft′m^′

)

+ X

j,m′,n

log J (h

^ftj,m′n

)

+ X

f

log N ( A

f

|µ

^A,f

, Σ

A,f

). ✭✷✺✮

✽ ❆❞✐❧♦➜✉ ✫ ❱✐♥❝❡♥t

✷ ❱❛r✐❛t✐♦♥❛❧ ■♥❢❡r❡♥❝❡

❲❡ ❛✐♠ t♦ ♦❜t❛✐♥ t❤❡ ♣♦st❡r✐♦r ❞✐str✐❜✉t✐♦♥ ♦❢ t❤❡ ♠♦❞❡❧ ♣❛r❛♠❡t❡rs p( Z | X )✳

❍♦✇❡✈❡r ❡①❛❝t ❇❛②❡s✐❛♥ ✐♥❢❡r❡♥❝❡ ✐s ✐♥tr❛❝t❛❜❧❡✳ ❚❤❡r❡❢♦r❡ ✇❡ r❡s♦rt t♦ ❛ ✈❛r✐✲

❛t✐♦♥❛❧ ❇❛②❡s✐❛♥ ❛♣♣r♦①✐♠❛t✐♦♥ ❬✷❪✳

✷✳✶ ●❡♥❡r❛❧ ❆♣♣r♦❛❝❤

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s✐❛♥ ✐♥❢❡r❡♥❝❡ ❛✐♠s t♦ ♦❜t❛✐♥ ❛♥ ❛♣♣r♦①✐♠❛t✐♦♥ q(Z) ♦❢ t❤❡

tr✉❡ ♣♦st❡r✐♦r ❞✐str✐❜✉t✐♦♥ p(Z | X) t❤❛t ♠✐♥✐♠✐③❡s t❤❡ ❑✉❧❧❜❛❝❦✲▲❡✐❜❧❡r ✭❑▲✮

❞✐✈❡r❣❡♥❝❡

KL(q || p) = − Z

q(Z) log p(Z | X)

q(Z) dZ. ✭✷✻✮

▼❛r❣✐♥❛❧✐③✐♥❣ ♦✉t t❤❡ ♠♦❞❡❧ ♣❛r❛♠❡t❡rs Z ❢r♦♠ ✭✷✹✮ ❣✐✈❡s t❤❡ ♠❛r❣✐♥❛❧

❧✐❦❡❧✐❤♦♦❞ p(X) ♦r ❡✈✐❞❡♥❝❡✳ ❲❡ ❝❛♥ s❤♦✇ t❤❛t t❤❡ ❢♦❧❧♦✇✐♥❣ ❡q✉❛t✐♦♥ ❤♦❧❞s log p(X) = L (q) + KL(q || p), ✭✷✼✮

✇❤❡r❡ t❤❡ ❢r❡❡ ❡♥❡r❣② L (q) ✐s ❣✐✈❡♥ ❜②

L (q) = Z

q(Z) log p( X , Z )

q(Z) dZ, ✭✷✽✮

✭✷✾✮

■♥ t❤✐s ❢♦r♠✉❧❛t✐♦♥✱ q(Z) ✐s t❤❡ ❥♦✐♥t ❞✐str✐❜✉t✐♦♥ ♦❢ t❤❡ ♠♦❞❡❧ ♣❛r❛♠❡t❡rs

✇❤✐❝❤ ✇❡ ✉s❡ t♦ ❛♣♣r♦①✐♠❛t❡ t❤❡ tr✉❡ ♣♦st❡r✐♦r ❞✐str✐❜✉t✐♦♥ p(Z | X)✳ L (q)

✐s ❝❛❧❧❡❞ t❤❡ ❢r❡❡ ❡♥❡r❣② ❛♥❞ ✐t ✐s ❛ ❧♦✇❡r ❜♦✉♥❞ ♦❢ t❤❡ ♠❛r❣✐♥❛❧ ❧✐❦❡❧✐❤♦♦❞✳

▼❛①✐♠✐③✐♥❣ t❤✐s ❢r❡❡ ❡♥❡r❣② ✇rt✳ q( Z ) ♠✐♥✐♠✐③❡s t❤❡ ❑▲✲❞✐✈❡r❣❡♥❝❡ ❜❡t✇❡❡♥

t❤❡ ❛♣♣r♦①✐♠❛t✐♥❣ ❞✐str✐❜✉t✐♦♥ q( Z ) ❛♥❞ t❤❡ tr✉❡ ♣♦st❡r✐♦r ❬✷❪✳ ◆♦t❡ t❤❛t t❤❡

❑▲✲❞✐✈❡r❣❡♥❝❡ ✈❛♥✐s❤❡s ✇❤❡♥ q(Z) ✐s ❡q✉❛❧ t♦ t❤❡ tr✉❡ ♣♦st❡r✐♦r✳

❋r♦♠ ♥♦✇ ♦♥✱ ✇❡ ❛ss✉♠❡ t❤❡ ❢♦❧❧♦✇✐♥❣ ❢❛❝t♦r✐③❛t✐♦♥ ♦❢ t❤❡ ✈❛r✐❛t✐♦♥❛❧ ❞✐s✲

tr✐❜✉t✐♦♥ q( Z )✿

q( Z ) = Y M

i=1

q i ( Z _i ). ✭✸✵✮

■❢ ✇❡ ❡♠❜❡❞ t❤✐s ❢❛❝t♦r✐③❛t✐♦♥ ✐♥t♦ t❤❡ ❢r❡❡ ❡♥❡r❣② ❣✐✈❡♥ ✐♥ ✭✷✽✮ ❛♥❞ ❞✐ss❡❝t

♦✉t t❤❡ ❞❡♣❡♥❞❡♥❝② ♦♥ ♦♥❡ ♦❢ t❤❡ ❢❛❝t♦rs q i ( Z _i )✱ ✇❡ ♦❜t❛✐♥

L (q) = Z

q i

n Z log p(X, Z) Y

i

^′6=i

q i

^′

dZ i

^′

o dZ i − Z

q i log q i dZ i + ❝♦♥st, ✭✸✶✮

= Z

q i log ˜ p(X, Z _i )dZ i − Z

q i log q i dZ i + ❝♦♥st, ✭✸✷✮

= Z

q i log p(X, ˜ Z _i ) q i

dZ i + ❝♦♥st, ✭✸✸✮

✇❤❡r❡

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞ ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥ ✾

log ˜ p(X, Z _i ) = Z

log p(X, Z) Y

i

^′6=i

q i

^′

dZ i

^′

+ const, ✭✸✹✮

= E i

^′6=i

[log p(X, Z)] + ❝♦♥st ✭✸✺✮

❛♥❞ t❤❡ ♥♦r♠❛❧✐③✐♥❣ ❝♦♥st❛♥t ✐s s✉❝❤ t❤❛t p(X, ˜ Z _i ) ✐s ❛ ♣r♦♣❡r ❞✐str✐❜✉t✐♦♥✳

