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Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 1: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 2: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 3: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 4: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 5: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 7: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 8: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Zc]L ?> >%a(S

n

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C0 = 0. * [ * ;

C1 = 0. * [x6#;

Cn+1 = n + Cbn2 c + Cdn

2 e. * [43#;

3 !1NO) ]D# & ?u) @ @> ? => > > n)+ )u > B u) nFEM

C ′k = C2k−1

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C ′k = 2k − 2 + 2C ′

k−1

. * [ 52; FNR) 1`D#=> J*>! & 1u)B .0<La )+

C ′0 = C ′

1 = 0;F

C ′k = (k − 2)2k + 2

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(Cn)H

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Cn = Θ(n log n).. * [4;#;

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2k+1 − 1. 9H

k = log2(n + 1)|

1 Ct;-H

@)(k − 2)2k + 2 ≤ C2k−1 ≤ Cn ≤ C2k+1−1 = (k − 1)2k+1 + 2,

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Page 11: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 29: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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k≤n Xk2−k # "

U = lim Un ' "$#%?C >sI #% #F¼BJ>wF ) #ªE B ?> > " 'F ) #

Un# "

U

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[0, 1] E#%C # ") #¹@.BJIKF " > #"YB "$# I #FHB @ # ) # ?> "sF '! "YBD> #F(Bn)n∈N

BJI " #%[email protected] C #?I "'¶I #3r > # /' "YBJ> !#

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Page 32: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

69: !

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2

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Page 33: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

6 X

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Page 34: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 35: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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)+/n)+(o)+B!n) N => > FK=>")+|

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Page 37: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 38: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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>2 1/ ln 2

;-[*>u)a<> >%a(> NO) ( N

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%1Xp[_%`%11F>An) G FNO =>%1>a9 =LRQ

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Page 44: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

3%@

3 XnV D# & 9H+ D9)+qu)ED)+>7p

%1Xa5Hpq q=> >% V2qD)+ >2 `)+ o[7W

p = 3 (mod 4)H7)+ a <> a$= C>%1K/4>%P)+N '/

%`%1= )+ 9[WX `> -s<>x

= & *)n)+ & K%1Xp = 4k + 3

Hq>'n >y

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p[<W RQT)+ & G<> $= C>%1'4>%P)+L|

yH fD >2

y4k+3 = y (mod p)H*

y4k+4 = y2 = x (mod p)

m!oH2*)+ $X$C 9Hy2 = x (mod p)

H2> K)ax2k+2 = x (mod p)

[m!oH2k +2

*) !)oD#EF?%G( & ED#!o)+>>!-A >%1>!>!EGo)+ =FD)+

xH

|'n)oD# oHxk+1 [

/(<o)+ o)+>lQT-s< /%P)+$> > >%1>2P)+'Ko)`p = 1 (mod 4)

[fSV -s<>oHq<>F)+ F=>

x2k+1 = x (mod 4)H<%P) oHRQT-AX<9n)+2=>n)+2L%P) >*)+2 %`*) oH< (C>%1

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x= "9 n) Bo)+ =K%12

p

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>f = ad + bc (mod p)

;-[S7))+n)+' KPRQT-AX<> )+ %1Xu) /*)+o)+>'/o)+ =>' 2 oHf( >>u) >%1>oH*

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.(5[ * ;

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) '®@ ?> "=@Ç> ) #FF ¶F )^BJII # c + d√

x ¼B ¯F # C ?C # @ ¼@ KEB

(a−√x)(p−1)/2 )^BJII #c− d

√x

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Page 45: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

7 3%C

Zc]L ?> >! >% >p

>B = & *)n)+ & x

%1Xp/ TZ'&SL n) Lo)+ =G

x%1X

pH

* [!W p = 3 (mod 4)

H > >x(p+1)/4 (mod p)

6[!$ ?> >)+=o)+ a ∈ [[1, p − 1]]

H* N %1=>%1>2o[3[!W

a2 = x (mod p)H > >

a[

5[! )+>>EN %1>>%1>2c

>d

> & (a +

√x)(p−1)/2 = c + d

√x (mod p)

[;[!W

c 6= 0 (mod p)H > >[

:[Y!> >RQ D#> nGd

%1Xp[

& \ )+>_Fn) Lo)+ =L%12p

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P 2 P%12u) P-sc>=P>O(`2)

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W RQT> >a

$ ^QT'*)'Kn) Ko)+ =BxH7)+

(a +√

x)(p−1)/2 D9)+ * E *%1X

p[eq)+ = & >oHI

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dE √

xHn −√x )+!>A]o)oH

9QT-sc> D#>%1>L>AKn) Eo)+ =!x

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aE & >EB D#

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I #F "KE JF ¶I *'F?>1) ) ! "´># CB5) ²Bp

L]!)L e7 & x

] = & *)n)+ & 9H*?)a2 − x = (a +

√x)(a−√x)

[3 >u) K.0*)+ => >KGRQT-A<9n)+QurD# aRQT-A> 95[43#; & 9H_

(a +√

x)(p−1)/2 =c + d

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(a−√x)(p−1)/2 = c− d√

x[

S7`n)+2 & n)+(p−1)/2

EMC>%1cQT> > `oHc+d√

x>

c−d√

xD9)+>V $*)>

* OE * H> > 2 D)+ * a2−x

V = & *)n)+ & 9H2>>E * ^[eq)+ = & >oHc + d

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√x = −c + d

√x

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2d√

xH2

& * %` & & RQTB)d = 0

. >oHX*)+ = & >oHc

D9)+1

−1;-[ ` )+ /o).

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Hc = 0

H>d√

xD9)+

1 −1

H & ^ %` & &

1/d)`( >

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2

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)+ F>%`%19[>LKWXWXL & ^ BJ> "

f HBJIq@ "´>´BJI ) ' dI> #2F

[[1, p− 1]]− √x, p−√x E (a +

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Page 46: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

58

HBJIq@ "´>`BJIf' " > "I # ?> #.@ "´>´BDI #ÇI " !#

[[1, p− 1]]− √x, p−√x # " [[2, p− 2]]

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f(a) = (a − √x).(a +√

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a 6=−√x

%` & & f(a)

( >@=-J H>a 6= √x

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f(a) = 1. >u) = >n) √

x = 0;-H

f(a) = −1. &

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;-[S7J^H

f &"z> D#

[[1, p − 1]] − √x, p −√x *> -s<>oHf(a) = f(b)

%` & /.0*)+ sc=> >l;

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a = b[

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Page 47: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

5 *

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a ∈ [[1, p−1]]I #?I "´> #%TIqBJI I OCB5)¼Bp

¼B FFHBJ> "ar = 1 (mod p)

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Page 48: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

56

Zc]L 2E@> > %`*) n/ TZ'&SL P

* [r ← n

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*) oHNR) r← r/2

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x = 1

x = n− 1H > >

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F> n #F "OE #?C > #% ²B¯F Pr(MR(n) = ) = 1

F> n I #F "E FªE !#?C > #% ¼B ¯F Pr(MR(n) = ) ≥ 3/4

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Page 52: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 53: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 54: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

Ñ ! #""$#% & #'('(*)+, |Ç0¯ÅÄ

Rnz)­ ± ÇLI¬4«+­%²N­ ± ¯ a­+ª-Æn² $ Æ ± ­<zɯÃLÄÊ­BÃ$ª0Æ.Ä Ãª0z)3ª-ľÇ0¯ «+­%²N­ n

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#´­4Ä ¯ zv­0¯ÃLÄÊ­7Æ ± ­fx3Ç ± Ã4ľª ± ÄÊ­ K# ¯ ± ²NÊÈ'­ ± ²pª ± ÄÊ­f²N­ n

# ÄÊ­LzzF­ & Æ ­P(Rn > K log n) = o(1)

xU­ & Æ'­7z%$ Ç ± «3UÃUÆ M­ FN ± 4«ª0zF­M­ ± ÄÈ.ª-«R = O(log n)

ª<a­+x $Ç0«LÄÊ­<Èa«+ÇN¬+ªG¬L¯zɯÅÄÊL! ¦ 10HnHI#4 H$10 79? *76 3#$!$10 :'#MK * HM (+& 10mQlwO? /'( # /'*8( 1 ( 6 #M:'# 6 6)& ( #I#$ (

R =1 + maxx∈S `(x)

,<# (6 #$: &Aµs24* #4 ( `(x)

310 ( :'#$o- *+& > 6 #$P 2 10H 24(+*+&FEN/ #$:'#y9? * H ©4(+* #1/2

,& : 2 9^#4 : ( #$BQIÏ., 9|1 /'*<( 1 /'(

x ∈ S,P(`(x) > m) = (1/2)m , !$# EG/'& #4 (+* & #

P(R ≥ m) ≤ n.(1/2)m Q9^1-5 (

m = α log2 n, &)6 o & #4 (

P(R > α log2 n) ≤ 1

nα−1,

!$# EG/'& HI10 (+* # EN/ # ( 1 /'( #!$10 ( ( #K > 1

!$10No & #4 ( QN\03310 <HM & ( #4? (~86 fHMu1 * (+& 10:'# 6 r ­LþÈ'L«+ª ± xU­f:'# R, EG/'& : 2 !$1 /'6 #: / !B 6 ! /'6 9 *32 ! 2 :'#4 ( Q

#4HM *3EG/ 10 EN/ #-,a9|1 /'*/ #o- *+& > 6 #f 6F2 ( 1 &)* #q#4 (+&F©4* #89^1- &)(+& op#N,?10y

E(N) =∑

m≥0 P(N >m)

QgN1 /'*m ≤ log2(n)

,' 1 / JHMu1 * 10 P(R > m)

9? *1 L # ( ,'9^1 /'* m > log2(n)

, 1 / /'(+&)6)& 310 6 r & 2 PN 6)&)(32

P(R > m) ≤ 1/2m−log2(n) Q /( 1 ( 6 ,' 1 / Bop10 RÅ#4 / 9'9|1-5 ( 9? * # #4Hn9 6 #

n > 2 SE(R) =

k≥0

P(R > k)

≤ log2(n) +∑

m>log2(n)

1

2m−log2(n)

≤ log2(n) +∑

m≥0

1

2m

≤ log2(n) + 2

2

G=1 / 6)6 10 HM & ( #4? (y24(+/ : & # *;6 !$10Hn9 6 # .&)(32 HI1 C #4' #:'# 6 rt109 24* (+& 10 7?^v : / # 6)& ( # ~ 5 /'( q 6F2 ( 1 &)* #-Q ¦ 10HnHI#Zo / 9 *32 ! 2 :'#4HnHI#4 ( , 6 Ï!$10Hn9 6 # &)(32 :'# 7?^v (k, S)

#$ (: 24( # * H & 2 #9? *

R∑

i=1

(1 + f(Ii(k))) = R +R∑

i=1

f(Ii(k))

NMO|Ç0¯ÅÄIÆ ± ¯ ± ÄÊ­L«baª0z z)­f² $ Æ ± ­zɯÃLÄÊ­zBnÃ$ª0Æ.Ä Ã8ª0z)3ª-ľÇ0¯ «+­"!zAÇ0«UÃ8Ç ± ª

E(f(I)) ≤ 2,

Ã4ª-Æ %ÃL¯I = [−∞,+∞[

#´ª0Æ & Æ ­Lzx5ªÃ8Ç ± ªE(f(I)) ≤ 3.

1 &)(I6 r & ( # * o- 6)6 #7!$10 & : 24*32 ,?# (

i + 1310w & op#B / Q1 &)(

y06 f>^1 * # & .Î 24*+& # /'* #7:'#

I,

# ( 31 & #4 (y0, y1, . . . , yk = +∞ 6 #$ 246F2 HI#4 ( :'#

LiR 6 #7 & op#B / ­ ± ° ²N­UÃUÃ4Ç0ÆGÃn:'# I S / HI1 & 2 PN /.

~y0Q

Page 55: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

%)+, CJ)j$ #. ÑM 6 #$ ( ÎÐ0! &)6 #<:'#"op1 &)* EG/ # 6 #´ 10H7> * #:'# 6

f(I):'# 6 r & ( # * o- 6)6 #

I,-#$ (2 PN 6 / 9 6)/ 9^# (+&)(& : & !$#

j( # 6?EG/ #yj ∈ Li+1

QI * ,N!5O?0! / Z:'#J!$#$ 246F2 HI#4 ( 24( ( :'#< & op#B / / HI1 & i9? * !$10 (+*+/ ! (+& 10m, &)6

9 * 10>?> &)6)&)(321/2

:srt (+* #=:'#= & op#B / (+*+& ! ( #4HI#4 ( / 9 24*+& # /'*<~i# ( :'10 !=:sr¶9'9? *+( #4 &)*=~

Li+1 H & ~9? *+(

yk = +∞ , EG/'& #$ ( : Li+1

9? * !$10 (+*+/ ! (+& 10mQgN * !$10 2$EN/ #4 ( ,f(I)

#$ ( : & (+*+& > / 2 !$10HnHI#/ #o0 *+& > 6 #P 2 10H 24(+*+&FEN/ #%:'#J9? * H ©4(+* #

1/2,sx3Ç ± ²-¯ ÄůÐÇ ± ± 5­ ~ (+* #% / 9 6)/ 2 PN 6 # ~

k L 6 rt#$+9 24* !$#:sr / # ( # 6)6 #o0 *+& > 6 # 6F2 ( 1 &)* ##$ ( , EG/ # 6)6 # EG/ #31 &)(86 Ïo- 6 # /'* :'#k,vHMu1 *32 #9? *

2R 6 rt#$+9 24* !$#

:sr / #o- *+& > 6 #P 2 10H 24(+*+&FEG/ #7:'#%9? * H ©4(+* #1/2

10Ï!$10 : &)(+& 10' 2 # S Q¦ # (+( #=? 6)C 3#J:'1 &)( (+* # (+*3© 6F2 P ©4* #4HI#4 ( HI1G: &A?2 #: 6 #d!B0§1I = [−∞,+∞[

RÅ!-rt#$ (@D~@ : &)* # &

I#$ (\6 r / &FEG/ # & ( # * o- 6)6 #d:'#" & op#B /

R S QI# µ # ( ,09 /'& EG/ # R#$ (\6 #"9 * #4H & # * & op#B /M~ #<!$10 ( #4 &)*

/ ! / 246F2 HI#4 ( :'#S,N10Z /'* 9? * !$10 (+*+/ ! (+& 10

f(I) ≥ 2QN !$#J!B0B,

f(I)#$ ( ( 1 / u1 /'* §:'10H & 2

( 1!3O?0 (+&FEG/ #4HI#4 ( 9? *M/ #o- *+& > 6 #;P 2 10H 24(+*+&FEG/ #:'#9? * H ©4(+* #1/2

,§!$10 : &)(+& 10' 2 # ~ (+* # /HI1 & 2 PN 6 # ~

2 L 6 rt#$+9 24* !$#7:sr / # ( # 6)6 #o- *+& > 6 #7 6F2 ( 1 &)* #7#$ ( :'# 3Q

2

|Ç0¯ÅÄSÆ ± ­7zɯ Ã4ÄÊ­zBnÃ$ª0ÆÄ Ã7ª0zF+ª-ľÇ-¯«3­n²N­7ľª0¯ zzF­ n

# ­$ÄkÆ ± ­fx4zF"!

z)Ç0«UÃ%zF­fx3Ç.Ä nÇLIp­ ± ²N­7z%$ ÇLÈ'L«+ª-ÄůÅÇ ± 8?^v (k, S)­UÃLÄ

O(log n)!

G1 / 5$op10 : 2 u ~qEG/ # 6 fO? /'( # /'* :'# 6 r¶ * > * ##$ ( , #4;HI1 C #4' #7# ( Bop#$!%ÎÐ1 *+( #9 * 10>? @> &)6)&)(32 ,

O(log n),s# (EG/ #q!3O? EG/ #I310HnHI# ( : / !3O #4H & :'# * #$!3O # * !3O #:'#

k / Ì 10H7> * #I#$39 24*32 :'#

6 O(1)

Qlm# *32 /'6)( ( 9 *32 o / #§: 2 !$1 /'6 #"9?0\3# /'6 #4HI#4 ( : /f*32 /'6)( ( /'*v6 O? /'( # /'* HI1 C #4' # L 1 / Bop10 *32 # 6)6 #4HI#4 ( >|#$51 & q: /q*32 /'6)( ( :'# ÎÐ1 *+( #"9 * 10>?> &)6)&)(32 R 6 %!$10Hn9 6 # .&)(32 Brt# 9 *+& HI#<!$10HnHI#<310HnHI#<:sr /

10H7> * # 6F2 ( 1 &)* #:'#o0 *+& > 6 #$< 6F2 ( 1 &)* #$<:'10 ( 1 / §mr¶$op10 EG/ r / #=HMu1 * (+& 10:'#$´#$+9 24* !$#$ L10Ì #n9^# /'( 9?0: 2 : /'&)* #I:'# ( # 6)6 #$O C 9|1 ( O © 3#$ EN/ # 6 rt#$39 24* !$#I:'# 6 w510HnHI#I31 &)( ,^9? * # #4Hn9 6 #-,HMu+1 *32 #9? *d6 #%9 * 1: /'&)( :'#$d#$+9 24* !$#$ S Q1 &)(

Yi6 #´ 10H7> * #<:sr & ( # * o- 6)6 #$o & &)(32 ~ O? /'( # /'*

i:'# 6 r¶ * > * # L 10qU &)(EG/ # 6 rt10I E(Yi) ≤ 2

,0# (Yi ≤ n

Q 1 &)( 2 PN 6 #4HI#4 (Y =

i Yi6 #" 10H8> * # ( 1 ( 6 :sr & ( # * o- 6)6 #$ o & &)(32 / !$1 /'* :'# 6 * #$!3O # * !3O #-Q

G=1 / J$op10

E(Y ) =+∞∑

i=0

E(Yi)

=

+∞∑

i=0

E(Yi|Yi ≥ 1)P(Yi ≥ 1)

=

+∞∑

i=0

E(Yi|Yi ≥ 1)P(R ≥ i)

≤+∞∑

i=0

2P(R ≥ i)

≤ 2 log2(n) + 2∑

i>log2(n)

n

2i

≤ 2 log2(n) + 4

Uf p lf neponlm nqm,n p X f! p f"=r# $&%ln r# ep'" (*f) lf=n* + Y , r pm f#n P(X ≥ x) ≤ P(Y ≥ x)- !. ! x )/4mEr n k p 01 :f"2 mon epbf3 f +m rJy4qw t5 X 6 7 Y , 6 7):p r# 7):pbnqm'*f) 08m9 n:; n epbfr+lp n f sp m6< p r# , ln f:r0:f=$6+ 8nqp f> r - n$ - *En*:p mop? r , <3 neponlm r X ′ 6 Y ′ , @ (A ( rmbp r0*r - $6 epB r0" X 6

Y , 6 7 *mom r0" m bfn p? - n+ * X ≥ Y "CDbp m'8 , B!:r - !"!EF!lm p65$6 + Jf* epbf> m') - 36<* ep'"b*

Page 56: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

Ò ! #""$#% & #'('(*)+,RvN1 /'* K * HI# *EN/ # 6 rt10®

E(Yi|Yi ≥ 1) ≤ 2, &)6 / K ( :'# * #4HM *3EN/ # *EG/ #

Yi#$ ( / 9 6)/ 2 PN 6

/ 10H7> * #:'# 6 <: / :'# * & # *d& ( # * o0 6)6 ## H & 2~ O? /'( # /'*i + 1 L !-rt#$ ( :'10 !-,': ( 1 / 6 #$<!B0,/ #8o0 *+& > 6 #n 6F2 ( 1 &)* #q ( 1!3O?0 (+&FEG/ #4HI#4 ( :'10H & 2 #f9? *=/ #7o- *+& > 6 #fP 2 10H 24(+*+&FEN/ #q:'#89? * H ©4(+* #

1/2Q S 2

J¬4ÄÊ­ ± ¯ «<Æ ± ­ Iª B$Ç0«+ª-ÄůÅÇ ± ÈazÉÆNÃE ± ­d²N­dzAªfx3ÇDÈazF­0¯ÅÄÊCIÇDIN­ ± ± ­J²N­ 8?^v (x, S)#

­ ± x3ª0z)x4ÆzAª ± Ä#?È'Ç0ÆG«%²N­LÆ f¯ ± ²0¯ÅxU­Uà i­4Ä

j#z)ªdÈa«ÇG¬+ªN¬L¯ z ¯ÅÄÊ & Æ ­=z%$ ¯ ± ÄÊ­L«baª0z zF­ [xi, xj [

Ã4Ç-¯ ÄjaB¯ ÃL¯ ÄÊB8³ª-ÆÄÊ­LÆ«`²N­8z%$ ª0«$¬4«+­"! ­4ÄÐÄÊ­JÈ|«ÇN¬3ªN¬L¯ z ¯ÅÄÊÈ'­4ÆÄ´Ã $ ­LÈa«U¯M­L«I­pªpx$ÄÊ­ I­ ± Ä­ ± $Ç ± x$ÄůÐÇ ± ²N­

i#j#`­4Ä<²N­fz%$ ¯ ± ²-¯Åx5­

k²N E ± ¯|È.ª0«

k = maxi : xi ≤ x& Ư «3­ÊÈa«3UÃ$­ ± ÄÊ­fzAªÈ.ÇÃL¯ ÄůÐÇ ± Çà $ ¯ ± Ã4«+­L«+ª0¯ÅÄ Æ ± Lz) I­ ± Ä´²G­8x$z) x

!M 6 3# * &)( 9^1-3 & > 6 #:'#9^1 / 33# *</ 9^# / 9 6)/ 6 r¶? 6)C 3#9^1 /'* 10> ( #4 &)*J/ 9^# / 9 6)/ ­ ± IÇDIN­ ±?± ­­4Ä"ªEa­+x 4Ç0«4ÄÊ­<Èa«+ÇN¬+ªN¬L¯ zɯ ÄÊ #´z($ ÇUÈ'4«ª-ÄůÐÇ ± 7?^v ÃLÆG«Æ ± ­8zɯ Ã4ÄÊ­zBnÃ$ª0ÆÄ Ã8ª-z)+ªpľÇ0¯«3­n²N­8ľª0¯ z z)­ n

ªZÆ ±x3Ç.ÄO(log n)

Qlm#7HI4HI# (DC 9^#:sr¶? 6)C 3#9^# /'( (+* #89'9 6)&FEG/ 2 /. 109 24* (+& 10 5m s? # ( 8'ss? ,a$op#$! 6 #HI4HI# (DC 9^#<:'# *32 /'6)( ( -!$#$ :'# /. 109 24* (+& 10 B,p#4nHI1 C #4' #J# ( Bop#$!"ÎÐ1 *+( #"9 * 10>?> &)6)&)(32 ,G10 ( / I!$1 (

O(log n)Q

R%S [|k]dWfeM 6 #$ ( : & KM! &)6 #%:'#:'10' # *"/ # (+* 0: / ! (+& 10Î * HB & 5#5 (+& +ÎÐ & 5 ( #%: / HI1 (@ o- 6)& 3#fÄÅ«+­+ªLÈ|,ÎÅ1 * H 2%~

9? *+(+&)* :'#MÄÅ«+­3­f# ( :'#q³.­+ªUÈ L / (+* #B9#$ (<6 n!$100u+10 ! (+& 10Ï:sr / * > * #> & ? &)* #7:'# * #$!5O # * !3O #f# ( :sr / ( 0B,'# ( ÎÐ1 /'* &)(J2 PN 6 #4HI#4 (J/ #31 6)/'(+& 10Ï#LKM!B0!$#7 / 9 * 10> 6F© HI#:'# (+*+/ ! (+/'* (+& 10Ï:'#:'10' 2 #$BQ2/.8. 9L=A 9 A,=; 6 ; 9L= ;=@ ;

9'9|# 6 10 * 9 & :'#4HI#4 (=EG/ # 6FEG/ #$d: 2L &)(+& 10 7 / / ¨ * > * #w> & ? &)* #:'10 ( !5O? EN/ #310HnHI# (n& ( # * #

u#$ (n24(+&FEG/ # (32

9? *"/ #%! 6F2k(u)

R 6 #$"! 6F2 B,.: & (+& ! ( #$B,.310 ("& 3 / #$´:sr / #4 3#4H8> 6 # ( 1 ( 6 #4HI#4 ( 1 * :'10' 2 S ,'#$ (/ ª0«$¬4«+­n¬L¯ ± ª0¯ «3­7²N­7«3­+xL³.­4«xL³'­n & ,.9^1 /'* !3O? EG/ #310HnHI# (J& ( # * # v,

&u#$ (</ 510HnHI# ( : / 31 / @ * > * #PN / !5O # & 3 / :'#

v,k(u) < k(v) L /

w#$ (</ ;510HnHI# ( : / 31 / @ * > * #7: * 1 &)(d& 3 / :'#

v,k(v) < k(w)

Ql#9? * !$1 /'* J C H 24(+*+&FEG/ #:'#$d310HnHI# ( & ( # * #$B,.ÎÐ1 /'* &)(d6 #$d! 6F2 J: 6 rt1 * : * #! * 1 & 3U ( Q

/ I * > * #§> & ? &)* #-,N:'10 ( !3O? EG/ #<310HnHI# (& ( # * #u#$ (24(+&FEN/ # (32 9? */ #"! 6F2

k(u),-#$ (

/ wľªÃd¬L¯ ± ª0¯«3­" & ,9^1 /'* !5O? EN/ #´310HnHI# ( u /'(+* # EG/ # 6 * 0! & #-,0:'# 9 ©4* #

v,10n

k(v) < k(u) Q ÄÅ«3­+ªUȨ#$ (8/ * > * #Z> & ? &)* #M:'10 ( !3O? EG/ #310HnHI# (7& ( # * #ZHM & (+& #4 ( :'# /.®& .ÎÐ1 * HM (+& 10 ªnÈa«U¯ÐÇ0«L¯: & (+& ! ( #$Z / #x4zF

k(u),# (/ #qÈa«U¯ÐÇ0«L¯ ÄÊ

p(u) L 6 #$7! 6F2 ÎÐ1 * HI#4 (7/ * > * #n> & ? &)* #M:'#* #$!3O # * !5O #-,a# (<6 #$d9 *+& 1 *+&)(32 B, / ( 0<> & ? &)* #-Q |Ç0¯ÅÄ

S ⊂ K × PÆ ± ­ ± ÃB­M¬Lz)­E ± ¯d²N­Mx5Ç0ÆBÈ|z)­UÃ

(ki, pi)#ÇÌzF­Uí ± Ã$­M¬LzF­UÃ

K­4ÄP

­ ± ÃB­M¬Lz)­LòN­LÃx4zFUí4IJN­UÃ8Èa«L¯ÅÇ-«U¯ÅÄÊUÃQ#%«3­UþÈ'­3x$Äů4a0­M­ ± Ä ÌÃ4Ç ± ÄľÇ-ľª0zF­M­ ± Ä7Ç-«²pÇ ± ± Uà #­4Ä7ÄÊ­Lz Ã& Æ ­qľÇ0ÆGÃ7zF­Uà ki

­4Ä"ľÇ0ÆGÃ7z)­LÃpi

Ã$Ç0¯¾­ ± Ä<²0¯ÃLÄů ± x$Ä Ã ! Uz­0¯ÃLÄÊ­8Æ ± Æ ± ¯ & Æ ­qÄÅ«3­+ªUȹ²NÇ ± Ä´z)­LÃÃ4ÇD M­4Ä ÃÃ$Ç ± Ä4Äů & Æ ­4ÄÊUÃ<È.ª-«z)­LÃfLz) I­ ± Ä Ã8²N­ S!

V fJf$6bflr+&B - n r , =mon5"!lflp? epbf@$ monqr r p .F 8nqr fF 8nqf) "gr# +"$6 Dbf:f" , mon5$ f p ep f 1 lp m p'lp1B , f - n+ ep$lm p6 , ) ! r+m r # :pom m r m nJr+bp? FF (A ( - $# bf" 8 1 - &% r

Page 57: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

# Ò P a 2 HI10 (+* 10 d9? *´*32 ! /'*+* #4 !$#% /'*

n = |S| 6 9 * 109 *+&F24(32 Q N1 /'* n = 0, 6 79 * 109 *+&F24(32 #$ (

(+*+& o & 6 #I &)6 # .& ( # / / &FEN/ #8 * > * #> & ? &)* #!$10Hn9 6 # ( U d310HnHI# (d& ( # * #-Q / 9'9^1-310 w:'10 ! 6 9 * 109 *+&F24(32 RÅ:srt# & ( #4 !$#Ï# ( :sr / & ! &)(32 S o * & #9|1 /'*( 1 /'(

m ≤ n,§# ( 51 &)(

S/ h#4 3#4H8> 6 #:'# ( &)6)6 #

n + 1Q 1 &)(

(k, p)6 r 246F2 HI#4 ( :'#

S:'#Ì9 *+& 1 *+&)(32 H & & HM 6 #-,J# ( 31 & #4 (

S< = (k′, p′) : k′ < k # ( S> = (k′, p′) : k′ > k L !$#$:'# /. #4 3#4H8> 6 #$310 ( :'# ( &)6)6 #f / 9 6)/ n,'# ( 0:.HI# (+( #4 ( :'10 !!3O?0! / / / &FEN/ # (+* #B9mQM 6 #$ (& HnH 2 : & ( :'#no 24*+&A # *fEN/ # 6 r¶ * > * #I> & ? &)* #M:'10 (76 * 0! & #M#$ (724(+&FEG/ # (32 #

(k, p),:'10 (86 #

31 / @ * > * #PN / !5O #Ì#$ (Z6 # (+* #B9X:'#S<

# (w6 #Ï51 / @ * > * #y: * 1 &)( #$ (Z6 # (+* #B9X:'#S>

,§o 24*+&A # 6 #$9 * 109 *+&F24(32 f:sr¶ * > * #I> & ? &)* #M:'# * #$!3O # * !5O # R 9^1 /'*76 #$8! 6F2 S # ( :'# ( 07> & ? &)* # R 9^1 /'*76 #$79 *+& 1 *+&)(32 S L!-rt#$ ( :'10 !q> & #4 / (+* #B9Ì9^1 /'*

SQs%#f9 6)/ B, 6 9 * 109 *+&F24(32 :'# ( 0> & ? &)* # & Hn9 6)&FEG/ # EG/ # 6 * 0! & #

²pÇ0¯ÅÄJBop1 &)*=6 M9 6)/ =9|# (+&)( #q:'#$=9 *+& 1 *+&)(32 q?9? * !$10 2$EG/ #4 ( ,^: ( 1 /'(=(+* #B99^1 /'*S, 6 * 0! & #q#$ (

24(+&FEG/ # (32 #(k, p)

Q?lq9 * 109 *+&F24(32 :sr¶ * > * #> & ? &)* #7:'# * #$!3O # * !3O # & Hn9 6)&FEG/ #7 6 1 * EG/ # 6 #$d! 6F2 d: / 31 / @ * > * #PN / !5O # #9^# / op#4 ( (+* # EG/ #!$# 6)6 #$ EG/'& 310 (d& .Î 24*+& # /'* #$ ~

k, # ( !$# 6)6 #$=: / 31 / @ * > * #7: * 1 &)( ,

!$# 6)6 #$ EN/'& 310 ( / 9 24*+& # /'* #$ ~k L 9? * !$10 2$EG/ #4 ( , 6 #f31 / @ * > * #8PN / !3O #q:'1 &)( (+* # / (+* #B9y9^1 /'*

S<,-# (6 #<31 / @ * > * #<: * 1 &)( , / (+* #B9I9|1 /'*

S>,-!$# EG/'&'& Hn9 6)&FEN/ # EN/ # 6 # (+* #B9n9^1 /'*

S#$ ( 2 PN 6 #4HI#4 (

/ &FEG/ #-Q2

l rt109 24* (+& 10! 6 03 &FEG/ # 8?^v R 9^1 *+( ( /'*§6 #$´! 6F2 S #$ (´*32 6)& 2 #= /'*§/ (+* #B9w:'# 6 7HI4HI#HM &F©4* # EG/ # /'*</ * > * #7> & ? &)* #:'# * #$!3O # * !5O #-Q

l rt109 24* (+& 10 5m s? (k, p, S)#$ (s& Hn9 6F2 HI#4 (32 #§#4!$10HnHI#4 HB ( 9? * # µ #$! (+/ # */ 7?^v (k, S)

,9 /'& <#4u+1 /'( (<6 #% 1 / op#B / 310HnHI# (<& ( # * # ~86 f9 6 0!$#:'# 6 7ÎÐ# /'&)6)6 #1 6 * #$!3O # * !3O #83# ( # * H & #9? *w/ 2 !5O #$!-QM 6 #$ ( > & #4 #4 ( #4 : / 9|1-5 & > 6 # EG/ # 6 !$10 : &)(+& 10X:'# ( 0w31 &)( 6 1 * Zo & 1 6F2 # L !$# (+( #!$10 : &)(+& 10y3# * *32 9? *32 #f#4Ï# µ #$! (+/ (=/ # * 1 ( (+& 10Ï#4 (+* # 6 #7 1 / op#B / 310HnHI# ( # ( 3109 ©4* #-,a# ( #4* #$!$10HnHI#4 HB ( #4 * #4HI10 ( ( op# * 6 * 0! & # ( (EG/ # 6 #§310HnHI# (v* #4HI10 (32 / #§9 *+& 1 *+&)(32 & .Î 24*+& # /'* #~ !$# 6)6 #:'#5109 ©4* #-Q

m, 8'ss (k, S)3#7ÎÐ &)( #4y# µ #$! (+/ (=/ # * 1 ( (+& 10Ì#4 (+* # 6 #f310HnHI# ( :'#8! 6F2

k# ( !$# 6)/'&

:'#q3#$ 6 EN/'& 6 Z9 6)/ 9^# (+&)( #q9 *+& 1 *+&)(32 L !$# (+( #q109 24* (+& 10®#$ (*32 9 24(32 #=u / EN/ r ~ !$# EN/ # 6 #q310HnHI# (:'#! 6F2

k &)( :'# /. ÎÐ# /'&)6)6 #$J!$10HnHI# 6 B,? / EG/ # 6 !B0J109|# /'( & Hn9 6 #4HI#4 (246)& H & # *6 #310HnHI# ( # (d6 #

* #4Hn9 6 0!$# * 9? *J/ #=ÎÅ# /'&)6)6 #-Q¦§6 &)* #4HI#4 ( ,?!3O?0! / #7:'#$<109 24* (+& 10 d:'# * #$!5O # * !3O #7# ( :'#=H & 3# ~ u+1 /'* r & Hn9 6F2 HI#4 ( ##4 ( #4Hn9

O(h),?1

h: 2 & P- # 6 nO? /'( # /'*d( 1 ( 6 #:'# 6 r¶ * > * #> & ? &)* #-Q

2/.8.21 354/687:9e;<;>=4? @@?#6A986.7:9E; 6; 9L= ;g@@;7N1 /'* 10> ( #4 &)* / nHI1: ©46 #"9 * 10>?> &)6)& ( #d:'# (+* #B9 B, &)6 1 / \ξ /'( 9 *32 ! & 3# * !$10HnHI#4 ( , ~ 9? *+(+&)* :sr /

#4 3#4H8> 6 #7:'#! 6F2 B, !5O 1 & &)* :'#$d!$1 / 9 6 #$:'#! 6F2 d# ( :'#9 *+& 1 *+&)(32 Q #n31 6)/'(+& 10® & Hn9 6 #n# ( 5 (+& +ÎÐ & 5 ( #n#$ (%6 w /'& o- ( # 6 Z9 *+& 1 *+&)(32 0331! &F2 # ~/ ®10>.u# (EG/ # 6A@