◆♦✇✱ s✉♣♣♦s❡ t❤❛t ✇❡ ❦❡❡♣ q i

^′6=i

❝♦♥st❛♥t ❛♥❞ ♠❛①✐♠✐③❡ t❤❡ ❢r❡❡ ❡♥❡r❣② s❤♦✇♥ ✐♥ ✭✷✽✮ ✇rt✳ q i ✳ ❚❤❡ ♠✐♥✐♠✉♠ ♦❝❝✉rs ✇❤❡♥ q i (Z i ) = ˜ p(X, Z _i )✳ ❆s ❛ r❡s✉❧t✱ ✇❡ ♦❜t❛✐♥ ❛ ❣❡♥❡r❛❧ ❡q✉❛t✐♦♥ ❢♦r t❤❡ s♦❧✉t✐♦♥ ❜② ♠❛①✐♠✐③✐♥❣ t❤❡ ❢r❡❡

❡♥❡r❣② ❛s ❢♦❧❧♦✇s

q

^∗

_i (Z i ) = ˜ p(X, Z _i ). ✭✸✻✮

◆♦t❡ t❤❛t ✐♥ t❤✐s ❡q✉❛t✐♦♥✱ t❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ♦❢ t❤❡ ♦♣t✐♠❛❧ ❛♣♣r♦①✐♠❛t✐♥❣

❞✐str✐❜✉t✐♦♥ q _i

^∗

(Z i ) ❞❡♣❡♥❞s ♦♥ t❤❡ ❡①♣❡❝t❛t✐♦♥ ♦❢ t❤❡ log ♦❢ t❤❡ ❥♦✐♥t ❞✐str✐❜✉t✐♦♥

✇rt✳ ❛❧❧ ♦t❤❡r ✈❛r✐❛t✐♦♥❛❧ ❞✐str✐❜✉t✐♦♥s✳ ■♥ t❤❛t s❡♥s❡✱ ✭✸✻✮ ✐♥❞✐❝❛t❡s ❛ s❡t ♦❢

❡q✉❛t✐♦♥s ❢♦r i = { 1, . . . , M } ✳ ❚❤❡r❡❢♦r❡ ❛♥ ✐t❡r❛t✐✈❡ ✉♣❞❛t❡ ♣r♦❝❡❞✉r❡ ✐s ♥❡❡❞❡❞✳

❆❢t❡r ♣r♦♣❡r ✐♥✐t✐❛❧✐③❛t✐♦♥ ♦❢ ❛❧❧ t❤❡ ✈❛r✐❛t✐♦♥❛❧ ❞✐str✐❜✉t✐♦♥s✱ ❡❛❝❤ ❞✐str✐❜✉t✐♦♥

✐s ✉♣❞❛t❡❞ ✐♥ ❛♥ ✐t❡r❛t✐✈❡ ❝②❝❧❡✳

■♥ ♣r❛❝t✐❝❡✱ ✭✸✻✮ ✐s ❛♣♣❧✐❝❛❜❧❡ ♦♥❧② ✇❤❡♥ E i

^′6=i

[log p(X, Z)] ✐s ❝♦♠♣✉t❛❜❧❡ ✐♥

❝❧♦s❡❞ ❢♦r♠ ❛♥❞ ❝♦rr❡s♣♦♥❞s t♦ ❛ ❦♥♦✇♥ ♣❛r❛♠❡tr✐❝ ❞✐str✐❜✉t✐♦♥ ❢♦r ✇❤✐❝❤ t❤❡

♥♦r♠❛❧✐③✐♥❣ ❝♦♥st❛♥t ✐s ❝♦♠♣✉t❛❜❧❡ ✐♥ ❝❧♦s❡❞ ❢♦r♠✳ ❲❤❡♥ t❤✐s ✐s ♥♦t t❤❡ ❝❛s❡✱

p(X, Z) ♠✉st ❜❡ r❡♣❧❛❝❡❞ ❜② ❛ ❧♦✇❡r ❜♦✉♥❞ ❢♦r ✇❤✐❝❤ t❤❡ r❡s✉❧t✐♥❣ ❛♣♣r♦①✐♠❛t✲

✐♥❣ ❞✐str✐❜✉t✐♦♥ ❜❡❝♦♠❡s tr❛❝t❛❜❧❡✳

▲❡t ✉s ❝♦♥s✐❞❡r ❛ ♣❛r❛♠❡tr✐❝ t❤❡ ❧♦✇❡r ❜♦✉♥❞ f( X , Z , Ω ) ♦❢ p( X , Z ) s✉❝❤

t❤❛t

p(X, Z) ≥ f (X, Z, Ω), ✭✸✼✮

✇❤❡r❡ Ω ✐s ❛ s❡t ♦❢ ❛✉①✐❧✐❛r② ✈❛r✐❛❜❧❡s✳ ❯s✐♥❣ t❤✐s ❞❡✜♥✐t✐♦♥✱ ✇❡ ❞❡✜♥❡ B ✱ ✇❤✐❝❤

❢✉rt❤❡r ❧♦✇❡r ❜♦✉♥❞s L ❛s ✐♥ t❤❡ ❢♦❧❧♦✇✐♥❣

L (q) ≥ B (q, Ω) = Z

q(Z) log f (X, Z, Ω)

q(Z) dZ. ✭✸✽✮

❯s✐♥❣ B (q, Ω)✱ ✇❡ r❡✇r✐t❡ t❤❡ ♠❛r❣✐♥❛❧ ❞✐str✐❜✉t✐♦♥ ❣✐✈❡♥ ✐♥ ✭✷✼✮ ❛s ❢♦❧❧♦✇s log p(X) = max

Ω

B (q, Ω) + ( L (q) − max

Ω

B (q, Ω)) + KL(q || p). ✭✸✾✮

❍❡r❡ ✇❡ ♠❛①✐♠✐③❡ t❤❡ ❧♦✇❡r ❜♦✉♥❞ B (q, Ω) ✇rt✳ Ω ✱ ✇❤✐❝❤ t✐❣❤t❡♥s t❤❡ ❧♦✇❡r

❜♦✉♥❞ t♦ t❤❡ ❢r❡❡ ❡♥❡r❣② L (q)✳ ❯s✐♥❣ t❤❡ ❢❛❝t♦r✐③❛t✐♦♥ ✇❡ ✐♥tr♦❞✉❝❡❞ ✐♥ ✭✸✵✮

❛♥❞ ❞✐ss❡❝t✐♥❣ ♦✉t t❤❡ ❞❡♣❡♥❞❡♥❝② ♦♥ ♦♥❡ ♦❢ t❤❡ ❢❛❝t♦rs q i ( Z _i )✱ ✇❡ ♦❜t❛✐♥

B (q, Ω) = Z

q i log f ˜ (X, Z _i , Ω) q i

dZ i + const, ✭✹✵✮

✇❤❡r❡ log ˜ f (X, Z _i , Ω) ✐s ❞❡✜♥❡❞ ❛s

log ˜ f (X, Z _i , Ω) = Z

log f (X, Z, Ω) Y

i

^′6=i

q i

^′

dZ i

^′

+ const,

= E i

^′6=i

[log f ( X , Z , Ω )] + const, ✭✹✶✮

✶✵ ❆❞✐❧♦➜✉ ✫ ❱✐♥❝❡♥t

✇❤❡r❡ t❤❡ ♥♦r♠❛❧✐③✐♥❣ ❝♦♥st❛♥t ✐s s✉❝❤ t❤❛t f ˜ (X, Z _i , Ω) ✐s ❛ ♣r♦♣❡r ♣r♦❜❛❜✐❧✐t②

❞✐str✐❜✉t✐♦♥✳

❍❡♥❝❡✱ ♠❛①✐♠✐③✐♥❣ t❤❡ ❧♦✇❡r ❜♦✉♥❞ B (q, Ω) ✇rt✳ q i (Z i ) ♠✐♥✐♠✐③❡s ❛♥ ❛♣✲

♣r♦①✐♠❛t✐♦♥ t♦ t❤❡ ❑▲✲❞✐✈❡r❣❡♥❝❡ ❜❡t✇❡❡♥ q(Z) ❛♥❞ t❤❡ tr✉❡ ♣♦st❡r✐♦r ❞✐str✐✲

❜✉t✐♦♥ p(Z | X)✳

❋✐♥❛❧❧②✱ ✇❡ ❝♦♥❝❧✉❞❡ t❤❛t t✇♦ ❛❧t❡r♥❛t✐✈❡ st❡♣s ②✐❡❧❞s t❤❡ ❣❡♥❡r❛❧ ❡q✉❛t✐♦♥

❢♦r t❤❡ ♦♣t✐♠❛❧ ❛♣♣r♦①✐♠❛t✐♥❣ ❞✐str✐❜✉t✐♦♥s q _i

^∗

✳ ■♥ t❤❡ ✜rst st❡♣✱ ✇❡ ♠❛①✐♠✐③❡

t❤❡ ❧♦✇❡r ❜♦✉♥❞ B (q, Ω) t♦ t❤❡ ❢r❡❡ ❡♥❡r❣② L (q) ✇rt✳ t❤❡ ❛✉①✐❧✐❛r② ✈❛r✐❛❜❧❡s Ω ✱

✇❤✐❝❤ t✐❣❤t❡♥s t❤❡ ❧♦✇❡r ❜♦✉♥❞✱ ❛♥❞ ✐♥ t❤❡ s❡❝♦♥❞ st❡♣✱ ✇❡ ♠❛①✐♠✐③❡ B (q, Ω )

✇rt✳ t❤❡ ❛♣♣r♦①✐♠❛t✐♥❣ ❞✐str✐❜✉t✐♦♥s q i ✳

❚❤❡ ♦♣t✐♠❛❧ ❛♣♣r♦①✐♠❛t✐♥❣ ❞✐str✐❜✉t✐♦♥ q

^∗

_i ( Z _i ) ✐s ❣✐✈❡♥ ❜②

q

^∗

_i ( Z _i ) = ˜ f ( X , Z _i , Ω ). ✭✹✷✮

■♥ t❤❡ ❢♦❧❧♦✇✐♥❣✱ ✇❡ ❛❞♦♣t t❤✐s str❛t❡❣② ❢♦r t❤❡ ❞❡r✐✈❛t✐♦♥ ♦❢ t❤❡ ❛♣♣r♦①✲

✐♠❛t✐♥❣ ❞✐str✐❜✉t✐♦♥s ♦❢ t❤❡ ♠✉❧t✐❧❡✈❡❧ ◆▼❋ ♣❛r❛♠❡t❡rs ❛♥❞ t❤❡ s♦✉r❝❡ ❝♦♠✲

♣♦♥❡♥ts s✐♥❝❡ E[log p(S | V)] ✐s ♥♦t tr❛❝t❛❜❧❡ ✐♥ ❝❧♦s❡❞ ❢♦r♠ ❛s ✇❡ ✇✐❧❧ s❤♦✇ ✐♥

❙❡❝t✐♦♥ ✷✳✷✳✶✳

✷✳✷ ❆♣♣❧✐❝❛t✐♦♥ t♦ t❤❡ Pr♦♣♦s❡❞ ▼♦❞❡❧

P✉rs✉✐♥❣ t❤❡ ❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s✐❛♥ ❛♣♣r♦❛❝❤✱ ✇❡ ❝♦♥s✐❞❡r t❤❡ ❢♦❧❧♦✇✐♥❣ ♠❡❛♥

✜❡❧❞ ❢❛❝t♦r✐③❛t✐♦♥ ❢♦r q(Z)✿

q(Z) = Y

f,n

q(s f n ) Y

f

q( A _f )) Y

j,m,n

q(h ^ex _j,mn ) Y

j,k,m

q(g _j,km ^ex ) Y

j,k,l

q(u ^ex _j,lk ) Y

j,f,l

q(w ^ex _{j,f l} ) Y

j,m

^′

,n

q(h ^ft _j,m

′

n ) Y

j,k

^′

,m

^′

q(g _j,k ^ft

′

m

^′

) Y

j,k

^′

,l

^′

q(u ^ft _j,l

′

k

^′

) Y

j,f,l

^′

q(w ^ft _{j,f l}

′

)

. ✭✹✸✮

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞ ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥ ✶✶

✷✳✷✳✶ ❆✉①✐❧✐❛r② ❱❛r✐❛❜❧❡s

❋♦r t❤❡ s❛❦❡ ♦❢ r❡❛❞✐❜✐❧✐t②✱ ❧❡t ✉s ❞❡✜♥❡ η = { k, m, l } t❤❡ ❥♦✐♥t ✐♥❞❡① ♦❢ t❤❡

❡①❝✐t❛t✐♦♥ ◆❚❋ ♣❛r❛♠❡t❡rs ❛♥❞ η

^′

= { k

^′

, m

^′

, l

^′

} t❤❡ ❥♦✐♥t ✐♥❞❡① ♦❢ t❤❡ ✜❧t❡r

◆❚❋ ♣❛r❛♠❡t❡rs✳ ❲✐t❤ t❤❡s❡ ❥♦✐♥t ✐♥❞✐❝❡s ❧❡t ✉s ❢✉rt❤❡r ❞❡✜♥❡ v j,f n,η,η

^′

❛s t❤❡

♣r♦❞✉❝t ♦❢ t❤❡ ◆❚❋ ♣❛r❛♠❡t❡rs

v j,f n,η,η

^′

= h ^ex _j,mn g ^ex _j,km u ^ex _j,lk w ^ex _{j,f l} h ^ft _j,m

′

n g ^ft _j,k

′

m

^′

u ^ft _j,l

′

k

^′

w _{j,f l} ^ft

′

. ✭✹✹✮

▲❡t ✉s ❢✉rt❤❡r ❞❡✜♥❡ v ^ex _{j,f n,η} ❛s t❤❡ ♣r♦❞✉❝t ♦❢ t❤❡ ❡①❝✐t❛t✐♦♥ ❝♦❡✣❝✐❡♥ts ♦❢ t❤❡