!$10 EG/ ##$ (n/ #wo0 *+& > 6 #Ï 6F2 ( 1 &)* # / & ÎÅ1 * HI# /'*[0, 1]

, & : 2 9^#4 : ( #Ï:'#$M /'(+* #$RÅ# ( :'# 6 y! 6F20331! &F2 # S Q ¦ # (+( #w9 *+& 1 *+&)(32 #$ (f'.2 # 6 1 * n:'# 6 r & 3# *+(+& 10m,# ( mrt#$ ( 9?0qHI1: &A?2 # ( (IEG/ # 6 rt10>.u+# (* #$ ( #: 6 r¶ * > * #-Q

o * & : &)* #-, &)6 mrt#$ ( 9?0\#$33#4 (+& # 6EG/ # 6 #$9 *+& 1 *+&)(32 \ /'& op#4 (/ # 6 1 &/ & ÎÅ1 * HI# L 6 J5# /'6 #§!5O 1-3# EG/'& 1 / & (324* #$35# & ! & #$ (vEG/ #n9 *+& 1 *+&)(32 31 & #4 (( 1 /'( #$\: & (+& ! ( #$$op#$!´9 * 10>?> &)6)&)(32

1,# (EN/ rt# 6)6 #$\31 & #4 (

1 * :'10' 2 #$7 /'& o0 (/ #q9|# * H /'( (+& 10 6F2 ( 1 &)* # / & ÎÐ1 * HI#I:'#n246F2 HI#4 ( BQ ®!$#n3#4 B,^mr & Hn9^1 *+( #

EG/ # 6)6 # 6 1 & : &Aµ|/ 5#!$10No & #4 : * &)( L 6 6 1 &m/ & ÎÐ1 * HI##$ ( 5# /'6 #4HI#4 (J6 n9 6)/ d & Hn9 6 #

=* !$# ~M6 I9 * 109 *+&F24(32 :sr / & ! &)(32 , 6 # (+* #B9y10> ( #4 / 9 *3© / #f /'&)( #8:sr & 5# *+(+& 10 =# ( :'#f:'#$ (+*+/ ! @(+& 10 q #: 2 9|#4 : EG/ #Z:'#$ (+&)* Pp#$I 6F2 ( 1 &)* #$n:'#$f9 *+& 1 *+&)(32 I:'#$q10>.u+# ( EG/'& «+­UÃ4ÄÊ­ ± Äf: 6 r¶ * > * #-,# ( 109?0B,a & :'# 6 rt1 * : * #8:'#f!$#$ & 3# *+(+& 10 B,a & :'#$ 2 op#4 (+/ # 6 10>.u+# ( EG/'& 10 (24(32* # (+&)*32 =9|1 /'* #

Page 58: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

ÒL ! #""$#% & #'('(*)+,9?0J (+* # *324& 24*32 BQ Ï9? *+(+& ! /'6)& # * , 6 # (+* #B910> ( #4 / #$ ( ¯Ð²N­ ± Äů & Æ ­ ~ !$# 6)/'&vEG/ # 6 rt10 /'* &)( 10> ( #4 /#4 & 24* (6 #$! 6F2 : 6 rt1 * : * #n! * 1 & 55 ( :'#$=9 *+& 1 *+&)(32 EG/'&\6 # /'* 10 (24(32 03 & P- 2 #$BQ^ !$# (+( # &)(+/ (+& 10m, / ! / # * 1 ( (+& 10mr¶ 6)& # / 6 r & 3# *+(+& 10 5#qÎÐ &)( # 0! ( #4HI#4 ( !$10HnHI#Z: / * > * #Z> &A@? &)* #:'# * #$!3O # * !5O #-Q ¦ # (+( #%9 * 109 *+&F24(32 #$ ( #$33#4 (+& # 6)6 #4HI#4 (J6 fHI4HI# EG/ #!$# 6)6 # EG/ #% 1 / d$op10 J: 2 u ~HI#4 (+& 10' 2 #$9^1 /'*d6 #$d & 9 6)& ( B,'# ( 9 *32 3#4 ( # 6 #$<HI4HI#$=$o- ( Pp#$BQ

ÎÐ &)( ,?9? * !$# EG/ # 6 #$d9 *+& 1 *+&)(32 %310 ( !3O 1 & & #$ & : 2 9^#4 :'#4HnHI#4 ( :'#$! 6F2 B, 6 # (+* #B910> ( #4 / ,| &6 rt10f # * # (+& #4 (\EG/ # 6 #$! 6F2 ,mrt#$ (v*+& #4n:sr¶ /'(+* # EG/ r / I * > * # > & ? &)* #< 6F2 ( 1 &)* #iRÐ * > * #´> & ? &)* #§10> ( #4 /#4 & 24* (J6 #$! 6F2 d: / 1 * : * #f 6F2 ( 1 &)* #-, ( 1 /'( #$ 6 #$d9^# * H /'( (+& 10 24( (2$EG/'& 9 * 10>?> 6 #$ S Q9? *+(+& ! /'6)& # * , ( 1 /'( #P * :'# /'* 9 * 10>?> &)6)& ( #!B 6 ! /'6F2 #w /'*f6 #$I * > * #$8> & ? &)* #$I 6F2 ( 1 &)* #$,\9|# /'( (+* #(+* +9^1- 2 # ~ 1 (+* #HI1: ©46 #:'# (+* #B9 BQ2/.8.43 @AJ9<;=A8= 6 ;=7 @@=?>= ;=7 ?6 @6 = ;=7 6 ;<= ; ; = ; @@9g@ 9L4j6 = ; 7

6 #J!B0 EG/'& 1 / & (324* #$53#-, 6 #J!$1 ( :sr / # & 3# *+(+& 10#$ ( HMu1 *32 9? * 6 O? /'( # /'* :'# 6 r¶ * > * #-,EG/'& #$ ( :'10 ! 6 fP * :'# /'*JEG/ #% 1 / d:'#4op10 J? 6)C 3# * Q 33#4 (+& # 6)6 #4HI#4 ( ,a 1 / J 6)6 10 d: 2 HI10 (+* # *J6 #( O 2 1 *3© HI#7 /'& o0 ( @ ª8³ª0Æ.ÄÊ­LÆG«

hn² $ Æ ± ª0«B¬L«+­7¬L¯ ± ª0¯«3­%²N­«3­+xL³.­4«xL³'­7ª0zF+ª-ľÇ-¯«3­²N­ n

Ã4ÇD M­4Ä ÃQ#aL«L¯ E´­E(hn) = O(log n)

M 6 # .& ( #79 6)/ & # /'* =H 24( O 1G:'#$: &Aµs24* #4 ( #$=9^1 /'* 9 * 1 / op# * !$# ( O 2 1 *3© HI# L !$# 6)6 # EG/'& #$ ( 9 *32 3#4 (32 #& ! & #$ ( #$53#4 (+& # 6)6 #4HI#4 ( !$# 6)6 #9 * 109^1- 2 #: ÊQlm# 6 #4HnHI#7Ò.Q f 1 / "ÎÐ1 /'* &)(d/ #:'#$3! *+& 9 (+& 10# 9 6)& ! &)( #-, #4wÎÐ10 ! (+& 10:'# 6 rt1 * : * #:sr & 5# *+(+& 10:'#$

! 6F2 B,':'#$= !$ (+* #$J:sr / #! 6F2 : / * > * #> & ? &)* #7:'# * #$!5O # * !3O #-Q, @ |Ç0¯ÅÄ

σÆ ± ­È'­L«fÆ.ľª-ÄůÐÇ ± ²N­LÃ

n­ ± ÄůЭ4«5à 1, . . . , n

#%­4ÄÃ$Ç0¯ ÄT

z%$ ª0«B¬L«3­¬L¯ ± ª0¯«3­²N­Z«3­L°xL³.­4«xL³'­nÇN¬4ÄÊ­ ± Æ­ ± ¯ ± Ã$L«+ª ± Ä z)­UÃf­ ± ÄůЭ4«5Ã7²pª ± Ã%z%$ Ç0«²-«+­ σ1, . . . , σn

!z)Ç0«UÃQ#^È.Ç0Æ«

i < j#σi

­UÃLÄ Æ ± ª ± xQ)4ÄÅ«3­q²N­ σjÃU¯ ­4Ä Ã$­LÆzF­M­ ± ħÃU¯

σi = min k` : 1 ≤ ` ≤ i­$Ä

σ` > σjÇ0Æ

σi = max k` : 1 ≤ ` ≤ i­4Ä

σ` < σjRÅ#4:sr¶ /'(+* #$ ( # * HI#$B, 6

i@Ê© HI#7! 6F2& 24*32 #7:'#4o & #4 (/ !$ (+* #7:'# 6

j@Ê© HI#8 & # ( 5# /'6 #4HI#4 ( &

/ ! / #! 6F2 !$10Hn9 *+& 5##4 (+* #8# 6)6 #$<mr¶ 24(32%& 24*32 #7Bo0 (J6 i@Ê© HI# S 1 &)(

Ti6 r¶ * > * #10> ( #4 / #4Zmr & 24* ("EG/ # 6 #$§! 6F2

σ1, . . . , σiQ &

σi#$ ( / !$ (+* #=:'#

σj,. 6 1 * , 6 1 * <:'#%310 & 3# *+(+& 10;:

Tj−1, 6 f! 6F2

σj /'&)("6 #%!3O #4H & :'# 6 * 0! & # ~

σiQ ¦ #%!5O #4H &

#$ ( # 0! ( #4HI#4 ( !$# 6)/'& EN/ r &)6 /'* &)( /'& o & : Ti L 9? * !$10 2$EG/ #4 ( ,m & σj

24( &)(& 24*32 : Ti, &)6

3# * # (+* 1 / op# * &)( !$10HnHI# 6 7:'#σiQjI * ,s: / * > * #n> & ? &)* #n:'# * #$!3O # * !5O #-, / #fÎÐ# /'&)6)6 #n#$ ( 31 &)(

6 89 6)/ "P * :'#! 6F2%EN/'& 31 &)("& .Î 24*+& # /'* # ~ 510Z9 ©4* #CRÅ & !-rt#$ ("/ #=ÎÅ# /'&)6)6 #=PN / !3O # S ,?31 &)(§6 f9 6)/ ´9^# (+&)( #EG/'& 31 &)( / 9 24*+& # /'* # ~ 3109 ©4* #!RÅ & !-rt#$ (d/ #ÎÅ# /'&)6)6 #: * 1 &)( # S Q / 9'9^1-310 =HM & ( #4? (EN/ #σi

31 &)(=6 n9 6)/ =9^# (+&)( #7! 6F2 ,a9? * H &v6 #$i9 * #4H &F©4* #$, EG/'& 51 &)( / 9 2L@

*+& # /'* # ~σj

R 6 r¶ /'(+* #f!B0B, 1σi

#$ (d6 q9 6)/ JP * :'# EG/'& 31 &)(d& .Î 24*+& # /'* # ~σj,?3# (+* &)( #7:'# 6 qHI4HI#

HM &F©4* # S Q 6 1 * B, 6 1 * %:'# 6 r & 3# *+(+& 10®:'#σj, &)6 #$ (& : & 5!$# * ?> 6 #n:'#

σi( (EG/ rt10 # 6 #q!$10Hn9? * #

EG/ r ~ :'#$ ! 6F2 & 24*32 #$§Bo0 (σi

@ !$# EN/'& #$ (6 #d!B0 :'# ( 1 /'( #$ 6 #$ ! 6F2 EN/'& 5# (+* 1 / op#4 ( /'* 6 #d!5O #4H & :'# 6 * 0! & # ~

σiQ N\ * !$10 2$EN/ #4 ( ,

σj /'& o * 6 #fHI4HI#n!3O #4H & EG/ #

σi6 1 * :'#q310 & 3# *+(+& 10m,s# (

3# * q:'10 ! & 24*32 !$10HnHI#:'#$3!$#4 : ( :'#σiQ

2

Page 59: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

# ÒN1 /'*J/ #! 6F2

s = σj,'9? *+(+&)(+& 10' 10 6 rt#4 3#4H8> 6 #8:'#3#$ !$ (+* #$#4 Ë !$ (+* #$JPN / !3O #$Í RÅ!$# /.

EG/'& 310 ( / 9 24*+& # /'* ~s,0:'10 (

s9'9? *+(+& #4 ( / 31 / @ * > * #dPN / !3O # S # ( Ë !$ (+* #$ : * 1 &)( Í&R & .Î 24*+& # /'* ~

s S Ls = σi : i < j, σi ≤ σj, σi = maxσ` : ` ≤ i, σ` ≤ σjRs = σi : i < j, σi ≥ σj, σi = minσ` : ` ≤ i, σ` ≥ σj

N1 /'*r < s

,r ∈ Rs

& # ( 5# /'6 #4HI#4 ( &?6 8! 6F2r#$ (§& 24*32 Bo0 ( !5O?0! / #:'#$§! 6F2

r +1, . . . , s L6 rt1 * : * #=:sr & 3# *+(+& 10 24( ( 6F2 ( 1 &)* #-,!$# (§2 o 2 #4HI#4 ( 3#d9 * 1: /'&)( Bop#$!J9 * 10>?> &)6)&)(32 1s−r+1

QG=#JHI4HI#-,9^1 /'*

r > s,r ∈ Ls

& # ( 3# /'6 #4HI#4 ( &r#$ ( & 24*32 Bo0 ( !3O?0! / #%:'#$"! 6F2

s, s+1, . . . , r− 1,G31 &)(

$op#$!9 * 10>?> &)6)&)(32 1r−s+1

QÏ!$10 2$EN/ #4 !$#-,?10Ï

E (|Rs|) = Hs − 1

E (|Ls|) = Hn−s+1 − 1

I#4;: 2 : /'&)(=EN/ # 6 #% 10H8> * #As = |Rs|+ |Ls|

:sr¶ !$ (+* #$J:'#s,.o 24*+&A #

E(As) = Hs + Hn−s+1 − 2 ≤ 2 ln(n) + O(1).

v1 /'( #LÎÅ1 & B,^!$#f & Hn9 6 #f!B 6 ! /'6 :srt#$39 24* !$#f #89|# * HI# ( 9?0%:'#8!$10 ! 6)/'* # EG/ (~I6 rt#$39 24* !$#q:'#6 O? /'( # /'* :sr / * > * #M> & ? &)* #w:'# * #$!3O # * !3O #Ìv#4 # µ # ( , 6 O? /'( # /'* :'# 6 r¶ * > * ##$ (f6 # Iª 0¯qÆ:'#$

As, 6 #$ EN/ # 6 8 #w310 ( 9?0q: /( 1 /'(q& : 2 9^#4 : ( BQJN1 /'* K * HI# *f/ # & 2 PN 6)&)(32 :'# 6 ;ÎÐ1 * HI#

P(h ≤ k) < ε, &)6 1 / <ÎÐ / : * &)("/ # & 2 PN 6)&)(32 : /(ÊC 9^#

P(As ≤ k) < εn L 1 * , 6 r & 2 PN 6)&)(32 :'#y * p1BoR 6 q3# /'6 #9'9 6)& !B> 6 # &s6 rt10mr¶ & Æ'­ 6 rt#$+9 24* !$# S #% 1 / d:'10' # * &)(d/ # ( # 6)6 # & 2 PN 6)&)(32EN/ #%9^1 /'*:'#$<o- 6 # /'* J:'#

k> & #4 / 9 24*+& # /'* #$ ~

lnnQN1 /'* 10> ( #4 &)*f/ # & 2 PN 6)&)(32 9 6)/ f9 *32 ! & 3#-, 1 / q:'#4op10 f 1 / & (324* #$35# *n~6 Ìz)Ç0¯%²N­7Èa«+ÇN¬+ªN¬4¯°

zɯ ÄÊZ:'# |Rs|R 6 r¶? 6)C 3#M#$ ( #$33#4 (+& # 6)6 #4HI#4 (q6 wHI4HI#M9|1 /'*

Ls S Q ¦§6 &)* #4HI#4 ( , Rs #I: 2 9^#4 : EG/ #

:'# 6 rt1 * : * #:sr & 3# *+(+& 10¹:'#$7! 6F2 1, . . . , s

R 6 #$8! 6F2 8 / 9 24*+& # /'* #$8mr & ( # * o & #4' #4 ( 9?0 S Qvlo- *+& > 6 # 6F2 ( 1 &)* #

1 + |Rs|R 6 #

+19 * 1o & #4 ( :'#

s, EN/'& mrt#$ ( 9?0=9 *+& #4Ì!$10Hn9 ( #f:

Rs S #$ (%6 #7 10H8> * #:'#n«3­+x3Ç0«+²Ã%R 246F2 HI#4 ( 9 6)/ <P * :' EG/ # ( 1 / J!$# /.EN/'&s6 #$10 ( 9 *32 ! 2 : 2 S : 6 q /'&)( #7:sr & 3# *+(+& 10:'#$ 246F2 HI#4 ( 1~

sQI * , 6 y9 * 10>?> &)6)&)(32 9^1 /'*I6

k@Ê© HI# & 5# *+(+& 10 :'#;!$10 (+&)(+/ # *Z/ * #$!$1 * :¨#$ (

# 0! ( #4HI#4 (1/k

RÅ!$# EG/'& o0Z 1 / * #$:'10' # *8/ #n#$+9 24* !$#n:'#Hs

9|1 /'*1 + |Rs| L ( 1 /'( #LÎÅ1 & ,s!$#$2 o 2 #4HI#4 ( M310 ( HM & ( #4? (n& : 2 9|#4 : ( R 6 #Iξ &)(8EG/ # 6 #

k@Ê© HI# 246F2 HI#4 ( :'# 6 /'&)( #31 &)(f/

* #$!$1 * :Ì: 2 9^#4 : / &FEN/ #4HI#4 ( :'# 6 w!$10Hn9? * & 310 /.y246F2 HI#4 ( 79 *32 ! 2 :'#4 ( B, & : 2 9^#4 :'#4HnHI#4 ( :'#6 # /'* 1 * : * #:sr & 5# *+(+& 10 S Q=N\ * !$10 2$EG/ #4 ( ,?10; ­ ± ÇDM¬L«3­ |Rs|

² $ ª ± x )4ÄÅ«+­LÃ;²-«Ç0¯ÅÄ Ãw²G­s#­UÃ4IJ0¯ÃLÄÅ«L¯Ð¬LÆ ;x5ÇD I­;z)ªÃ4ÇD M­²N­

s− 1aª0«L¯ÅªG¬Lz)­LÃf²N­­4« ± Ç-ÆGz z ¯ ¯ ± ²GÊÈ'­ ± ²Nª ± ÄÊ­Uà #´²N­"Èa«ÇG¬+ªN¬L¯ z ¯ÅÄÊUà 1/i

È.Ç-ÆG«iaª0«L¯Ðª ± ħ²G­ 2

Bs!

f­ )M­ #JzF­ ± ÇDM¬L«+­ |Ls|² $ ª ± xQ)4ÄÅ«3­Uò-«Ç0¯ÅIJN­

s#­UÃLÄ%²0¯ÃLÄÅ«L¯Ð¬LÆ wx3ÇD M­Zz)ª;Ã$ÇD M­Z²G­

n − saª0«L¯ÐªN¬LzF­UÃf²N­­4« ± Ç-ÆGz z ¯ ¯ ± ²GÊÈ'­ ± ²Nª ± ÄÊ­Uà #´²N­<Èa«+ÇN¬+ªN¬L¯ zɯ ÄÊUà 1/iÈ.Ç-ÆG«

iaª-«U¯Ðª ± Ä´²N­ 2

Bn− s + 1

!y & ( #4? (JEN/ # 1 / ": & +9^1-310 ":'# 6 6 1 & ,9|# /'(@ (+* # / & Hn9 6 #=!B 6 ! /'6 :'#=o- *+& !$#% / K * @¾(@¾&)6

~ !$10 ! 6)/'* #fl rt# # * ! & !$# /'& o- ( 9^# * HI# ( :'#HI10 (+* # *EG/ r &)6 mrt#4#$ (<*+& #4mQ ± «3­ÊÈa«3­ ± ²Zz)­Là ± Ç-ľª-ÄůÐÇ ± à È|«++xU+²N­ ± ÄÊ­LÃ

Rs­UÃ4ÄzF­ ± ÇLI¬4«+­8² $ ª ± xQ)4ÄÅ«3­UÃ8²0«+Ç0¯ÅÄ Ã²G­z)ªx4zF

s²Nª ± ÃÆ ± ª0«B¬L«3­q¬L¯ ± ª0¯«3­f²N­7«+­3xL³.­L«+xL³.­Mª0z)3ª-ľÇ0¯ «+­q²N­8ľª0¯ z z)­

n# ²pÇ ± Ä z)­LÃ8x4z)LÃÃ4Ç ± Ä 1, . . . , n

! ! UÈa«L¯2M­L«z)ªwo- *+& !$#²G­ |Rs|

Ã4Ç0ÆGÃz)ª*$Ç0«I­f² $ Æ ± ­%Ã$ÇD M­7²NDÈ'­ ± ²pª ± Ä<²N­ s!

Page 60: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

ÒÑ ! #""$#% & #'('(*)+, ! 'yÇ ± ÄÅ«3­L« & Æ'­z($ Ç ± ª

Var(|Rs|) = Hs−O(1) z)­

O(1)­LÃLÄ\¯Ðx4¯vÆ ± ¯ 4Ç-« M­ m¯z^²pÇ0¯ÅÄ ­0¯ÃLÄÊ­L«=Æ ± ­Iª B$Ç0«+ª-ÄůÐÇ ± ¯ ± ²NDÈ'­ ± ²pª ± ÄÊ­fª0ÆNÃUÃU¯´¬4¯Ð­ ± ²N­

s & Æ ­q²N­ nL!

! ´ÈpÈazɯ & Æ'­L«7z($ ¯ ± Fpª0zɯ ÄÊ8²N­\xL³.­B¬ I-x4³.­ BIz)ªCaª0«U¯ÐªN¬LzF­fª0zF+ª-ľÇ0¯ «+­ |Rs|#|È.Ç-ÆG«7ÇN¬$ÄÊ­ ± ¯ «Æ ± ­&aª0zF­LÆ«

kÄÊ­Lz z)­ & Æ ­ P(|Rs| > k) < 1

n

! ± È.Ç0Æ«U«+ªZÃUÆÈpÈ.Ç0Ã$­L«n/4 ≤ s ≤ 3n/4

!

N /'& EN/ # / & Hn9 6 #Z!B 6 ! /'6 :'#Zo0 *+& !$#Z #M 1 / f9^# * HI# ( 9?0f:'#!$10 ! 6)/'* #-, &)6 !$10No & #4 ( :'#3#* >? (+(+* #% /'* / # & 2 PN 6)&)(32 9|1 *+( ( ,G:'#HM &F©4* #=P 2 24* 6 #-,G /'*§6 #$´310HnHI#$´:'#Jo- *+& > 6 #$< 6F2 ( 1 &)* #$& : 2 9^#4 : ( #$f 6 rA¯ ± Fpª0zɯ ÄÊq²N­ v³.­4« ± Ç R op1 &)*J6 r¶' # # , & 2 PN 6)&)(32 Q S QM 6 #$ ( ! 6 &)* ,-:sr¶9 *3© 6 : & 5! / 3 & 10n9 *32 ! 2 :'#4 ( #-, EN/ #-,9^1 /'* :'#$!$10 ( ( #$

C1# (

C29'9 * 109 *+&F2 #$,

# (n033#P * :s, 10

ln(n)− C1 ≤ E(As) ≤ 2 ln(n) + C2.

Ï!$10 2$EN/ #4 !$#-,?10Ï.,':sr¶9 *3© 6 r & 2 PN 6)&)(32 :'# ¦ O # * 1 µ ,

P (As > (1 + δ)(2 ln(n) + C2)) ≤(

(1 + δ)1+δ

)ln(n)−C1

&m6 rt109 * #4 :δ053#P * :9^1 /'*dEN/ # 6 rt10Ï &)(

(1 + δ)1+δ<

1

2

R 9? * # #4Hn9 6 #δ = 1.4 S ,a10;10> (+& #4 (

P (As > (1 + δ)(2 ln(n) + C2)) <C ′

n2.

N\ * !$10 2$EG/ #4 ( , 6 9 * 10>?> &)6)&)(32IEG/ # 6 r / #M / HI1 & :'#$no0 *+& > 6 #$7 6F2 ( 1 &)* #$

As31 &)( 9 6)/

P * : EG/ #(1 + δ)(2 ln(n) + C2)

RÅ!-rt#$ (@D~ : &)* # EG/ # 6 8O? /'( # /'*h31 &)( 9 6)/ <P * : EG/ #%!$# (+( #%HI4HI#

o- 6 # /'* S ,a#$ ( HMu+1 *32 #79? *C ′/n

QHI * ,h#$ ( ,?:'#8HM &F©4* #q!$# *+( & #-,aHMu+1 *32 #89? *

nQIyM:'10 !-,^#4

9^1-5 (f(n) = (1 + δ)(2 ln(n) + C2)

,

E(h) ≤ f(n)P(h ≤ f(n)) + nP(h > f(n))

≤ f(n) + C ′

I®Z:'10 !8> & #4E(h) = O(log n)

,|!$# EN/'& 9 * 1 / op# 6 # ( O 2 1 *3© HI#n# ( 9^# * HI# ( :sr¶K * HI# *EG/ #-,^#4HI1 C #4' #-,a!3O? EG/ #H & 3# ~ u+1 /'* 1 /* # EG/ ( # /'*</ (+* #B9 /'* / ;!$1 (

O(log n)Q

R%SR w]<ÁqÂ3ke»fkf]dºf]dgdk #ľªG¬Lz)­²N­³ªpx4³ª"FN­ RD³ªÃU³GľªN¬LzF­Ì#4 'P 6 & S #$ (Z/ #y (+*+/ ! (+/'* #y:'#:'10' 2 #$w9|# * HI# (+( (

:srt# µ #$! (+/ # * 6 #$ 109 24* (+& 10 7?^v? , 3 s # ( 7's s #4 ( #4Hn9 #$53#4 (+& # 6)6 #4HI#4 ( !$10 ( ( L#4®!$10 (+* #49? *+(+& #-, 6 rt#$+9?0!$# * # EG/'& #$ ( 9 6)/ & Hn9^1 *+( ( ,v# (&)6 #$ ( !$1 ( # /. :'#q9? * !$1 /'*+&)*6 rt#4 3#4H8> 6 #:'#$d10>.u+# ( d!$10 ( #4 / %: 6 ( > 6 #-Q

l rt#4 5#4H7> 6 #:'#$<! 6F2 <3# * 8 1 (32K,Bop#$!

m = |K| Q=Iw9^1 /'*+* 89? * # #4Hn9 6 # / 9'9^1-3# *"EN/ # 6 rt10

K = 0, 1, . . . ,m− 1 Q

Page 61: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

g'()+ ( Ò-Ò2/.420. @@?>98;g@A

# & : 2 # 246F2 HI#4 ( &)* #9|1 /'* # µ #$! (+/ # *<* #$!3O # * !3O #$J# ( H & 5#$ ~ u+1 /'* #4 ( #4Hn9 <!$10 ( ( ,'!$10 & ( #~ ( 1G! p# *8/ # ( > 6 # & :'# '2 #M9? *f6 #$q! 6F2 RÅ#4¹:sr¶ /'(+* #$ ( # * HI#$B, / ( > 6 #B / :'# ( &)6)6 #

m S L 9^1 /'*!3O? EG/ #q! 6F2x, 6 Z!$# 6)6)/'6 #q:sr & : & !$#

x!$10 (+& #4 : * 31 &)( RÅBr &)6 mr C I9?0%:sr 246F2 HI#4 ( :'#8! 6F2

k:

6 rt#4 3#4H8> 6 #S S ,'31 &)( u

&u#$ (<6 r 246F2 HI#4 ( RÅ / 9'9^1- 2%/ &FEG/ # S :'#! 6F2 x

: SQ

l r & !$10Go 2 & #4 ( HMu+# /'* :'#;!$# (+( #9'9 * 1!3O #Ï#$ (M2 o & :'#4 ( &)6 5# &)(+/ # / & op#B / :'# 6 rt#$+9?0!$#H 2 HI1 &)* # * # EG/'& BQ"% 6 #$w!B0 (ÊC 9 &FEG/ #$B,

mR 6 ( &)6)6 #y:'# 6 rt#$39?0!$#:'#$! 6F2 S #$ ( :'#>^#B / !$1 / 9

/ 9 24*+& # /'*~f6 ( &)6)6 #:'#$#4 3#4H7> 6 #$ EN/ # 6 rt10: 2 &)* # * #49 *32 3#4 ( # * ,a# ( ,'#4 ( 1 /'(J24( ( :'#!B / 5#-, &)6 #$ (& Hn9 * (+& !B> 6 #I:'#n ( 1! p# */ ( > 6 #B / :'# ( &)6)6 #

mR 9^#4 3# *7~

m = 232 ,^!$# EN/'& !$1 *+* #$+9^10 :® / !B01 6 #$d! 6F2 J310 ( :'#$J#4 (+& # * J /'*</ #HM0!3O & # Lq> &)( S Q2/.420.21 @@?>98;=7%; 9 4 9 6 4 7 6; @ @+;

#nľªN¬LzF­q²N­³ªpxL³.ª"FN­f#$ ( !$10 (+&)(+/ 2 #7:'#$ 246F2 HI#4 ( = /'& o- ( / ;#4 5#4H7> 6 #

K:'#! 6F2 B, :'# ( &)6)6 #

m L / ;#4 (+& # *n < m L N : 2 & P- # * 6 rt#4 3#4H8> 6 # 0, 1, . . . , n− 1 L / ( > 6 #B /

T,':'# ( &)6)6 #

n, & :'# '2 9? *d6 #$ 246F2 HI#4 ( J:'#

N L / #*4Ç ± x$ÄůÅÇ ± ²N­³ªpx4³ª"FN­h, EN/'&~ !5O? EN/ #! 6F2

k ∈ K0531G! & # / 246F2 HI#4 ( :'#

NQ

l r & : 2 #J:'#<>?03#<#$ ( ÎÐ1 *+( & Hn9 6 # 6 rt10>.u+# ( :'#<! 6F2x,-r &)6 # & ( #-,-#$ ( ( 1G! 2 : 6 %!$# 6)6)/'6 #

T [h(x)]Q

@<Ç0Æ«8Æ ± ­ $Ç ± x$ÄůÐÇ ± ²N­q³ªpxL³.ª"FN­h#<Ç ± ²-¯«+ª & Æ,$ ¯ zvÃ$­JÈa«+ÇB²0ƯÅÄ"Æ ± ­M!$1 6)6)& & 10 ­ ± ÄÅ«+­²N­LÆ x4zFUÃ

x­4Ä

yÃL¯

h(x) = h(y) Ç ± ²0¯ «ª & Æ,$ Æ ± ­8ÄÊ­Lz zF­8x5Ç0zzɯÃU¯ÐÇ ± ªZzɯЭ4Æ­ ± h(x)

! @ ± ­ $Ç ± xBÄůÅÇ ± ²N­=³ªNxL³ª"FN­f­UÃ4Ä ²0¯ ÄÊ­9? * ξ &)( #=È.Ç0Æ«%Æ ± ­ ± Ã$­ I¬4z)­ S ⊂ K

ÃL¯­4zzF­ ± ­Èa«+ÇEaÇ & Æ'­nª-Æ.x4Æ ± ­qx3Ç-zzɯ ÃL¯ÅÇ ± ­ ± ÄÅ«+­8zF­UÃ8LzFM­ ± Ä Ã8²N­ S!

M 6 #$ ( ! 6 &)*<EG/ #-,N9^1 /'*"( 1 /'( #4 5#4H7> 6 #S:'# ( &)6)6 # / 9 6)/

n, &)6 # & ( # / #ÎÐ10 ! (+& 10w:'#O?0!3O?Pp#

9? * ξ &)( #R 9?0vÎÐ1 * ! 2 HI#4 ( ξ0! &)6 # ~ !B 6 ! /'6 # * S 9|1 /'* SQ * #4o0 !5O #-, &)6 #§9|# /'( 9?0\# .& ( # * :'# ÎÐ10 ! (+& 10

:'#dO?0!5O?Pp# EG/'& 31 &)( 9? * ÎÐ &)( #J9|1 /'* xL³ª & Æ ­%31 / @ #4 3#4H7> 6 #=:'# ( &)6)6 # k ≤ n:sr / Z#4 3#4H8> 6 #J:'# ( &)6)6 #

/ 9 24*+& # /'* # ~nR ( 1 /'( & Hn9 6 #4HI#4 ( 9? * !$# EG/ r &)6´C /'* ÏÎÅ1 * ! 2 HI#4 ( / HI1 & I:'# /. 246F2 HI#4 ( EG/'&

/'* 10 (<6 8HI4HI# & HMPp#-,'# ( :'10 !-, 6 7ÎÅ10 ! (+& 10:'#=O?0!3O?Pp# #=5# * 79?0"9? * ξ &)( #=9|1 /'*"/ #4 3#4H8> 6 #!$10 ( #4? ( :'# /.w( # 6 246F2 HI#4 ( S Ql831 6)/'(+& 10w0:'109 (32 ##$ ( ! 6 03 &FEG/ #7G!3O 1 & &)*´/ #<ÎÐ10 ! (+& 10:'#JO?0!3O?Pp# 6F2 ( 1 &)* #4HI#4 ( 9? * H &|/ !$# *+( & Ì#4 3#4H7> 6 #n:'#7ÎÐ10 ! (+& 10 B,^:'# ( # 6)6 #f31 *+( # EG/ rt# 6)6 #f51 &)( ,a:'#8HM &F©4* # (+*3© =9 * 10>?> 6 #-, Ë 9 * #$ EN/ #LÍ9? * ξ &)( # !-rt#$ (@D~@ : &)* # EG/ rt# 6)6 #9 * 1op1 EG/ #9^# / :'#!$1 6)6)& & 10 BQ2/.420.43 @6 9A9e; 7

2 A 6j; =7l;:9 9e;=7 6 ; 4 9 6 4 7 6; @ @+;

@ ± ­ ± ÃB­M¬LzF­H

²N­ 4Ç ± x$ÄůÅÇ ± òN­;³ªpxL³ª FN­®­UÃ4Ä7Æ ± ­ÏξH &)6)6 #2@¾/ & op# * 3# 6)6 # ÃL¯ #

& Æ ­Lz à & Æ ­Ã$Ç0¯Ð­ ± Äz)­UÃLzFM­ ± Ä Ã x­$Ä

y²N­

K#Ç ± ªD#ÃU¯

h­UÃ4ÄÆ ± ­/4Ç ± x$ÄůÅÇ ± Èa«U¯Ã$­%ª-z)+ªpľÇ0¯«3­M­ ± ħ²pª ± Ã

H ÃB­LzAÇ ± z)ª²0¯ Ã4ÄÅ«U¯¾¬LÆ.ÄůÅÇ ± Æ ± ¯ 4Ç0«M­ #

P(h(x) = h(y)) ≤ 1

n.