◆❚❋ ❝♦♠♣♦♥❡♥ts ❛♥❞ v _{j,f n,η} ^ft

′

❛s t❤❡ ♣r♦❞✉❝t ♦❢ t❤❡ ✜❧t❡r ❝♦❡✣❝✐❡♥ts

v _{j,f n,η} ^ex = h ^ex _j,mn g ^ex _j,km u ^ex _j,lk w ^ex _{j,f l} , ✭✹✺✮

v _{j,f n,η} ^ft

′

= h ^ft _j,m

′

n g ^ft _j,k

′

m

^′

u ^ft _j,l

′

k

^′

w _{j,f l} ^ft

′

. ✭✹✻✮

❍❛✈✐♥❣ ❞❡✜♥❡❞ t❤❡s❡ ♥♦t❛t✐♦♥s✱ ❧❡t ✉s ❤❛✈❡ ❛ ❧♦♦❦ ❛t E[log p( S | V )] ♠♦r❡ ❝❧♦s❡❧②✿

E [log p( S | V )] = E h log Y

f,n

N ( s

_{f n}

|0, Σ

^s,f n

) i

= E h X

f,n

log N

s

_{f n}

|0, diag X

η

X

η^′

v

j,f n,η,η′

i ,

= E h X

f,n

−R log π − log det

diag X

η

X

η^′

v

j,f n,η,η′

− s

^H_{f n}

diag X

η

X

η^′

v

j,f n,η,η′

−1

s

_{f n}

i ,

= X

f,n

−R log π + X

j

−R

j

E h

log X

η

X

η^′

v

j,f n,η,η^′

i

+ X

j,r

−E[|s

jr,f n

|

²

]E h 1 P

η

P

η^′

v

j,f n,η,η^′

i

. ✭✹✼✮

❆s ♦♥❡ ❝❛♥ ❡❛s✐❧② s❡❡✱ ♥♦♥❡ ♦❢ t❤❡ t✇♦ ❡①♣❡❝t❛t✐♦♥s ✐♥ t❤✐s ❡q✉❛t✐♦♥ ❛❜♦✈❡

✐s tr❛❝t❛❜❧❡✳ ❙♦✱ ✇❡ r❡s♦rt t♦ t❤❡ ❛❧t❡r♥❛t✐✈❡ ♠❡t❤♦❞✱ ✇❤✐❝❤ ✇❡ ✐♥tr♦❞✉❝❡❞ ✐♥

❙❡❝t✐♦♥ ✷✳✶ ❛♥❞ ❧♦✇❡r ❜♦✉♥❞ p(S | V) ❛s ♣r♦♣♦s❡❞ ✐♥ ❬✸❪✳

❋♦r t❤❡ ✜rst ❡①♣❡❝t❛t✐♦♥✱ ❣✐✈❡♥ t❤❛t x → − log x ✐s ❝♦♥✈❡①✱ ✇❡ ❝❛♥ ❧♦✇❡r

❜♦✉♥❞ ✐t ❜② ✐ts ✜rst✲♦r❞❡r ❚❛②❧♦r s❡r✐❡s ❡①♣❛♥s✐♦♥ ❛r♦✉♥❞ ❛♥ ❛r❜✐tr❛r② ♣♦s✐t✐✈❡

♣♦✐♥t ω j,f n ❛s ❢♦❧❧♦✇s

− log X

η

X

η′

v

j,f n,η,η^′

≥ − log ω

j,f n

− 1 ω

j,f n

( X

η

X

η′

v

j,f n,η,η^′

− ω

j,f n

),

= − log ω

j,f n

+ 1 − 1 ω

j,f n

X

η

X

η^′

v

j,f n,η,η^′

. ✭✹✽✮

❋♦r t❤❡ s❡❝♦♥❞ ❡①♣❡❝t❛t✐♦♥✱ ❣✐✈❡♥ t❤❛t x →

⁻¹

x ✐s ❝♦♥❝❛✈❡✱ ❢♦r ❛♥② ♣♦s✐t✐✈❡

φ j,f n,η,η

^′

s✉❝❤ t❤❛t P

η

P

η

^′

φ j,f n,η,η

^′

= 1✱ ✉s✐♥❣ ❏❡♥s❡♥✬s ✐♥❡q✉❛❧✐t②✿

✶✷ ❆❞✐❧♦➜✉ ✫ ❱✐♥❝❡♥t

− 1

P

η

P

η

^′

v j,f n,η,η

^′

= − 1

P

k φ j,f n,η,η

^′

v

j,f n,η,η′

φ

j,f n,η,η′

≥ − X

k

φ j,f n,η,η

^′

1

v

j,f n,η,η′

φ

j,f n,η,η′

= − X

η

X

η

^′

φ ² _{j,f n,η,η}

′

1 v j,f n,η,η

^′

. ✭✹✾✮

❲✐t❤ t❤❡s❡ t✇♦ ✐♥❡q✉❛❧✐t✐❡s✱ ✇❡ ❝❛♥ ❧♦✇❡r ❜♦✉♥❞ log p(S | V) ✉s✐♥❣ t❤❡ ❛✉①✲

✐❧✐❛r② ✈❛r✐❛❜❧❡s Ω = {{ ω j,f n } ^{j,f n} , { φ j,f n,η,η

^′

} ^{j,f n,η,η}

^′

} ❛s ❢♦❧❧♦✇s log p( S | V ) ≥ −F · N · R · log π

+ X

j,f n

R

j

− log ω

j,f n

+ 1 − 1 ω

j,f n

X

η

X

η^′

v

j,f n,η,η′

+ X

j,f n

X

r

−|s

jr,f n

|

²

X

η

X

η′

φ

²j,f n,η,η^′

1 v

j,f n,η,η′

. ✭✺✵✮

✷✳✷✳✷ ❚✐❣❤t❡♥✐♥❣ t❤❡ ❇♦✉♥❞ ✇rt✳ t❤❡ ❆✉①✐❧✐❛r② ❱❛r✐❛❜❧❡s

❚❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥s ❢♦r Ω ❛r❡ ♦❜t❛✐♥❡❞ ❜② ♠❛①✐♠✐③✐♥❣ t❤❡ ❜♦✉♥❞ B (q, Ω)✳

❈♦♥❝❡r♥✐♥❣ ω j,f n ✱ ✇❡ s✐♠♣❧② t❛❦❡ t❤❡ ♣❛rt✐❛❧ ❞❡r✐✈❛t✐✈❡ ♦❢ t❤❡ ❜♦✉♥❞ B (q, Ω)