RÅ 6 r & 2 PN 6)&)(32 ! &A@ :'#$3 / , 6 89 * 10>?> &)6)&)(32 9^1 *+( # /'*"6 #=!3O 1 &A :'# 6 ÎÐ10 ! (+& 10h:

H L !$# (+( #& 2 PN 6)&)(32 :'1 &)( (+* #o 24*+&A?2 #7 & H /'6)( 2 HI#4 ( 9|1 /'* ľÇ0ÆGà 6 #$d!$1 / 9 6 #$:sr 246F2 HI#4 ( =:'#KQ Slo0 6 # /'* :'#

1/n!$10HnHI# 6)& H &)( #:'#<9 * 10>?> &)6)&)(32 :'#J!$1 6)6)& & 10m,N!$1 *+* #$+9^10 : ~ !$# EN/ # 6 rt10M10> (+& #4 (

!$10HnHI#9 * 10>?> &)6)&)(32 :'#!$1 6)6)& & 10w & 6 #$ & HMPp#$§:'# ( 1 /'( #$ 6 #$´! 6F2 510 ( !3O 1 & & #$ / & ÎÐ1 * H 2 HI#4 ( :

Page 62: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

Ò< ! #""$#% & #'('(*)+,

N, & : 2 9^#4 :'#4HnHI#4 (6 #$ / #$%:'#$ /'(+* #$ L :'#q!$#f9|1 & ( :'#8o / #-, 6 #$=ÎÅ10 ! (+& 10 :'#fO?0!5O?Pp#n:sr / #ξH &)6)6 #

2@¾/ & op# * 3# 6)6 #73#!$10Hn9^1 *+( #4 (/ ;9^# / !$10HnHI#:'#$"ÎÐ10 ! (+& 10 6F2 ( 1 &)* #$BQ

N\ * &)6)6 # /'* B,a!$# (+( #8o- 6 # /'* :'#1/n

#$ ( : & KM! &)6 # ~ >? (+(+* #-,a# ( #$ ( 0 C Hn9 ( 1 (+&FEG/ #4HI#4 ( 109 (+& HM 6 # L10;9^# /'( HI10 (+* # *=EN/ #-,.9^1 /'*d( 1 /'( #ÎÐH &)6)6 #H, &)6 # .& ( #:'# /. ! 6F2

x# (

y( # 6)6 #$ EG/ # 6 q9 * 10>?> &)6)&)(32

:'#!$1 6)6)& & 10Ï#4 (+* #x# (

y31 &)( / HI1 & d:'#

1/n− 1/mQ

.& ( # @¾(@¾&)6 :'#$IÎÐH &)6)6 #$2@¾/ & op# * 5# 6)6 #$Z:'#wÎÐ10 ! (+& 10 M:'#;O?0!3O?Pp#l *32 9^10 3#;#$ ( 1 /'& L 9? *# #4Hn9 6 #-, 6 rt#4 3#4H8> 6 #:'#ľÇ-ÆÄÊ­Uà 6 #$ÎÐ10 ! (+& 10 :'#

K:

N!$10 (+&)(+/ # / # ( # 6)6 #<ξH &)6)6 #-Q v1 /'( #LÎÅ1 & ,

9^1 /'*<& Hn9 6F2 HI#4 ( # * :'#$ ( > 6 #$J:'#%O?0!3O?Pp#$d#LKM!B0!$#$B, 1 / J$op10 <>^#$31 & :'#=ξH &)6)6 #$ EN/'& o 24*+&A #4 (:'#$!$10 : &)(+& 10 / 9'9 6F2 HI#4 ( &)* #$ 6 #$ÎÐH &)6)6 #$ :'1 & op#4 ( (+* #":'#"9|# (+&)( # ( &)6)6 #&R 6 ( > 6 #<:'#4o * = ( 1G! p# * / KM5HnHI#4 ( :sr & .ÎÐ1 * HM (+& 10 9^1 /'* : 2 ! *+&)* #I!$10Hn9 6F©4( #4HI#4 (f/ 246F2 HI#4 ( :'# 6 ZξH &)6)6 # S ,m# (&)6 :'1 &)( (+* #f9|1-5 & > 6 #-, ~ 9? *+(+&)* :'# 6 Z:'#$3! *+& 9 (+& 10 Ë !$10Hn9?0! ( #LÍq:sr / 246F2 HI#4 ( :'# 6 IξH &)6)6 #-,|:'#f!B 6 ! /'6 # *6 o- 6 # /'* :'# 6 fÎÐ10 ! (+& 10:'#%O?0!3O?Pp#79|1 /'*d/ #! 6F27EN/ # 6 !$10 EG/ #-Q

&=6 rt10 : & +9^1-3#Ï:sr / #;ξH &)6)6 #2@¾/ & op# * 3# 6)6 #Ì0!$!$#49 ( > 6 #

H, 6 r & Hn9 6F2 HI#4 ( (+& 10 :'# ( > 6 #$w:'#

O?0!3O?Pp#q:'#4o & #4 ( ! 6 &)* #Z ~n6 M! *32 (+& 10:'# 6 ( > 6 #-, / 246F2 HI#4 (h ∈ H

#$ ( !5O 1 & & 6F2 ( 1 &)* #4HI#4 ( ,# ( 5;:'#$3! *+& 9 (+& 10 #$ ( ( 1! 2 ##4¹' # #Z:'# 6 ( > 6 #-Q ¦ rt#$ ( !$# (+( #MÎÅ10 ! (+& 10 :'#IO?0!5O?Pp# EN/'& #$ (#4 /'&)( # /'(+&)6)&F2 #9|1 /'*d(+* &)( # *J( 1 /'( #$ 6 #$ * # EG/ ( #$d# ( H & 3#$ ~ u1 /'* :'# 6 ( > 6 #-Q

M 6 #$ ( 2 !$#$3U &)* #:'#Z9 *32 op1 &)*n/ HI1 C #4 :'# (+* &)( # *f6 #$q!$1 6)6)& & 10 ,vHI4HI#w &´6 # C (3© HI# 24(32!$10 H / 9^1 /'*JEG/ rt# 6)6 #$51 & #4 ( 9^# / 9 * 10>?> 6 #$BQalI51 6)/'(+& 10 6 q9 6)/ & Hn9 6 #7!$10 & ( # ~ ( 1! p# *J( 1 /'( #$6 #$ ! 6F2 " C ("/ #dHI4HI#do- 6 # /'* :'#JO?0!3O?Pp#%31 / 6 %ÎÐ1 * HI#J:sr / # 6)& ( #J!3O?:FF 2 # L !5O? EN/ # * #$!3O # * !3O # /'* I 6 1 * !$10HnHI#7!$1 ( , #4;9 6)/ :sr / # 2 o- 6)/ (+& 10Ï:'# 6 8ÎÐ10 ! (+& 10Ï:'#O?0!5O?Pp#-, 6 6 10'P / # /'* :'# 6 6)& ( # ( 1! 2 #7: 6 q!$# 6)6)/'6 #!$1 *+* #$+9^10 : ( #f:'# 6 ( > 6 #-Q

&\6 rt10yξ &)(=6 r O C 9^1 ( O © 3# EG/ # 6 r 2 o0 6)/ (+& 10:'# 6 MÎÐ10 ! (+& 10®:'#8O?0!5O?Pp#I3#8ξ &)( #4 ( #4Hn9 O(1)

,10wHI10 (+* #=ξ0! &)6 #4HI#4 (dEG/ #-,N9^1 /'* ľÇ0Æ.ÄÊ­ 2$EG/ #4 !$#%:'#

r109 24* (+& 10 ~ 9? *+(+&)* :sr / # ( > 6 #%o & :'#-, ( # 6)6 #

EG/ r ~ / ! / ;HI10HI#4 (d6 ( > 6 # #!$10 (+& #4' #9 6)/ d:'#s246F2 HI#4 ( zR 9? * # #4Hn9 6 #-, &

s#$ ("6 #% 10H7> * #

( 1 ( 6 :sr & 3# *+(+& 10 89? * H & 6 #$8109 24* (+& 10 S , 6 rt#$+9 24* !$#Z: / !$1 (( 1 ( 6 #$ ( HMu1 *32 #I9? *r(1 + s

n)QN1 /'* 9^# /¹EN/ #

n31 &)( 9 6)/ 8P * : EG/ #

s,v!$# (+( ##$+9 24* !$#Z#$ (8& .Î 24*+& # /'* # ~

2rQv%#Z9 6)/ B,v!5O? EN/ #

109 24* (+& 10m, & : & o & : / # 6)6 #4HI#4 ( ,s / ;!$1 ( :'10 (6 rt#$+9 24* !$#7#$ (O(1 + s/n)

Q2/.420. G4 7:9L=A 9 6A4 O6 A ;L;; 9 6 9<; @ ?6 9A98;

2 A 6 j; =7:; 9A9e;

G=1 / 6)6 10 HM & ( #4? ( 9 *32 5#4 ( # * / I# #4Hn9 6 #<:'#´Î¾H &)6)6 #<:'#"ÎÅ10 ! (+& 10 :'#"O?0!3O?Pp# EG/'& o 24*+&A #6 #$!$10 : &)(+& 10 2 10 ! 2 #$9 *32 ! 2 :'#4HnHI#4 ( / #4 3#4H8> 6 #I:'#qÎÐ10 ! (+& 10 :'# * & 310'?> 6 #4HI#4 ( ξ & > 6 #!B * : & ? 6)&)(32 ,'ξ0! &)6 # ~ : 2 ! *+&)* ## (=~q2 o0 6)/ # * , # (EN/'& 9^1-3 © :'# 6 f9 * 109 *+&F24(32 :'#

2@¾/ & op# * 5 6)&)(32 Q

1 &)(p/ ; 10H7> * #89 * #4H & # * / HI1 & 2 PN 6\~

mR &)6 #4# & ( #7 / HI1 & / #4 (+* #

m# (

2m,?# (

mr & Hn9^1 *+( # 6 # EN/ # 6 ÎÅ# * 6 r¶ µ &)* # S Q=G=1 / J 6)6 10 (+* Bo0 &)6)6 # * : 6 #!$1 * 9 Zp:'#$J#4 (+& # * dHI1: /'6 1

pQ

G=1 / < 1 ( 10 g6 8ÎÅ10 ! (+& 10:'#

Zp:

N: 2L & #9? *

g(x) = x mod nQ

N1 /'*a, b ∈ Zp

,'31 & #4 (fa,b

6 8ÎÅ10 ! (+& 10 RÐKI # S :'# Zp: 6)/'&A@ HI4HI#-,?# (

ha,b6 8ÎÐ10 ! (+& 10:'#

O?0!3O?Pp#-,a: 2L & #$d9? *

fa,b(x) = ax + b( mod p),

ha,b(x) = g(fa,b(x)).

@ : mª $ªDq¯z zF­H = ha,b : a ∈ Z

∗p, b ∈ Zp

#8­UÃLÄ%Æ ± ­ $ªDq¯ zzF­ 2°ÊÆ ± ¯ a­L«UÃ$­Lz zF­²N­

$Ç ± x$ÄůÐÇ ± Ã7²N­³ªpxL³.ª"FN­"! 1 & #4 (

x# (

y:'# /. ! 6F2 : & (+& ! ( #$B,m# ( 31 &)(

h = ha,b ∈ HQG1 ( 10

r = fa,b(x)# (

s = fa,b(y)Q 1 /'( :sr¶>^1 * :s, * #4HM *3EG/ 10 EN/ #-,a: © 6 1 * EN/ #

a 6= 0,fa,b

#$ (J/ #¬L¯ BB­+x$ÄůÐÇ ± /'*Zp L

Page 63: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

g'()+ ( Ò9? * !$10 2$EG/ #4 ( ,

r 6= s,^# (&)6 #89^# /'( 3#f9 * 1: /'&)* # / #f!$1 6)6)& & 10#4 (+* #

x# (

yEG/ #n &

r# (

s510 (

:'# /.246F2 HI#4 ( =: & (+& ! ( J:'#Zp

( # 6 EN/ #g(r) = g(s)

Q #4Nop# * 310 6 #$ *`_06 #$I ' 10 r

# (s!$10HnHI# 24( ( :'# /.®246F2 HI#4 ( 8: & (+& ! ( EG/ # 6 !$10 EN/ #$8:'#

ZpQHM 6 # & ( # / / &FEG/ #f!$1 / 9 6 #

(a, b)( # 6EN/ #

fa,b(x) = r# (

fa,b(y) = sR &)6 Br¶P &)( :sr / y C (3© HI#

6)& 2 &)* #:'# 2$EG/ (+& 10 ~ & !$10' / #$B,a: Zp

ax + b = r

ay + b = s

lm#8: 24( # * H & ? ( :'#!$# C (3© HI##$ (x− y

, EN/'& #$ (d& Nop# * & > 6 #7: Zp

, !$# EG/'&m& Hn9 6)&FEG/ ## .& ( #4 !$## (</ & ! &)(32 :'# 6 I31 6)/'(+& 10mQ SG=1 / n5$op10 n:'10 ! EG/ #-,9|1 /'*

x 6= yEG/ # 6 !$10 EN/ #$, 6 #M 10H8> * #;:'#ZÎÅ10 ! (+& 10 n:'#O?0!3O?Pp#:'#

HEN/'& 9 * 1op1 EG/ #4 (8/ #M!$1 6)6)& & 10 #$ ( # 0! ( #4HI#4 (86 #I 10H7> * #Z:'#I!$1 / 9 6 #$

(r, s),$op#$!

r 6= s, ( # 6

EG/ #g(r) = g(s)

Q #4HM *3EN/ 10 EG/ #q!$#q 10H7> * #q #n: 2 9^#4 :y9?0:'#x & :'#

y 6 9 * 10>?> &)6)&)(32 :'#

!$1 6)6)& & 10#4 (+* #J:'# /. ! 6F2 #$ ( 6 %HI4HI#<9^1 /'* ( 1 /'( #$ 6 #$ 9? &)* #$ :'#d! 6F2 Q G1 / 1 ( # * 10 α!$#< 10H7> * #

:'#!$1 / 9 6 #$BQN1 /'*

z ∈ N,s31 &)(

Az = r ∈ Z : g(r) = z Q+N\ * !$10 (+*+/ ! (+& 10:'#g,s10 bp/nc ≤ |Az| ≤

dp/ne Q=I * , 6 #% 10H7> * #:'#=ÎÐ10 ! (+& 10 d:'#%O?0!3O?Pp#8:'# HEG/'& 9 * 1Bop1 EN/ #4 ( #4

z/ #!$1 6)6)& & 10;#4 (+* #

x# (y#$ ( , :sr¶9 *3© 6 #!B 6 ! /'6 9 *32 ! 2 :'#4 ( , |Az|(|Az | − 1)

QN1-310

a = bp/nc L 31 &)( #4 k6 #7 10H8> * #q:'#

z ∈ N9^1 /'*6 #$ EN/ # 6 %10Ì |Az| = a

,|# ( :'10 !n − k

6 #; 10H7> * #;:'#z9|1 /'*n6 #$ EG/ # 6 |Az | = a + 1 = dp/ne Qlm#$M: &Aµs24* #4 (

AzÎÅ1 * HI#4 (I/ #

9? *+(+&)(+& 10Ï:'#Zp

,'# ( 9? * !$10 2$EG/ #4 ( 10Ï

p = k.a + (n− k)(a + 1).

G=1 / J$op10 :'10 !

α = ka(a− 1) + (n− k)(a + 1)a

≤ (ka + (n− k)(a + 1)) a

≤ p⌈ p

n− 1⌉

≤ p

(

p + n− 1

n− 1

)

≤ p(p− 1)

n

I * , 6 #7 10H8> * # ( 1 ( 6 :'#7ÎÅ10 ! (+& 10 %:'#7O?0!3O?Pp#n: H

#$ ( # 0! ( #4HI#4 (p(p − 1) L 9? * !$10 2L@EG/ #4 ( , 6 79 * 10>?> &)6)&)(32 9|1 /'*

x# (

y:srt#4 (+* # * #4!$1 6)6)& & 10 R EG/'& #$ ( :'#

α/|H| S #$ ( > & #4 & .Î 24*+& # /'* #1 /2 PN 6 # ~

1/nQ

2

¦ # (+( #MÎÐH &)6)6 #H

*32 9|10 :> & #4 ~ 1 (+* #I9 * 10> 6F© HI#ym9^1 /'* 9^# /EG/ # 6 rt10¹!3O 1 & & 33#p = O(m)

,6 #!3O 1 &A :'#

a# (

b!$1 ( # * Ï / 9 6)/

2 log p = O(log m)> &)( f 6F2 ( 1 &)* #$B,\# (f6 #M ( 1! -Pp#:'#

a# (

b #I 2 !$#$3 &)( # * 9?089 6)/ 7:'#IH 2 HI1 &)* #-Ql r 2 o- 6)/ (+& 10 :'# 6 wÎÐ10 ! (+& 10:'#MO?0!3O?Pp#-,# 6)6 #Z / 3 & , #

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Page 64: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 65: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 66: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

! #""$#% & #'('(*)+,

Page 67: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

¦ #§!3O?9 &)(+* #§ # 3#9 *324( #4 :79?0 / f!$1 /'* v!$10Hn9 6 # ( :'# 9 * 10>?> &)6)&)(32 L &)6 3# !$10 ( #4 ( #":'# *32 / HI# */ !$# *+( & 7 10H8> * # :'# : 2L &)(+& 10 # ( :'# *32 /'6)( ( , 246F2 HI#4 ( &)* #$1 / 10m,B:'# 6 ( O 2 1 *+& # :'#$s9 * 10>?> &)6)&)(32 Q

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Page 68: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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NM D : ^Ç0¯ ÄΩ

Æ ± ­ ± ÃB­M¬Lz)­ ± Ç ± aB¯Ð²N­ #­4ÄE

Æ ± ­ ± Ã$­M¬LzF­ & Æ'­LzÉ°x3Ç ± & Æ'­²N­ È.ª0«4ÄůЭLÃ=²N­ Ω! mª (+*+& > / #4'Pp#4 : *32 #J9? *

E# ± ÇpÄÊ3­ σ(E)

#­UÃ4ÄzAªdÈazÉÆNà È'­4ÄůÅÄÊ­=ÄÅ«U¯¾¬LÆ ª0ÆnÃB­ ± òN­=z%$ ¯ ± x$z ÆGÃU¯ÐÇ ± & ÆG¯x3Ç ± Äů¾­ ± ± ­ E x:$ ­LÃLÄ ­ ± x5Ç0«+­z%$ ¯ ± ÄÊ­L«UÃ$­+xBÄůÅÇ ± ²N­%ľÇ0Æ.ÄÊ­UÃzF­UÃ%ÄÅ«U¯¾¬LÆGà & Ư x3Ç ± Äů¾­ ± ± ­ ± Ä

E!l rt# .& ( #4 !$#:'#

σ(E)#$ ( 05 /'*32 #=9? *<6 * #4HM *3EN/ #%9 *32 ! 2 :'#4 ( #-,?# ( 9? *<6 8PN * (+& # EG/ r &)6 # & ( #

( 1 / u+1 /'* d / HI1 & / # (+*+& > / !$10 ( #4? (E, ~ 5$op1 &)* , 6 (+*+& > / ÎÐ1 * H 2 #%:'# ( 1 /'( #$ 6 #$"9? *+(+& #$d:'#

ΩQ

D : mª (+*+& > / >^1 *3246)& #4' #fÃUÆ«R

­UÃ4Ävz)ªqÄÅ«L¯Ð¬LÆ­ ± FN­ ± ²0«33­=ÃLÆG«RÈ.ª0«7z($ ­ ± ÃB­M¬Lz)­f²N­Lï ± ÄÊ­4« aª-zzF­UÃ8²N­

R!

l (+*+& > / >^1 *3246)& #4' #M!$10 (+& #4 ( ,\#4 (+* # /'(+* #$B, ( 1 / 6 #$ & ( # * o- 6)6 #$%RÅ1 / op# *+( B,sÎÐ# * H 2 B,m1 / 3#4H &A@1 / op# *+( S ,? & &EN/ # 6 # /'* / & 10 J: 2 10H7> * > 6 #$Ql (+*+& > / >|1 *3246)& #4' #%3# *+( :'# Ë (+*+& > / 9? * : 2 ξ /'( Í5,.#4Z!$#=3#4 EN/ #-,!3O? EG/ #dÎÐ1 & EN/ # 6 rt10Z9? *+6 #%:'#o- *+& > 6 #7 6F2 ( 1 &)* # *32 # 6)6 #-, 6 rt#$39?0!$#HI#$ /'* > 6 #31 / @ u+0!$#4 ( #$ (

RH / & :'# 6 (+*+& > / >^1 *3246)& #4' #-Q

|Ç0¯ÅÄ(Ω,F)

Æ ± ­UþÈ.ªNx5­ M­UÃLÆG«+ªN¬LzF­"! ± ­ $Ç ± x$ÄůÐÇ ± µ#d²NE ± ¯Ð­qÃUÆ« F­4ÄB%aª0zF­LÆG«UÃn«+5­LzzF­UÃ=È.ÇÃL¯ Äů a­UÃIÇ0Æy¯ ± E ± ¯¾­UÃQ#<­UÃLÄ<Æ ± ­MHI#$ /'* #f9^1- &)(+& op#wÃU¯<­Lz z)­CaL«L¯ E´­IzF­UÃqx3Ç ± ²0¯ÅÄůÅÇ ± ÃÃUƯ aª ± ÄÊ­UÃ

Page 69: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

$*" #"c " ig #"i

µ(∅) = 0 ÃU¯

(Ai)i∈I­UÃ4Ä<Æ ± ­ $ªDq¯z zF­ E ± ¯¾­nÇ0Æ®²N ± ÇDM¬L«ªG¬Lz)­Z²N­=È.ª0«4ÄůЭUà M­UÃUÆ«+ªN¬LzF­UÃ:'# /.Ì~ :'# /. : & @

u1 & ( #$ #§ª0z)Ç0«5õ (∪i∈IAi) =

i∈I

µ(Ai).

± ­ M­UÃLÆG«3­%È.ÇÃU¯ÅÄů a­P­UÃLÄ<Æ ± ­ZHI#$ /'* # Ç0Æ 6 1 & :'#q9 * 10>?> &)6)&)(32 ÃU¯dÇ ± ªÏ²N­%Èaz ÆGÃ

P(Ω) = 1!

­8ÄÅ«L¯¶È|z)­4Ä(Ω,F , P)

­UÃ4ħª0z)Ç0«UÃ8ªUÈpÈ'­LzFn#$39?0!$#:'#9 * 10>?> &)6)&)(32 IÇ0ÆÏ#$39?0!$#9 * 10>?> &)6)& 2 ! N |Ç-¯ Ä (E, E) Æ ± ­UÃÊÈ.ªpx5­ M­UÃUÆ«ªG¬Lz)­#­4Ä

(F, T )Æ ± ­UÃU°

È.ªpxU­Ä¾ÇUÈ'Ç0zAÇQF0¯ & Æ'­"! ± ­ $Ç ± x$ÄůÐÇ ± f : E → F­UÃLÄ´HI#$ /'* > 6 #nÃU¯ 6 r & HMPp# *32 ! & 9 * 1 EN/ #=:'# ( 1 /'( #=9? *+(+& #

1 / op# *+( #:'#F

#$ (</ #9? *+(+& #HI#$ /'* > 6 #8:'#E

∀B ∈ T , x ∈ E, f(x) ∈ B ∈ E 2 2 ± ­C$Ç ± x$ÄůÐÇ ± I­LÃUÆ«ªN¬4z)­w² $ Æ ± ­UÃÊÈ.ªpx5­8Èa«ÇG¬+ªN¬L¯ z ¯Ã$ a0­L«5ÃÆ ± ­UÃÊÈ.ªpx5­nľÇUÈ.Ç0z)Ç%F0¯ & Æ ­I­UÃLÄ"ªUÈpÈ ­Lz)5­qo- *+& > 6 #7 6F2 ( 1 &)* #!

" jM 6 *+*+& op# EG/ # 6 rt10 *32 3# * op# 6 # ( # * HI#8:'# Ë o0 *+& > 6 #q 6F2 ( 1 &)* #LÍ79^1 /'*J6 #$<ÎÐ10 ! (+& 10 HI#$ /.@* > 6 #$ ~ o- 6 # /'* «33­Lz z)­LÃLQ ¦ #%mrt#$ ( 9?0 6 #%9^1 & ( :'#o / #0:'109 (32& ! & Q D : 2 |Ç0¯ÅÄ Ω Æ ± ­ ± Ã$­M¬LzF­ ± Ç ±aB¯Ð²N­ & Æ ­LzAx5Ç ± & Æ ­ #J­4Ä X

Æ ± ­84Ç ± x$ÄůÐÇ ± ²GE ± ¯¾­%ÃLÆG« Ω­4Ä#B aª0zF­LÆG«UÃ8²pª ± Ã%Æ ± ­UþÈ'ªpx5­

(F, T )!

ª (+*+& > / #4'Pp#4 : *32 #9? *X# ± Ç-ÄÊ3­ σ(X)

# ­UÃLÄvz)ªJÈaz ÆGÃÈ'­$Äů ÄÊ­=ÄÅ«L¯Ð¬4ÆIÃUÆ«Ω«3­ ± ²pª ± Ä X M­UÃLÆG«+ªN¬LzF­"!

$ ­UÃLÄ´ª0ÆNÃUÃU¯z)ªMÄÅ«L¯¾¬LÆ­ ± FG­ ± ²0«33­JÈ.ª-«z)­LÃf­ ± Ã$­ I¬4z)­UÃ

X−1(B) = ω ∈ Ω : X(ω) ∈ BÇ

BÈ'ª0«x5Ç0ÆG«4Ä# Ã$Ç0¯ÅÄ z)ªMľÇUÈ'Ç0zAÇQF0¯Ð­ T ²G­

F#Ã$Ç0¯ÅÄÃU¯ÈazF­M­ ± Ä Æ ± ­<È.ª0«4Äů¾­ & ÆG¯ z%$ ­ ± FN­ ± ²0«+­ !

6 #8!B0,?Î *32$EG/ #4 ( ,^1Ω#$ ( : 2 u ~ H / & :sr / # (+*+& > / F # ( 1

X#$ ( : 2 u ~ : 2L & #f!$10HnHI#

/ #o0 *+& > 6 #; 6F2 ( 1 &)* #-,σ(X)

9'9? * :F ( ? (+/'* # 6)6 #4HI#4 ( !$10HnHI# / #w31 / @¾(+*+& > / :'# F Q ¦ rt#$ ( ,#4EG/ # 6FEN/ #31 *+( #-, 6 rt#4 5#4H7> 6 #=H & & HM 6 :sr 2 o © #4HI#4 ( "9^# * HI# (+( ( :'#: 2L &)*´6 7o0 *+& > 6 #% 6F2 ( 1 &)* #XQ

%# /. o- *+& > 6 #$ 6F2 ( 1 &)* #$

X# (

Y,9 * #4? (6 # /'* o- 6 # /'* \: / fHI4HI#"#$+9?0!$#

F,310 ( Fpª0zF­UÃ

­ ± zAÇ0¯ÃL,^ & # 6)6 #$10 (6 MHI4HI# 6 1 & :'#f9 * 10>?> &)6)&)(32 ,m!-rt#$ (@D~@ : &)* #M & ,?9^1 /'*( 1 /'( #4 3#4H7> 6 #IHI#$ /'* > 6 #B

:'#F, 10 6 r 2 PN 6)&)(32

P(X ∈ B) = P(Y ∈ B)R QQP SM 6 #$ (& Hn9^1 *+( ( :'#8 1 ( # *EN/ #

X# (

Ymrt10 ( /'6)6 #4HI#4 ( >|#$51 & y:srt (+* #q: 2L & #$ /'*=6 #8HI4HI#

#$+9?0!$#w:'#Z9 * 10>?> &)6)&)(32 L 6 r 2 PN 6)&)(32 #4 6 1 & f # Ë 9? *+6 #LÍ EG/ #Z:'#$ 6 1 & q:'#Z9 * 10>?> &)6)&)(32 BQ ¦ rt#$ ( !$# EG/'&9^# * HI# ( :'#%9? *+6 # * :'# Ë o- *+& > 6 #7 6F2 ( 1 &)* #7:'# 6 1 &

µÍ5Q

l r 2 PN 6)&)(32 #4 6 1 & & Hn9 6)&FEG/ #-, #4;9? *+(+& ! /'6)& # * , 6 r 2 PN 6)&)(32 :'# ( 1 / 6 #$<HI10HI#4 ( : 2L & Q #J!$10 : &)(+& 10 / KM5 ( #zRÅ# ( 2 !$#$35 &)* #-,G9 /'& EG/ r &)6 Br¶P &)( :sr / #=31 / @ !$10 : &)(+& 10 S 9|1 /'*´6 r 2 PN 6)&)(32#4 6 1 & :'#:'# /. o- *+& > 6 #$B, #$ (ZEN/ # R QQP S 31 &)( o * & #9^1 /'*I( 1 /'(

B9'9? *+( #4? (~y/ #4 3#4H7> 6 #

:sr 2 o © #4HI#4 ( EG/'& ­ ± FN­ ± ²-«+­ 6 (+*+& > / :'#FQN # ( # 6)6 #9 * 109 *+&F24(32 #$ ( 9? *+(+& ! /'6)&F©4* #4HI#4 (<& (324* #$35 ( #

EG/ :F#$ (´/ #$+9?0!$#9 * 1: /'&)( RÅ!-rt#$ (@D~@ : &)* #= &

X# (

Y310 ( :'#$ÃUƯ ÄÊ­LÃ=:'#o0 *+& > 6 #$< 6F2 ( 1 &)* #$ S L# 6)6 #Br 2 10 !$#8 6 1 * J & &

Page 70: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

Ñ ""% ) & #'('(*)+$ |Ç0¯¾­ ± Ä X = (Xn)n>0

­4ÄY = (Yn)n>0

#J²N­LÆ ÃUƯ ÄÊ­LÃI²G­Caª-«U¯ÐªN¬LzF­UÃZª0zF+ª-ľÇ0¯ «3­Uà Baª0zF­LÆ«5Ãq²pª ± ÃÆ ± ­UÃÊÈ.ªpx5­F!

X­4Ä

YÃ4Ç ± Ä FNª0z)­LÃ7­ ± z)Ç0¯ à #ÃL¯­4ÄÃ$­LÆz)­ I­ ± Ä\ÃU¯2#aÈ.Ç0Æ«%ľÇ-ÆÄ k > 0

­4Ä Ä¾Ç0ÆÄk°ÊÆÈaz)­$Ä

(B1, . . . , Bk)² $ ­ ± ÃB­M¬Lz)­Là I­LÃUÆ«ªN¬4z)­UÃn²pª ± à F#§Ç ± ªMz($ Fpª0zɯÅÄÊ

P(X1 ∈ B1, . . . , Xk ∈ Bk) = P(Y1 ∈ B1, . . . , Yk ∈ Bk).

lm1 * EN/ #

X#$ (d/ #%o- *+& > 6 #7 6F2 ( 1 &)* #-,?10; 1 ( #731 / op#4 (

(X = a)6 r 2 o © #4HI#4 (

ω ∈ Ω : X(ω) = a = X−1 (a) .

%#dHI4HI#-,G &X

#$ ( / #o0 *+& > 6 #= 6F2 ( 1 &)* # *32 # 6)6 #R ~ o- 6 # /'* : R S ,G# ( & I #$ ( / & ( # * o- 6)6 # *32 # 6

EG/ # 6 !$10 EN/ #-, 10 1 ( #(X ∈ I) = X−1(I) = ω ∈ Ω : X(ω) ∈ I .l r ­LþÈ'L«+ª ± xU­n:sr / #o- *+& > 6 #7 6F2 ( 1 &)* # *32 # 6)6 # X

,. 1 (32 #E(X)

, #$ ( : 2L & #9? *

E(X) =∑

a

aP(X = a)

=∑

ω∈Ω

X(ω)P(ω).

¦ # (+( #=: 2L &)(+& 10Zmrt#$ ( o- 6 > 6 # EG/ #J: 6 #J!B0´1X

9 * #4 :M5#$ o- 6 # /'* §: / Z#4 5#4H7> 6 # &1 / : 2 10H8> * > 6 # L : 6 #d!B0 !$10 (+* &)* #-, 6 310HnHI#J#$ ( * #4Hn9 6 0! 2 #d9? * / # & (32 P * 6 #=:'#dlm#4>^#$+P / #-Q #J9 * 109 *+&F24(32 # .(+* 4HI#4HI#4 (</'(+&)6 #-,.# ("EN/'& # 2 !$#$3 &)( #% / ! / #%O C 9|1 ( O © 3#9? *+(+& ! /'6)&F©4* # /'*´6 #$o- *+& > 6 #$ 6F2 ( 1 &)* #$ , #$ (<6 z ¯ ± +ª0«L¯ÅÄÊ8²G­z%$ ­UþÈ'4«ª ± x5­w |Ç0¯¾­ ± Ä X

­4ÄY

²N­LÆ Caª0«L¯ÐªN¬LzF­Uê-z)+ªpľÇ0¯«3­UòNE ± ¯Ð­UÃJÃUÆ«zF­ )M­­UÃÊÈ.ªpx5­"Èa«+ÇN¬+ªN¬L¯ °zɯ ÃB #§­4Ä\Ã4Ç-¯Ð­ ± Ä λ

­$ĵ²N­LÆ Z«+5­Lz à & Æ ­Lz)x3Ç ± & Æ'­UÃ"!z)Ç0«UÃ=z)ªCaª-«U¯ÐªN¬LzF­fª0z)3ª-ľÇ0¯ «+­ Z = λX + µY

²GE ± ¯¾­È.ª0« È.Ç0Æ«7ľÇ0Æ.Äω ∈ Ω

#Z(ω) = λX(ω) + µY (ω)

a0L«U¯ E´­E(Z) = λE(X) + µE(Y ).