✇✳r✳t✳ ω j,f n ✇❤✐❝❤ ✐s ❣✐✈❡♥ ❜② B (q, Ω) = − F · N · R · log π

+ X

j,f n

R

j

− log ω

j,f n

+ 1 − 1 ω

j,f n

X

η

X

η^′

E [v

j,f n,η,η^′

]

+ X

j,f n

X

r

−|s

jr,f n

|

²

X

η

X

η^′

φ

²j,f n,η,η^′

E h 1 v

j,f n,η,η^′

i

+ const. ✭✺✶✮

❙♦✱ t❤❡ ❞❡r✐✈❛t✐✈❡ ✐s ❣✐✈❡♥ ❛s

∂ B (q, Ω)

∂ω j,f n

= − R j

ω j,f n

+ R j

ω _{j,f n} ² X

η

X

η

^′

E[v j,f n,η,η

^′

] ✭✺✷✮

❛♥❞ ♠❛❦❡ ✐t ❡q✉❛❧ t♦ ③❡r♦✱ ✇❤✐❝❤ ②✐❡❧❞s ω j,f n = X

η

X

η

^′

E[v j,f n,η,η

^′

]. ✭✺✸✮

❋♦r φ j,f n,η,η

^′

✱ ✇❡ ✉s❡ ▲❛❣r❛♥❣❡ ♠✉❧t✐♣❧✐❡rs δ j,f n ✱ ❜❡❝❛✉s❡ ♦❢ t❤❡ ❝♦♥str❛✐♥t✳

❚❤❡ ▲❛❣r❛♥❣✐❛♥ ✐s ❣✐✈❡♥ ❜② B (q, Ω) = X

j,f n

X

r

−E [|s

jr,f n

|

²

] X

η

X

η′

φ

²j,f n,η,η^′

E h 1 v

j,f n,η,η′

i

+ δ

j,f n

X

η

X

η^′

φ

j,f n,η,η′

− 1

+ const. ✭✺✹✮

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞ ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥ ✶✸

❚❛❦✐♥❣ t❤❡ ♣❛rt✐❛❧ ❞❡r✐✈❛t✐✈❡ ✇✐t❤ r❡s♣❡❝t t♦ φ j,f n,η,η

^′

❛♥❞ δ j,f n ②✐❡❧❞s t❤❡

❢♦❧❧♦✇✐♥❣ s②st❡♠ ♦❢ ❡q✉❛t✐♦♥s✿

∂ B (q, Ω)

∂φ

j,f n,c,η,η′

= X

r

−E [|s

jr,f n

|

²

] X

η

X

η′

φ

²j,f n,η,η^′

E h 1 v

j,f n,η,η′

i ✭✺✺✮

∂ B (q, Ω)

∂δ

j,f n

= X

η

X

η^′

φ

j,f n,η,η′

− 1. ✭✺✻✮

❙♦❧✈✐♥❣ t❤❡ s②st❡♠ ❢♦r φ j,f n,η,η

^′

②✐❡❧❞s φ j,f n,η,η

^′

= 1

C j,f n E h 1

v j,f n,η,η

^′

i

−1

, ✭✺✼✮

✇❤❡r❡ C j,f n ✐s t❤❡ ♥♦r♠❛❧✐③❛t✐♦♥ ❝♦♥st❛♥t ❣✐✈❡♥ ❜② C j,f n = X

η

X

η

^′

E h 1

v j,f n,η,η

^′

i

−1

. ✭✺✽✮

✷✳✷✳✸ ❱❛r✐❛t✐♦♥❛❧ ❯♣❞❛t❡s ❢♦r t❤❡ ◆❚❋ P❛r❛♠❡t❡rs

■♥ t❤✐s s❡❝t✐♦♥✱ ✇❡ ✇✐❧❧ ❞❡t❡r♠✐♥❡ t❤❡ ❛♣♣r♦①✐♠❛t✐♥❣ q ❞✐str✐❜✉t✐♦♥s ♦❢ t❤❡ ◆❚❋

♣❛r❛♠❡t❡rs ❛♥❞ ❞❡r✐✈❡ t❤❡ ❝♦rr❡s♣♦♥❞✐♥❣ ✉♣❞❛t❡ ❡q✉❛t✐♦♥s✳ ❋♦r t❤✐s ✇❡ ✇✐❧❧ ✉s❡

t❤❡ t❡♠♣❧❛t❡ ❣✐✈❡♥ ✐♥ ✭✹✶✱ ✹✷✮✳

❯♣❞❛t❡ ❊q✉❛t✐♦♥s ❢♦r w ^ex _{j,f l} ✿ ❚❤❡ ♣r♦❜❛❜✐❧✐t② ❞✐str✐❜✉t✐♦♥ f ˜ (X, w ^ex _{j,f l} , Ω)

❞❡✜♥❡❞ ✐♥ ✭✹✶✮ ✐s ❣✐✈❡♥ ❜②

log q

^∗

(w

^exj,f l

) = w

j,f l^ex

X

n

− R

j

ω

j,f n

X

k,m

X

η^′

E [h

^exj,mn

g

j,km^ex

u

^exj,lk

v

j,f n,η^ft ′

]

− X

n

X

r

E [|s

jr,f n

|

²

] w

^ex_{j,f l}

X

k,m

X

η^′

φ

²j,f n,η,η^′

E h 1

h

^ex_j,mn

g

^ex_j,km

u

^ex_j,lk

v

_{j,f n,η}^ft _′

i

− log w

^exj,f l

+ const. ✭✺✾✮

❖❜s❡r✈✐♥❣ t❤✐s ❞✐str✐❜✉t✐♦♥✱ ♦♥❡ ❝❛♥ s❡❡ t❤❛t ✐t ✐♥✈♦❧✈❡s ❛ ❧✐♥❡❛r t❡r♠ ✐♥

log w _{j,f l} ^ex ✱ ❛ ❧✐♥❡❛r t❡r♠ ✐♥ w ^ex _{j,f l} ❛♥❞ ❛ ❧✐♥❡❛r t❡r♠ ✐♥ _w

^ex

¹

j,f l

✳ ❚❤❡ ♦♣t✐♠❛❧ ❛♣♣r♦①✲

✐♠❛t✐♥❣ ❞✐str✐❜✉t✐♦♥ q

^∗

(w _{j,f l} ^ex ) ✐s ❤❡♥❝❡ ❛♥ ✐♥st❛♥❝❡ ♦❢ t❤❡ ❣❡♥❡r❛❧✐③❡❞ ✐♥✈❡rs❡

●❛✉ss✐❛♥ ✭●■●✮ ❞✐str✐❜✉t✐♦♥✱ ✇❤♦s❡ ♣r♦❜❛❜✐❧✐t② ❞✐str✐❜✉t✐♦♥ ❢✉♥❝t✐♦♥ ✭P❉❋✮ ✐s

❣✐✈❡♥ ❜②

GIG(y; γ, ρ, τ) = exp { (γ − 1) log y − ρy − ^τ y } ρ

^γ2

2τ

^γ2

K γ (2 √ ρτ ) , ✭✻✵✮

❢♦r y ≥ 0✱ ρ ≥ 0 ❛♥❞ τ ≥ 0✱ ✇❤❡r❡ K γ ( · ) ✐s t❤❡ ♠♦❞✐✜❡❞ ❇❡ss❡❧ ❢✉♥❝t✐♦♥ ♦❢ t❤❡

s❡❝♦♥❞ ❦✐♥❞✳ ❚❤❡ ❣❛♠♠❛ ❞✐str✐❜✉t✐♦♥ ✐s ❛ s♣❡❝✐❛❧ ❝❛s❡ ♦❢ t❤❡ ●■● ❞✐str✐❜✉t✐♦♥ ❬✹❪