R Q Sl aª-«U¯Ðª ± x5­7:sr / #=o0 *+& > 6 # 6F2 ( 1 &)* ##$ (´/ # EN/ (+&A !B (+& 10:'#%579 * 109|#4 & 10 ~ 9 * #4 : * #:'#$

o- 6 # /'* 246 1 & P- 2 #$:'#510;#$+9 24* !$#M' & !$# (+( ##$+9 24* !$##$ (µ = E(X)

,?10;9|1-5#Var(X) = E

(

(X − µ)2)

= E(X2)− µ2

R 6 r 2 PN 6)&)(32 :'#$:'# /. # 9 * #$3 & 10 *32 /'6)( #7: / ÎÐ &)(=EN/ # 6 no- *+& > 6 #f 6F2 ( 1 &)* #X − µ

#$ ( :srt#$+9 24* !$# /'6)6 # S Ql7o- *+& !$##$ ( 31 / op#4 ( 1 (32 #

σ2 , 6 6 # (+(+* # σR EG/'& #4#$ ( 6 * 0! & #!B *+*32 #9^1- &)(+& op# S * #49 *32 5#4 @( ( 6 1 * 6 r +x3ª-«LÄÅ° Ä I5È ­q:'# 6 qo- *+& > 6 #7 6F2 ( 1 &)* #-Q

" 1 /'( #no- *+& > 6 #n 6F2 ( 1 &)* # *32 # 6)6 #fmr¶9?0JÎÐ1 * ! 2 HI#4 (7/ #f#$39 24* !$# & #%R 6 24*+& #-,s1 /6 r & (32 P * 6 #-,§9^# /'( : & op# * Pp# * S , # (n/ #o- *+& > 6 # 6F2 ( 1 &)* # EG/'& / ##$+9 24* !$#9^# /'( #w9?0ZBop1 &)*:'#Ïo0 *+& !$#-Q<lm#$9 * 109 *+&F24(32 2 10 ! 2 #$:'1 & op#4 ( (+* ##4 ( #4 : / #$;31 / *32 3# * op#:srt# & ( #4 !$#-QN 6)/ 9 *32 ! & 2 HI#4 ( , 6 rt# & ( #4 !$#%9|1 /'*"6 # Ë HI#4H7> * #PN / !5O #LÍ#4 (+* & # 6 rt# .& ( #4 !$#=9|1 /'*<6 # Ë HI#4H8> * #: * 1 &)( Í5QV h5 +@ m &<:p r# f$ *r5*r - 68n f$ r , :n f:rjm@$,nqr5 r - n$ rjp f !Ef:p r

Page 71: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

$*" #"c " ig #"i -Ò 39 24* !$#%# ( o- *+& !$#= #510 ("EN/ # 6 #$§:'# /. 9 * #4H & # * ( # * HI#$":sr / #% /'&)( #=:'# IÇDM­ ± Ä Ã%:sr / #o- *+& > 6 #7 6F2 ( 1 &)* #-QHIÏ: 2L &)( ,'9|1 /'*J( 1 /'( #4 (+& # *

k > 0RÅ# ( 31 / *32 3# * op#7:srt# .& ( #4 !$# S , 6 # IÇDM­ ± IJ $ Ç0«+²0«+­

kR * #$+9^#$! (+& op#4HI#4 ( , IÇDM­ ± ħxU­ ± ÄÅ«3n² $ Ç0«²-«+­ k

9? *

µk(X) = E(Xk)

µck(X) = E((X − µ1(X))k)

I * #$!$10'?:F ( : µ1(X)

6 rt#$+9 24* !$#-,?# ( : µc

2(X), 6 qo- *+& !$#-Q

..1 86 :;; 86 @ ;MD (+/'&)(+& op#4HI#4 ( ,s:'# /.2 o © #4HI#4 ( %1 / :'# /. o- *+& > 6 #$= 6F2 ( 1 &)* #$%310 ( ¯ ± ²NÊÈ ­ ± ²pª ± Ä Ãf &m/ # & @ÎÐ1 * HM (+& 10q10> ( #4 / #d /'*6 r / m, #§HI1: &A #´9?0 6 !$10'? & 55 !$# EN/ # 6 rt10IJ:'# 6 r¶ /'(+* #-Q ¦ # 6 =3# (+* 0: /'&)(

ÎÐ1 * HI# 6)6 #4HI#4 ( :'# 6 fHM &F©4* #7 /'& o- ( #-Q f­LÆ ;ba ± ­ I­ ± Ä Ã A

­4ÄB

Ã4Ç ± ħ²0¯ÅÄ Ã & : 2 9^#4 : ( #§ÃU¯§­4Ä Ã$­LÆz)­ I­ ± ħÃU¯

P(A ∩B) = P(A)P(B).

I8 1 ( # * EG/ r / 2 o © #4HI#4 ( :'# 9 * 10>?> &)6)&)(32 <1 / P-,B#$ (& : 2 9^#4 : ( :'# ( 1 /'( /'(+* # 2 o © #4HI#4 ( Q f­LÆ aª0«L¯ÅªG¬Lz)­Lê0zF+ª-ľÇ0¯ «+­LÃÏ«33­Lz z)­UÃ

X­4Ä

YÃ4Ç ± Äf²0¯ÅÄÊ­Uà & : 2 9|#4 : ( #$ #7ÃU¯q­4Ä

Ã$­4ÆGzF­M­ ± ħÃU¯\zF­UÃ8²N­LÆ ª «Iª-ÄůÅÇ ± ÃÃLÆG¯ aª ± ÄÊ­UÃQ# & ƯÃ$Ç ± Ä´ & ÆG¯ aª0zF­ ± ÄÊ­LÃQ#´Ã4Ç ± Ä aB«+ª0¯Ð­Là !´È'Ç0ÆG«fľÇ0ÆGÃ%¯ ± ÄÊ­L«baª0z zF­Uà I

­$ÄJ# zF­UÃfba ± ­M­ ± Ä Ã (X ∈ I)

­4Ä(Y ∈ J)

Ã4Ç ± Ä ¯ ± ²NÊÈ'­ ± ²pª ± Ä Ã !´È'Ç0ÆG«fľÇ0Æ.ÄÊ­UÃ&aª0zF­LÆ«5Ã

x­4Ä

y#§Ç ± ª

P (X ≤ x­4Ä

Y ≤ y) = P(X ≤ x)P(Y ≤ y).

RÅ 6 #n!B0: * # 6 #q9 6)/ %P 2 24* 6 9|1-3 & > 6 #-,s1 6 #$o0 *+& > 6 #$8 6F2 ( 1 &)* #$9^# / op#4 ( (+* # ~ o- 6 # /'* : %:'#$#$+9?0!$#$ EN/ # 6 !$10 EG/ #$B, 6 r & : 2 9^#4 : !$#nBrt# 9 *+& HI#f9? *%6 #7ÎÐ &)(%EN/ # 6 #$nÄÅ«L¯Ð¬LÆGÃn#4'Pp#4 : *32 #$9? *6 #$:'# /. o0 *+& > 6 #$f 6F2 ( 1 &)* #$310 (7& : 2 9|#4 : ( #$B,m!-rt#$ (@D~@ : &)* # EG/ # ( 1 /'( #4 3#4H8> 6 #I:'# 6 r / ##$ (<& : 2 9^#4 : ( :'# ( 1 /'( #4 3#4H8> 6 #7:'# 6 r¶ /'(+* # S 6 #!B0§9? *+(+& ! /'6)& # * 1 6 #$ o- *+& > 6 #$< 6F2 ( 1 &)* #$" #J9^# / op#4 ( 9 * #4 : * # EN/ r / 10H7> * # & 1 /: 2 10H7> * > 6 #q:'#7o0 6 # /'* R 6 #7!B0 (ÊC 9 &FEN/ # 24( ( !$# 6)/'& :'#o- *+& > 6 #$% 6F2 ( 1 &)* #$ ~ o0 6 # /'* n­ ± Äů&L«3­Uà S ,6 q: 2L &)(+& 10Ï#$ (d2 PN 6 #4HI#4 (%2$EN/'& o- 6 #4 ( # ~n6 q /'& o0 ( #I M f­LÆ aª0«U¯ÐªN¬LzF­UÃZª0zF+ª-ľÇ-¯«3­UÃ

X­4Ä

Y#B%aª-z)­LÆ«UÃZ²pª ± ÃnÆ ± ­ ± ÃB­M¬LzF­*E ± ¯dÇ0ƲNL°

± ÇDM¬L«+ªN¬LzF­V#Ã$Ç ± Ä & : 2 9^#4 : ( #$fÃL¯§­4ÄÃB­LÆz)­M­ ± Ä ÃL¯ #|È.Ç-ÆG«fľÇ0ÆNà x

­4Äy²pª ± Ã V

#§Ç ± ª

P(X = x­4Ä

Y = y) = P(X = x)P(Y = y).

l r & : 2 9^#4 : !$#M:'#Io0 *+& > 6 #$7 6F2 ( 1 &)* #$8#$ (/ #q 1 (+& 10 & Hn9^1 *+( ( #-,v# ( w:'#$!$10 2$EG/ #4 !$#$EG/'& #310 ( 9?0<o * & #$J#4;P 2 24* 6 |Ç0¯¾­ ± Ä X

­4ÄY

²N­LÆ caª0«L¯ÅªG¬Lz)­LÃfª0zF+ª-ľÇ0¯ «+­LÃ7¯ ± ²NÊÈ'­ ± ²pª ± ÄÊ­UÃ"! ± ª

E(XY ) = E(X)E(Y )R Q S

Var(X + Y ) = Var(X) + Var(Y )R Q Ñ S

Page 72: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

< ""% ) & #'('(*)+$ |Ç0¯¾­ ± Ä X ­4Ä

Y²N­4Æaª0«U¯ÐªN¬LzF­Uê0zF+ª-ľÇ0¯ «+­Lï ± ²NÊÈ'­ ± ²pª ± ÄÊ­Là ! zAÇ0«UÃQ# & Æ'­4zzF­Uà & Æ'­Ã4Ç-¯Ð­ ± Ä\z)­UÃ/$Ç ± x$ÄůÐÇ ± à f

­$Äg ²NE ± ¯¾­UÃ=ÃUÆ«zF­UÃ8­ ± ÃB­M¬LzF­UòG­iaª-z)­LÆ«UòG­

X­$Ä

Y#\«3­UþÈ'­3x$Äů4a0­M­ ± Ä #

f(X)­4Ä

g(Y )Ã$Ç ± Ä ¯ ± ²GÊÈ'­ ± ²Nª ± ÄÊ­UÃ"!

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°ÊÆÈaz)­$Ä(X1, . . . , Xk)

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­ ± Ã$­M¬LzF­UòG­ aª0zF­LÆG«UÃ(A1, . . . , Ak)

#Ç ± ª

P(Xi ∈ Ai(1 ≤ i ≤ k)) =∏

1≤i≤k

P(Xi ∈ Ai)

± ­ 4ªDq¯ zzF­d¯ ± E ± ¯Ð­ (Xi)i∈I²N­aª0«L¯ÅªN¬4z)­Uê0zF+ª-ľÇ0¯ «+­LÃ%­UÃLÄ\x3ÇDÈ.Ç0Ã$3­²G­aª0«L¯ÅªN¬4z)­UÃ

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3o- @

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k@¾/ 9 6 # ( #$ (/

k@¾/ 9 6 # ( :'#´o0 *+& > 6 #$ 6F2 ( 1 &)* #$

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|Ç-¯Ð­ ± Ä X1, . . . , Xk#

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B²N­LÆ ba ± ­M­ ± Ä Ã #sªEa0­+x

P(B) >0!ª9 * 10>?> &)6)&)(32 :'#

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A!$10 : &)(+& 10' # 6)6 #4HI#4 (I~

B#­UÃ4IJNE ± ¯Ð­È.ª0«

P(A|B) =P(A ∩B)

P(B).

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Page 73: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

$*" #"c " ig #"i O|Ç-¯ Ä

XÆ ± ­aª-«U¯ÐªN¬LzF­ª0zF+ª-ľÇ0¯ «3­ #­4Ä B

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µB²NE ± ¯Ð­<È.ª0«

µB(I) = P(X ∈ I|B).

I : 2L &)( :'#HI4HI# 6 rt#$+9 24* !$#!$10 : &)(+& 10' # 6)6 #:'#X

U0!3O? (B

RÅ!-rt#$ (q6 rt#$+9 24* !$#w:sr / #o- *+& > 6 #:'# 6 1 &

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B#$ ( Ë !$# EG/ #8:'#4o & #4 ( Í 6 Z9 * 10>?> &)6)&)(32 :'#8!$# (2 o © #4HI#4 ( &v6 rt10Ì5 &)(%EN/ #

B3# *32 6)& 3#-Q M ± ba ± ­ I­ ± Ä A

­UÃLÄ ¯ ± ²GÊÈ'­ ± ²Nª ± ħ²G­ B#vÃL¯­$Ä\Ã$­LÆzF­M­ ± ÄÃL¯

P(A|B) = P(A)!

± ­ aª0«L¯ÅªN¬4z)­fª0zF+ª-ľÇ0¯ «3­ X#´²N­7z)Ç0¯

µ#§­UÃLħ¯ ± ²NÊÈ'­ ± ²pª ± ÄÊ­f²N­ B

#ÃU¯§­4Ä Ã$­LÆz)­ I­ ± ħÃU¯ µB = µ!

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Èa«L¯Ã$­ È.ª-«X#

P(X = x|Y = y) = P(X = x).

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X#$ (<6 I 24*+& ##4 (+&F©4* #8:'#%o0 *+& > 6 #

t,

SX(t) =∑

k∈N

P(X = k)tk

qr¶9 *3© 6 q: 2L &)(+& 10:'#SX

,'10Ï & HnH 2 : & ( #4HI#4 (

SX(t) = E(tX)

l8 24*+& #SX

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[0, 1[Q

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E(X) = S′X(1)

E(X(X − 1)) = S ′′X(1)

E(X · · · (X − k + 1)) = S(k)X (1)

Var(X) = S ′′X(1) + S′

X(1)−(

S′X(1))

)2

Y n # porn -- m4*|Qw94 |.w .xEy

Page 74: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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X310 (

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SX+Y (t) = SX(t)SY (t).

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(Ω, P)#§Ç

Ω = Ω1 × Ω2

P(ω1, ω2) = P1(ω1)P2(ω2)

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# (X2

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X ′1(ω1, ω2) = X1(ω1)

X ′2(ω1, ω2) = X2(ω2)

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# z($ ­UþÈ'ªpx5­JÈa«+ÇN¬+ªG¬L¯zɯÃ$Ω′,F ′, P′)

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n ≥ 0

Page 75: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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k#$ (

Èa«+ÇUÈ.Ç0«4ÄůÐÇ ± ± ­Lz zF­ ~π(k)

Ql r 24( 9|#I /'& o0 ( #R HI10 (+* # *fEN/ #n!$# (+( #n9 * 10>?> &)6)&)(32 #$ ( Fpª-z)­ ~π(k) S #4: 2 !$1 /'6 # & HnH 2 : & ( #4HI#4 ( 6 #%!$1#LKM! & #4 ( :'#=9 * 109^1 *+(+& 10'? 6)&)(32 #%5 /'* &)( #4# µ # ( (+* #%: &Aµ^24* #4 ( :'#

k π(k)Q

.21/. 5C4j6 6; ; =84jA89 986 #aª0«L¯ÅªG¬Lz)­f²N­=­L« ± Ç0ÆGz zɯ§:'#%9? * H ©4(+* # p

R0 < p < 1 S ,.o- /'( 1

$op#$!9 * 10>?> &)6)&)(32p# (

0Bop#$!

9 * 10>?> &)6)&)(32q = 1− p

QM 6 #$ ( ξ0! &)6 #:'#7op1 &)*JEN/ # 6 #9 * 1: /'&)( :'#:'# /. o- *+& > 6 #$:'# "# * 1 /'6)6)&& : 2 9|#4 : ( #$B,|:'#9? * @H ©4(+* #$

p1# (

p2,'#$ (</ #o- *+& > 6 #:'# "# * 1 /'6)6)& :'#%9? * H ©4(+* #

p1p2Q

&B

#$ (</ # ( # 6)6 #o- *+& > 6 #7 6F2 ( 1 &)* #-,a10

E(B) = p

Var(B) = p(1− p)

lI 24*+& #%P 2 24* (+*+& !$#7:'#9 * 10>?> &)6)&)(32 =!$1 *+* #$+9^10 : ( #8#$ (SB(t) = (1− p) + tp

Q .21/.1 5C4j6 4 9L=6A ;

#caª0«L¯ÅªN¬4z)­ FN+ÇDM4ÄÅ«L¯ & Æ'­Z:'#f9? * H ©4(+* #pR0 < p < 1 S ,|o- /'( k

R 9|1 /'*k#4 (+& # * (+*+& ! ( #4HI#4 (

9^1- &)(+& Î S $op#$!9 * 10>?> &)6)&)(32 pk = p.(1− p)k−1 Q &G6 rt10f / #§ /'&)( # & & #´:'# o- *+& > 6 #$:'# "# * 1 /'6)6)&G& : 2 9^#4 : ( #$,

(Xn)n∈N

, ( 1 /'( #$v:'# HI4HI#9? * H ©4(+* #

p, 6 r & : & !$# :'# 6 "9 * #4H &F©4* #§:'# !$#$ "# * 1 /'6)6)&GEG/'& o- /'(

1RÅ31 &)(

G = minn ∈ N : Xn = 1 S#$ (</ #o- *+& > 6 #P 2 10H 24(+*+&FEG/ #7:'#%9? * H ©4(+* #pQ

Z lflp$ p? @ $& + ( r+ - )lp? 7 r# mon epB ( f # n*$ p m 8 ( f) +& r+bf 6< p r# f"$6 f r# - n r+nlr r p p ( (:pon , & 5*r+lm? lf %"&% (@=80bm (bk**<

Page 76: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

""% ) & #'('(*)+$ &

G#$ (</ #o0 *+& > 6 #8 6F2 ( 1 &)* #P 2 10H 24(+*+&FEG/ #7:'#%9? * H ©4(+* #

p,'10Ï

E(G) =1

p

Var(G) =1− p

p2

lI 24*+& #%P 2 24* (+*+& !$#7:'#9 * 10>?> &)6)&)(32 =:'# 6 qP 2 10H 24(+*+&FEG/ #:'#9? * H ©4(+* #p#$ (

SG(t) =pt

1− (1− p)t

#%9 * 109 *+&F24(32& Hn9^1 *+( ( #7:'# 6 6 1 & P 2 10H 24(+*+&FEG/ ##$ ("6 q /'& o- ( #-,a9'9|# 6F2 #Èa«+ÇUÈa«L¯¾4ÄÊf²N­ 'ª0«L°PÇEa®| &

X#$ (/ #fo- *+& > 6 #7P 2 10H 24(+*+&FEG/ # R EN/ # 6)6 # EG/ #831 &)( 3109? * H ©4(+* # S , EN/ # 6 EG/ #831 & #4 (%6 #$#4 (+& # * J9|1- &)(+& ÎÅ

s,t# (

uRÐ$op#$!

t < u S ,'10

P(X ∈ [t + s, u + s]|X > s) = P(X ∈ [t, u])

/'(+* #4HI#4 ( : &)( , / #o- *+& > 6 #P 2 10H 24(+*+&FEG/ #-,\x3Ç ± ²0¯ÅÄůÐÇ ± ± 3­ ~ (+* #9 6)/ dP * :'# EN/ # s, /'&)(J/ #

6 1 & P 2 10H 24(+*+&FEG/ #RÅ:'#dHI4HI#d9? * H ©4(+* # S : 2 !B 6F2 #=:'# sQ IM: &)( / 3 &?EN/ # 6 #$ 6 1 & §P 2 10H 24(+*+&FEN/ #$´310 (