✇❤❡♥ τ = 0 ❛♥❞ γ > 0✳ ❙✐♠✐❧❛r❧②✱ t❤❡ ✐♥✈❡rs❡ ❣❛♠♠❛ ❞✐str✐❜✉t✐♦♥ ✐s ❛♥♦t❤❡r s♣❡❝✐❛❧ ❝❛s❡ ❬✹❪ ✇❤❡♥ ρ = 0 ❛♥❞ γ < 0✳

■♥ t❤❡ ❡①♣♦♥❡♥t ♦❢ t❤❡ P❉❋ ♦❢ t❤❡ ●■● ❞✐str✐❜✉t✐♦♥✱ ✇❡ ❝❛♥ ♠❛t❝❤ ^τ _y t♦

t❤❡ ✜rst ❧✐♥❡ ♦❢ ✭✺✾✮ ✐♥ ❛ ✏❝♦♠♣❧❡t✐♥❣ t❤❡ sq✉❛r❡✑ ❢❛s❤✐♦♥ ❬✷❪✳ ❙✐♠✐❧❛r❧②✱ ρy ✐s

✶✹ ❆❞✐❧♦➜✉ ✫ ❱✐♥❝❡♥t

♠❛t❝❤❡❞ t♦ t❤❡ s❡❝♦♥❞ ❧✐♥❡ ♦❢ ✭✺✾✮✳ ❋✐♥❛❧❧②✱ t❤❡ ❧❛st ❧✐♥❡ ♦❢ ✭✺✾✮ ✐s ♠❛t❝❤❡❞ t♦

(γ − 1) log y✳ ❇② ❞♦✐♥❣ t❤✐s ✇❡ ♦❜t❛✐♥ t❤❡ ❢♦❧❧♦✇✐♥❣ ✉♣❞❛t❡ ❡q✉❛t✐♦♥s ❢♦r t❤❡

♣❛r❛♠❡t❡r ♦❢ q

^∗

(w _{j,f l} ^ex ) τ _{w,j,f l} ^ex ✱ ρ ^ex _{w,j,f l} ❛♥❞ γ _{w,j,f l} ^ex

τ _{w,j,f l} ^ex = X

n

X

r

E[ | s jr,f n | ² ] X

k,m

X

η

^′

φ ² _{j,f n,η,η}

′

E h 1

h ^ex _j,mn g ^ex _j,km u ^ex _j,lk v ^ft _{j,f n,η}

′

i , ✭✻✶✮

ρ ^ex _{w,j,f l} = X

n

R j

ω j,f n

X

k,m

X

η

^′

E[h ^ex _j,mn g _j,km ^ex u ^ex _j,lk v _{j,f n,η} ^ft

′

], ✭✻✷✮

γ _{w,j,f l} ^ex = 0. ✭✻✸✮

❊♠❜❡❞❞✐♥❣ t❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ❢♦r φ j,f n,η,η

^′

❣✐✈❡♥ ✐♥ ✭✺✼✮ ✐♥t♦ ✭✻✶✮✱ ✇❡

♦❜t❛✐♥ t❤❡ ❢♦❧❧♦✇✐♥❣✿

τ

w,j,f l^ex

= X

n

"

X

r

E [|s

jr,f n

|

²

]

X

k,m

X

η^′

1

C

j,f n

E h 1

h

^ex_j,mn

g

^ex_j,km

u

^ex_j,lk

w

^ex_{j,f l}

v

_{j,f n,η}^ft _′

i

−1

²

E h 1

h

^ex_j,c,mn

g

_j,km^ex

u

^ex_j,lk

v

^ft_{j,f n,η′}

i

!#

= E h 1 w

^ex_{j,c,f l}

i

−2

X

n

1 C

j,f n

2

X

r

E [|s

jr,f n

|

²

]

X

k,m

X

η^′

E h 1

h

^ex_j,mn

g

_j,km^ex

u

^ex_j,lk

v

^ft_{j,f n,η′}

i

−1

!

. ✭✻✹✮

❋✐♥❛❧❧②✱ ✇❡ ❝❛♥ ✇r✐t❡ t❤✐s ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ✐♥ ♠❛tr✐① ❢♦r♠ ❛s s❤♦✇♥ ❜❡❧♦✇✿

τ ^ex _w,j = E h

1

W^ex

j

i .−2

⊙

E[ | S _j | ^.2 ] ⊙ C ^.−2 _j ⊙ E h 1 V ^ft _j

i .−1

E h 1

U ^ex _j i .−1

E h 1 G ^ex _j

i .−1

E h 1 H ^ex _j

i .−1 T ! . ✭✻✺✮

◆♦t❡ t❤❛t ✐♥ ✭✻✺✮✱ t❤❡ ♣♦✇❡r ♦♣❡r❛t✐♦♥s ❧✐❦❡ X ^.−a ❛r❡ ❡❧❡♠❡♥t✲✇✐s❡ ♦♣❡r❛✲

t✐♦♥s✳ ❋✉rt❤❡r♠♦r❡✱ t❤❡ s②♠❜♦❧ ⊙ ♠❡❛♥s ❡❧❡♠❡♥t✲✇✐s❡ ♠❛tr✐① ♠✉❧t✐♣❧✐❝❛t✐♦♥✳

❙✐♠✐❧❛r❧②✱ r❡♣❧❛❝✐♥❣ ω j,f n ✐♥ ✭✻✻✮ ✇✐t❤ ✐ts ✉♣❞❛t❡ ❡q✉❛t✐♦♥ s❤♦✇♥ ✐♥ ✭✺✸✮

②✐❡❧❞s t❤❡ ❢♦❧❧♦✇✐♥❣✿

ρ ^ex _{w,j,f l} = X

n

R j

P

η

P

η

^′

E[v j,f n,η,η

^′

] X

k,m

X

η

^′

E[h ^ex _j,mn g ^ex _j,km u ^ex _j,lk v _{j,f n,η} ^ft

′

]

. ✭✻✻✮

❚❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ♦❢ ρ ^ex _w,j ✐s ✇r✐tt❡♥ ✐♥ t❤❡ ♠❛tr✐① ❢♦r♠ ❛s ❢♦❧❧♦✇s✿

ρ ^ex _w,j = R j E[V _j ^ex ] ^.−1 E[U ^ex _j ]E[G ^ex _j ]E[H ^ex _j ] T

. ✭✻✼✮

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞ ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥ ✶✺

❋♦r t❤❡ ♦t❤❡r ◆❚❋ ♣❛r❛♠❡t❡rs✱ t❤❡ ❞❡r✐✈❛t✐♦♥s ❛r❡ ♣❡r❢♦r♠❡❞ ❜② ❢♦❧❧♦✇✐♥❣

t❤❡ s❛♠❡ st❡♣s✳ ❚❤❡r❡❢♦r❡✱ ✐♥ t❤❡ ❢♦❧❧♦✇✐♥❣✱ ✇❡ s❦✐♣ t❤❡ ❞❡t❛✐❧s ♦❢ t❤❡ ❞❡r✐✈❛t✐♦♥s

❛♥❞ ❣✐✈❡ ♦♥❧② t❤❡ ✜♥❛❧ ✉♣❞❛t❡ ❡q✉❛t✐♦♥s✳

❯♣❞❛t❡ ❊q✉❛t✐♦♥s ❢♦r u ^ex _j,lk ✿ ❚❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ❢♦r τ _u,j,lk ^ex ✐s ❣✐✈❡♥ ✐♥ t❤❡

❢♦❧❧♦✇✐♥❣

τ _u,j,lk ^ex =E h 1 u ^ex _j,lk

i

−2

X

f,n

1 C j,f n 2

X

r

E[ | s jr,f n | ² ] X

m

X

η

^′

E

h 1

h ^ex _j,mn g _j,km ^ex w _{j,f l} ^ex v _{j,f n,η} ^ft

′

i

−1

. ✭✻✽✮

❚❤❡ ♠❛tr✐① ✈❡rs✐♦♥ ♦❢ t❤✐s ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ✐s ✇r✐tt❡♥ ❛s

τ ^ex _u,j = E q

h 1 U ^ex _j

i .−2

⊙

"

E q

h 1 W ^ex _j,c

i .−1 T

E[ | S _j | ^.2 ] ⊙ C ^.−2 _j ⊙ E h 1 V ^ft _j,c

i .−1

E

h 1 G ^ex _j,c

i .−1

E h 1

H ^ex _j,c

i .−1 T #

. ✭✻✾✮

❚❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ❢♦r ρ ^ex _u,j,lk ✐s ❣✐✈❡♥ ✐♥ t❤❡ ❢♦❧❧♦✇✐♥❣

ρ ^ex _u,j,lk = X

f,n

R j

P

η

P

η

^′

E[v j,f n,η,η

^′

] X

m

X

η

^′

E[h ^ex _j,mn g ^ex _j,km w ^ex _{j,f l} v _{j,f n,η} ^ft

′

]

. ✭✼✵✮

❚❤❡ ♠❛tr✐① ❢♦r♠ ✐❢ ❣✐✈❡♥ ❜②

ρ ^ex _u,j = R j E[W j ] ^T E[V ^ex _j ] ^.−1 E[G ^ex _j ]E[H ^ex _j ] T

. ✭✼✶✮

❋✐♥❛❧❧②✱

γ ^ex _u,j,lk = 0. ✭✼✷✮

❯♣❞❛t❡ ❊q✉❛t✐♦♥s ❢♦r g ^ex _j,km ✿ ❚❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ❢♦r τ _g,j,km ^ex ✐s ✇r✐tt❡♥ ❛s

❢♦❧❧♦✇s

τ _g,j,km ^ex = E h 1

g ^ex _j,km i

−2

X

f,n

1 C j,f n 2

X

r

E[ | s jr,f n | ² ] X

l

X

η

^′

E h 1

h ^ex _j,mn u ^ex _j,lk w ^ex _{j,f l} v ^ft _{j,f n,η}

′

i

−1

. ✭✼✸✮

❚❤❡ ♠❛tr✐① ✈❡rs✐♦♥ ✐s

✶✻ ❆❞✐❧♦➜✉ ✫ ❱✐♥❝❡♥t

τ ^ex _g,j = E h 1 G ^ex _j

i .−2

⊙ E h 1

W ^ex _j i .−1

E h 1 U ^ex _j

i .−1 T

E[ | S _j | ^.2 ] ⊙ C ^.−2 _j ⊙ E h 1 V ^ft _j

i .−1 E h 1

H ^ex _j

i .−1 T ! . ✭✼✹✮

❚❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ❢♦r ρ ^ex _g,j,km ✐s ❛s ❢♦❧❧♦✇s

ρ ^ex _g,j,km = X

f,n

R j

P

η

P

η

^′

E[v j,f n,η,η

^′

] X

l

X

η

^′

E q [h ^ex _j,mn u ^ex _j,lk w ^ex _{j,f l} v ^ft _{j,f n,η}

′

] . ✭✼✺✮

❚❤❡ ♠❛tr✐① ✈❡rs✐♦♥ ✐s

ρ ^ex _g,j = R j (E[W ^ex _j ]E[U ^ex _j ]) ^T E[V ^ex _j ] ^.−1 E[H ^ex _j ] ^T . ✭✼✻✮

❙✐♠✐❧❛r t♦ t❤❡ ♦t❤❡r ◆❚❋ ♣❛r❛♠❡t❡rs ❛❜♦✈❡✱

γ _g,j,km ^ex = 0. ✭✼✼✮

❯♣❞❛t❡ ❊q✉❛t✐♦♥s ❢♦r h ^ex _j,mn ✿ ❚❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ❢♦r τ _h,j,mn ^ex ✐s ❡①♣r❡ss❡❞

❛s ❢♦❧❧♦✇s

τ _h,j,mn ^ex = E h 1

h ^ex _j,mn

i

−2

X

f

1 C j,f n 2

X

r

E[ | s jr,f n | ² ] X

k,l

X

η

^′

E

h 1

g _j,km ^ex u ^ex _j,lk w ^ex _{j,f l} v ^ft _{j,f n,η}

′

i

−1

. ✭✼✽✮

❚❤❡ ♠❛tr✐① ✈❡rs✐♦♥

τ ^ex _h,j = E h 1 H ^ex _j

i .−2

⊙ E h 1

W ^ex _j i .−1

E h 1 U ^ex _j

i .−1

E h 1 G ^ex _j

i .−1 T

E[ | S _j | ^.2 ] ⊙ C ^.−2 _j ⊙ E h 1 V ^ft _j

i .−1 !

. ✭✼✾✮

❚❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥ ❢♦r ρ ^ex _h,j,mn ✐s ❛s ❢♦❧❧♦✇s

ρ ^ex _h,j,mn = X

f,n

R j

P

η

P

η

^′

E[v j,f n,η,η

^′

] X

k,l

X

η

^′

E[g ^ex _j,km u ^ex _j,lk w ^ex _{j,f l} v _{j,f n,η} ^ft

′

]

. ✭✽✵✮

❚❤❡ ♠❛tr✐① ✈❡rs✐♦♥ ✐s

ρ ^ex _h,j = R j E[W ^ex _j ]E[U ^ex _j ]E[G ^ex _j ] T

E[V ^ex _j ] ^.−1 . ✭✽✶✮

❆s ✇✐t❤ ❛❧❧ t❤❡ ♦t❤❡r ◆❚❋ ♣❛r❛♠❡t❡rs✱

γ _h,j,km ^ex = 0. ✭✽✷✮

❱❛r✐❛t✐♦♥❛❧ ❇❛②❡s ❢♦r ❙♦✉r❝❡ ❙❡♣❛r❛t✐♦♥ ❛♥❞ ❋❡❛t✉r❡ ❊①tr❛❝t✐♦♥ ✶✼

❊①♣❡❝t❛t✐♦♥s t♦ ❜❡ ❝♦♠♣✉t❡❞ ✐♥ t❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥s ♦❢ t❤❡ ◆❚❋

♣❛r❛♠❡t❡rs ❚❤❡ ❡①♣❡❝t❛t✐♦♥ E[ | s jr,f n | ^.2 ] ✐♥ ✭✻✶✮✱ ✭✻✽✮✱ ✭✼✸✮ ❛♥❞ ✭✼✽✮ ✐s ❝❛❧✲

❝✉❧❛t❡❞ ❛s

E[ | s jr,f n | ² ] = | (µ _{s,f n} ) jr | ² + (R

^ss

,f n ) jr,jr ✭✽✸✮

✇❤❡r❡ µ

s

,f n ❛♥❞ R

ss

,f n ❛r❡ t❤❡ ✜rst ❛♥❞ s❡❝♦♥❞ ♦r❞❡r ♣♦st❡r✐♦r ♠♦♠❡♥ts ♦❢ s _{f n}

❞❡r✐✈❡❞ ❜❡❧♦✇ ✐♥ ✭✾✶✮ ❛♥❞ ✭✾✷✮✳ ❚❤❡ ❡①♣❡❝t❛t✐♦♥s ✐♥✈♦❧✈✐♥❣ t❤❡ ◆❚❋ ♣❛r❛♠❡t❡rs

✐♥ ✭✻✷✮✱ ✭✼✵✮✱ ✭✼✺✮✱ ✭✽✵✮ ❛♥❞ ✭✻✶✮✱ ✭✻✽✮✱ ✭✼✸✮ ❛♥❞ ✭✼✽✮ ❛r❡ ❝♦♠♣✉t❡❞ ✈✐❛ t❤❡

❢♦❧❧♦✇✐♥❣ ❢♦r♠✉❧❛❡ ❢♦r t❤❡ ●■● ❞✐str✐❜✉t✐♦♥ ❬✹❪✿

E[y] = K ^γ+1 (2 √ ρτ ) √ τ

K ^γ (2 √ ρτ ) √ ρ , ✭✽✹✮

E h 1 y

i = K ^γ−1 (2 √ ρτ ) √ ρ

K ^γ (2 √ ρτ ) √ τ . ✭✽✺✮

E[V ^ex _j ] ✐s ♦❜t❛✐♥❡❞ ❛s

E[V ^ex _j ] = E[W ^ex _j ]E[U ^ex _j ]E[G ^ex _j ]E[H ^ex _j ] ✭✽✻✮

❛♥❞ E[1/V ^ft _j ] ^.−1 ✐s ❛ s❤♦rt❤❛♥❞ ♥♦t❛t✐♦♥ ❢♦r E h 1

W _j ^ft i .−1

E h 1 U ^ft _j

i .−1

E h 1 G ^ft _j

i .−1

E h 1 H ^ft _j

i .−1

. ✭✽✼✮

❋♦r t❤❡ ✜❧t❡r ◆❚❋ ♣❛r❛♠❡t❡rs✱ t❤❡ ❞❡r✐✈❛t✐♦♥ ♦❢ t❤❡ ✉♣❞❛t❡ ❡q✉❛t✐♦♥s ✐s s✐♠✐❧❛r t♦ t❤❡ ❞❡r✐✈❛t✐♦♥ ♦❢ t❤❡ ❡①❝✐t❛t✐♦♥ ◆❚❋ ♣❛r❛♠❡t❡rs ❛♥❞ s♦ ❛r❡ t❤❡ ✜♥❛❧

✉♣❞❛t❡ ❡q✉❛t✐♦♥s✳ ❚❤❡r❡❢♦r❡✱ ✇❡ s❦✐♣ t❤❡♠ ❤❡r❡✳

✷✳✷✳✹ ❱❛r✐❛t✐♦♥❛❧ ❯♣❞❛t❡s ❢♦r t❤❡ ❙♦✉r❝❡ ❈♦♠♣♦♥❡♥ts

❚❤❡ ❞✐str✐❜✉t✐♦♥ f ˜ (X, s _{f n} , Ω) ♦❢ t❤❡ s♦✉r❝❡ ❝♦♠♣♦♥❡♥ts s _{f n} ✐s ❣✐✈❡♥ ❜②

log q

^∗

(s f n ) = s ^H _{f n} µ ^H

A

,f (σ ² _b I)

⁻¹

x _{f n} + x ^H _{f n} (σ _b ² I)

⁻¹

µ

A

,f s _{f n}

− 1

σ ² _b ( s ^H _{f n} R

A

,f s _{f n} )

− X

j

X

r

| s jr,f n | ² X

η

X

η

^′

φ ² _{j,f n,η,η}

′

E h 1 v j,f n,η,η

^′

i + const. ✭✽✽✮

❘❡♣❧❛❝✐♥❣ φ j,f n,η,η

^′

✇✐t❤ ✐ts ✈❛❧✉❡ s❤♦✇♥ ✐♥ ✭✺✼✮ ②✐❡❧❞s

log q

^∗

(s f n ) = s ^H _{f n} µ ^H

A

,f (σ _b ² I)

⁻¹

x _{f n} + x ^H _{f n} (σ _b ² I)

⁻¹

µ

A

,f s _{f n}

− 1

σ ² _b (s ^H _{f n} R

A

,f s _{f n} )

− s ^H _{f n} C _{f n}

⁻¹

s _{f n} + const, ✭✽✾✮

✇❤❡r❡ µ

A

,f ❛♥❞ R

A

,f ❛r❡ t❤❡ ✜rst ❛♥❞ s❡❝♦♥❞ ♦r❞❡r ♣♦st❡r✐♦r r❛✇ ♠♦♠❡♥ts

♦❢ A _f ❞❡r✐✈❡❞ ❜❡❧♦✇ ✐♥ ✭✶✵✶✮ ❛♥❞ ✭✾✾✮✱ ❛♥❞ C _{f n}

⁻¹

= diag(C j,f n

−1

) ^R _r=1 ✐s ❛