Ã4ª ± à I nÇ-¯«3­4Q " |!$# (+( #%9 * 109 *+&F24(32 :'# * p1ox3ª0«+ªpx$ÄÊ4«U¯Ã$­ 6 #$ 6 1 & "P 2 10H 24(+*+&FEG/ #$J /'*"6 #$<#4 (+& # * <9|1- &)(+& ÎÅ 6 #6 #$! ( # /'* #$ (=& No &)(32n~ HI10 (+* # *EN/ #-,^ &/ #fo0 *+& > 6 #n 6F2 ( 1 &)* # ~ o0 6 # /'* *32 # 6)6 #$%9^1- &)(+& op#$=o 24*+&A # 6 9 * 109 *+&F24(32 :'# y * p1Bo; #83# * &)(@ !$# EG/ #9^1 /'*

s = 1,a!-rt#$ ( #4;ξ &)(J/ #7o0 *+& > 6 #7P 2 10H 24(+*+&FEN/ #q:'10 (

6 #%9? * H ©4(+* #7#$ (1− P(X = 0)

Q .21/. 3 5C4j6 ?6 6e@9e;

# aª0«L¯ÅªG¬Lz)­¬L¯ ± q¯Åª-z)­®:'#y9? * H ©4(+* #$n

# (pRn ∈ N

,0 < p < 1 S o0 /'( k

Rk#4 (+& # * ,

0 ≤ k ≤ n S $op#$!9 * 10>?> &)6)&)(32pk =

(

n

k

)

pk(1− p)n−k

&G6 rt10q / #§ /'&)( #§:'#no- *+& > 6 #$ 6F2 ( 1 &)* #$:'# "# * 1 /'6)6)&& : 2 9^#4 : ( #$, ( 1 /'( #$\:'# 9? * H ©4(+* #

p,(Xi)1≤i≤n

, 6 # /'* 510HnHI#Sn =

∑ni=1 Xi

#$ (</ #o0 *+& > 6 #> & _ H & 6 #8:'#%9? * H ©4(+* #$n# (

pQ

qr¶9 *3© !$# (+( # * #4HM *3EN/ #-, &)6 #$ ( & 2 :'#7op1 &)*EG/ #-,^ &B1

# (B2

310 ( :'#$=o- *+& > 6 #$%> & _ H & 6 #$:'#f9? * HI# (+* #$

(n1, p)# (

(n2, p), & : 2 9^#4 : ( #$, 6 1 *

B1 + B2#$ (=/ #qo- *+& > 6 #f> & _ H & 6 #I:'#

9? * H ©4(+* #$(n1 + n2, p)

Q " ¦ # (+( # * #4HM *3EG/ #J #=Br¶9'9 6)&FEG/ #d9?0" & 6 #$§9 * 10>?> &)6)&)(32

p:'#$´:'# /.I6 1 & §> & _ H & 6 #$" #J310 (

9?0 6 #$<HI4HI#$Q &

X#$ (</ # ( # 6)6 #o- *+& > 6 #7 6F2 ( 1 &)* #-,?10

E(X) = np

Var(X) = np(1− p)

lI 24*+& #%P 2 24* (+*+& !$#7:'#9 * 10>?> &)6)&)(32 =:'# 6 q> & _ H & 6 #8#$ (S(t) = ((1− p) + pt)n

[ f 8n -- m m'"mon(f"* 8n epbf `

n

k

´ r p kbfJm'@$66:($ p f 0lp f"* p nqm n!k!(n−k)!

Page 77: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

z)z )+ ) # % & #'('(*)+ $ P .21/. 5C4j6 6; 4j687E74

#aª0«L¯ÅªG¬Lz)­q²G­ dÇ0¯ ÃUÃ4Ç ± :'#%9? * H ©4(+* #λRλ > 0 S ,.o0 /'( k

Rk ∈ N S $op#$!9 * 10>?> &)6)&)(32

pk = e−λ λk

k! &

X#$ (</ #o- *+& > 6 #:'#&N1 & 3310:'#%9? * H ©4(+* #

λ, 10

E(X) = λ

Var(X) = λ

lI 24*+& #%P 2 24* (+*+& !$#7:'#9 * 10>?> &)6)&)(32 =:'# 6 6 1 & :'#&N1 & 3310Ï#$ (

SP (t) = eλ(t−1)

l 6 1 & :'# N1 & 3310¨#$ (n& Hn9^1 *+( ( #!B * # 6)6 #9'9? * :F ( 31 / op#4 ( !$10HnHI# Ë 6)& H &)( #LÍ;:'# 6 1 & BQN\ *# #4Hn9 6 #-,| &

µn#$ (6 6 1 & > & _ H & 6 #n:'#79? * H ©4(+* #$

n# (

λnRÅ1

λ#$ (%/ *32 # 6 9^1- &)(+& Î L µn

mrt#$ (> & #4#4 ( #4 : / : 2L & # EN/ #M &

λn ≤ 1 S , 6 1 * µnË ( #4 :®op# * +Í 6 6 1 & :'# N1 & 3310 :'#n9? * H ©4(+* #

λ,

6 1 * EG/ #n( #4 :op# *

+∞ RÐ / 5#4 6 #%9 6)/ d & Hn9 6 #9^1-3 & > 6 #n 9|1 /'*<( 1 /'(k,µn(k)→ e−λλk/k! S Q

.21/. 2 5C4j687 A 6 4 = ?;=7N\ *6 rt# 9 * #$5 & 10 Ë 6 1 &./ & ÎÅ1 * HI#LÍ5,p10n: 2 & P- #<#4fξ &)( :'# /.8(ÊC 9^#$:'# 6 1 & ,- /'& o0 (EN/ # 6 rt#4 3#4H8> 6 #

31 / @ u30!$#4 ( #$ (8/ #4 3#4H8> 6 # & 1 / / & ( # * o- 6)6 #KRÅ1 // 9 * 1G: /'&)( :sr & ( # * o- 6)6 #$B,\#4¹: & HI#4 & 10 / 9 24*+& # /'* # ~ P S QN1 /'*§/ #4 3#4H7> 6 # & :'#J!B * : & ? 6

n, 6 6 1 & / & ÎÅ1 * HI#=#$ ( !$# 6)6 # EN/'& (+(+*+& > / # ~ !3O? EG/ # 246F2 HI#4 (

:'# 6 rt#4 3#4H8> 6 # 6 qHI4HI#9 * 10>?> &)6)&)(32 , EN/'& #$ ( :'10 ! 2 PN 6 # ~1/n

QN1 /'*§/ & ( # * o- 6)6 #[a, b]

, 6 6 1 & / & ÎÐ1 * HI#J#$ ( !$# 6)6 # EN/'& (+(+*+& > / # ~ !5O? EN/ #=31 / @¾& ( # * o0 6)6 #[c, d]

,/ #§9 * 10>?> &)6)&)(32 9 * 109|1 *+(+& 10' # 6)6 # ~ 5 6 10'P / # /'* L !$# (+( #´9 * 10>?> &)6)&)(32 #$ ( :'10 ! 2 PN 6 # ~ d−c

b−a

QlM 6 mrt# .& ( #9?0d:'# 6 1 &s/ & ÎÐ1 * HI#7 /'*</ & ( # * o- 6)6 # 10;>^1 * 2 Q .21/. 5C4j6; 0; 4 ; 9 6e; 9A9e;

#aª0«U¯ÐªN¬LzF­ª0zF+ª-ľÇ-¯«3­­LÈ.Ç ± ­ ± ÄůЭLz zF­:'#I9? * H ©4(+* #λRλ > 0 S 9|1 /'* :'#4 &)(32 RÅ: 2L & # /'*

R+ S

ρ(x) =1

λe−x/λ.

&X

#$ (</ # ( # 6)6 #o- *+& > 6 #7 6F2 ( 1 &)* #-,?10

E(X) = λ

Var(X) = λ2

¦ 10HnHI# 6 #$ 6 1 & P 2 10H 24(+*+&FEN/ #$B, 6 #$ 6 1 & # 9^10 #4 (+& # 6)6 #$ o 24*+&A #4 ( 6 dÈa«+ÇUÈa«L¯¾4ÄÊ%²N­ 'ª0« PÇEaZ EG/ # 6 EG/ #31 & #4 (d6 #$ *32 # 6 <9^1- &)(+& ÎÅ

s,t# (

uRÐ$op#$!

t < u S ,?10

P(X ∈ [t + s, u + s]|X ≥ s) = P(X ∈ [t, u])

( ,!$10HnHI#M: 6 #M!B0P 2 10H 24(+*+&FEN/ #-,v!$# (+( #I9 * 109 *+&F24(32 :'# * p1oÌ!B * 0! (324*+& 3# 6 #$ 6 1 & 8# 9^1 @ #4 (+& # 6)6 #$9? * H &m6 #$ 6 1 & J:'#9 * 10>?> &)6)&)(32 /'*

R+ Q

Page 78: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

D ""% ) & #'('(*)+$l8 & H &)6 *+&)(32 #4 (+* # 6 1 & ´P 2 10H 24(+*+&FEN/ #$"# (´6 1 & §# 9^10 #4 (+& # 6)6 #$" #=Br¶ *+* ( #J9?0 6 ~ Q &

Gn#$ (§/ #

o- *+& > 6 #; 6F2 ( 1 &)* #P 2 10H 24(+*+&FEN/ #:'# 6 1 &1/n

,"z)ªyzAÇ-¯²G­Gn/n

x3Ç ± a­L« FN­ a­L«UÃz)ªÌz)Ç0¯­UÈ.Ç ± ­ ± Äů¾­Lz z)­²N­<È.ª0«+ªD 4ÄÅ«3­19|1 /'*J/ #: 2L &)(+& 109'9 * 109 *+&F2 #8:'# 6 q!$10Nop# * Pp#4 !$#f:'#$ 6 1 & d:'#9 * 10>?> &)6)&)(32 EG/ r &)6

mrt#$ ( 9?0 EG/ #$ (+& 10:srt# 9 6)& ! &)( # *"& ! & L : & 310 § & Hn9 6 #4HI#4 (<EN/ #-,G & Gε#$ ( / #o- *+& > 6 #= 6F2 ( 1 &)* #P 2 1 @

H 24(+*+&FEG/ #d:'#<9? * H ©4(+* #εÈ'­4ÄůÅÄÐ,N 6 1 *

εGεË * #$33#4H7> 6 #LÍ ~=/ #do0 *+& > 6 #d# 9^10 #4 (+& # 6)6 #=:'#"9? * H ©4(+* #

1Q

S8- cfYgd]dÂ3`+_aYehj7_a`3Â3ke .43/. [email protected] 9 6 ;<3 @ =4

l r & 2 PN 6)&)(32 :'# * p1o9|# * HI# ( :'# Iª B$Ç0«+­4« 6 n9 * 10>?> &)6)&)(32qEN/ r / #7o0 *+& > 6 #f 6F2 ( 1 &)* #È'ÇÃU¯ÅÄů4a0­Ç0Æ ± ÆGz z)­731 &)( Ë (+*3© = /.@ :'#$3 / Í:'#310#$+9 24* !$#n M |Ç0¯ÅÄ

XÆ ± ­!aª0«L¯ÅªG¬Lz)­ª0zF+ª-ľÇ-¯«3­cB aª-z)­LÆ«UÃZ²pª ± Ã

R+ #­4Ä<Ã$Ç0¯ÅÄ µ = E(X)

Ã4Ç ±­UÃÊÈ'L«+ª ± x5­"! z)Ç0«5Ã7Ç ± ª#^È.Ç-ÆG«7ľÇ-Æħ«+5­LzmÃ4ÄÅ«U¯Ðx$ÄÊ­M­ ± ÄmÈ.ÇÃL¯ Äů λ#

P(X ≥ λ) ≤ µ

λ.

R Q¶Ò S 1 &)(

Y6 f 1 / op# 6)6 #o- *+& > 6 #7 6F2 ( 1 &)* #8: 2L & #9? * .9^1 /'*<( 1 /'(

ω ∈ Ω,

Y (ω) =

0 &

X(ω) < λλ

&X(ω) ≥ λ

M 6 #$ ( ! 6 &)*dEN/ # 6 rt10 ( 1 / u+1 /'* Y ≤ X

,'!$# EG/'& #4 (+* :FF #E(Y ) ≤ E(X)

Q I * ,E(Y ) = λP(Y >

0) = λP(X ≥ λ)Q=IÏq:'10 !

P(X ≥ λ) ≤ E(Y )

λ

≤ E(X)

λ.

2

#4HM *3EN/ 10 EG/ r / #q /'(+* #7ξDH$10:sr 2 ! *+&)* # 6 r & 2 PN 6)&)(32 :'# * p1o#$ (=6 M /'& o- ( #a9|1 /'*=( 1 /'(*32 # 6 (+*+& ! ( #4HI#4 ( 9^1- &)(+& Î

λ,

P(X ≥ λµ) ≤ 1

λ.

.43/.1 [email protected] 9 6 ; l r & 2 PN 6)&)(32 :'# * p1o;#$ (J/'(+&)6 #-,aHM & =# 6)6 #7 #79|# * HI# ( 9?0:'#7HMu1 * # *=6 n9 * 10>?> &)6)&)(32qEG/ r / #

o- *+& > 6 #Z 6F2 ( 1 &)* #M51 &)( ­ ± °²N­UÃ5Ã$Ç0ÆGÃ:'#I310#$+9 24* !$#-Qv%#n9 6)/ B, &)6 *+*+& op#nÎ *32$EN/ #4HnHI#4 (8EG/ # 6 rt1031 &)( !$10.Î * 10 (32~ :'#$"o0 *+& > 6 #$d 6F2 ( 1 &)* #$J:'10 ( 10#$ ( !B9?> 6 #:'#%!B 6 ! /'6 # * #$+9 24* !$## ( o- *+& !$#-,9^1 /'*I6 #$ EG/ # 6)6 #$ 6 r & 2 PN 6)&)(32 :'# v!3O #4> C !3O # µ RÅ1 / D-,1 / ¦ O #4> C +O #4o^, : Z5P * 9'O & #& ( # * ? (+& 10? 6 # S #$ ( 51 / op#4 ( 9 6)/ J9|# * ÎÐ1 * HM ( #89^1 /'* HMu1 * # *J6 q9 * 10>?> &)6)&)(32 :srt (+* # Ë 6 1 & .Í:'# 6 rt#$ @9 24* !$#-Q

rHn er # 8n f n p r , ln f:r:f( mon f - n +ep' 8n , bf *flnqf"$58Jm n -"- *m'&"! by w | #+w %$'& )(+* , .-)$ , 0/T21,h5(m$6 .:p (r+* - 6bflf68n@ n B pD$6 ( ( f =n -"- ep r$* ( ( f p f"$ m0;$)3)ep m mop'"5:n flrDlf;$ ( f 54)6 d 798 ε ,': F - bf":r+ren f:r2%" r p? 6s 4%;qx <- y .

Page 79: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

."$ ()+$ .)+#

M |Ç0¯ÅÄX

Æ ± ­ aª0«L¯ÐªN¬LzF­nª0zF+ª-ľÇ0¯ «+­#<² $ ­UÃÊÈ'L«+ª ± x5­ µ­4Ä<²N­ aª0«U¯Ðª ± xU­ σ2 ! z)Ç0«UÃ8Ç ±ª#^È.Ç-ÆG«7ľÇ-Æħ«+5­LzmÃ4ÄÅ«U¯Ðx$ÄÊ­M­ ± ÄmÈ.ÇÃL¯ Äů λ

#

P (|X − µ| ≥ λσ) ≤ 1

λ2.

R Q S ¦ 10 & : 24* 10 6 <o- *+& > 6 #§ 6F2 ( 1 &)* #

Y = (X−µ)2Q N\ * : 2L &)(+& 10m,!$# (+( #§o0 *+& > 6 #´ 6F2 ( 1 &)* #

f9^1 /'* #$+9 24* !$#σ2 ,'# (d6 r & 2 PN 6)&)(32 :'# y * p1Bo^,?9'9 6)&FEG/ 2 # ~

Y,':'10' #7# 0! ( #4HI#4 ( Q .Q

2

l r & 2 PN 6)&)(32 :'# v!3O #4> C !5O # µ 9^# /'(72 PN 6 #4HI#4 ( 3# *32$2 ! *+&)* #Z31 / 6 ÎÐ1 * HI#M /'& o- ( #Ïm9^1 /'*( 1 /'(λ > 0

,P (|X − µ| ≥ λ) ≤ σ2

λ2.I#4Z: 2 : /'&)( & HnH 2 : & ( #4HI#4 ( :'#$ HMu+1 * (+& 10 § & H &)6 &)* #$§ /'*§6 %9 * 10>?> &)6)&)(32%EN/ #

X31 &)( Ë 6 1 &

/.@ :'#$3 / +Í%1 / Ë 6 1 & ;#4Ï:'#$331 / Í:'#310;#$+9 24* !$#I.9^1 /'*d( 1 /'(λ > 0

,

P(X ≥ µ + λ) ≤(σ

λ

)2 R Q SP(X ≤ µ− λ) ≤

λ

)2 R Q S .43/. 3 [email protected] 9 6 ; ; =84

l r & 2 PN 6)&)(32 :'# ¦ O # * 1 µ #$ (f/ # & 2 PN 6)&)(32EG/'& #ZBr¶9'9 6)&FEG/ # ( # 6)6 # EG/ # 6)6 # EG/ r ~/ #Mo- *+& > 6 # 6F2 ( 1 &)* # EG/'& 3#89 *32 3#4 ( #f51 / 6 MÎÐ1 * HI#8:sr / #q310HnHI#q:'#8o0 *+& > 6 #$:'# "# * 1 /'6)6)& ¯ ± ²NÊÈ'­ ± ²pª ± ÄÊ­UÃR 9?0MÎÅ1 * ! 2 HI#4 ( :'#HI4HI#;9? * H ©4(+* # S L &)6 #$ ( 9|1-3 & > 6 #:srt#4 :'10' # * :'#$IP 2 24* 6)& U (+& 10 ~ :'#$310HnHI#$:'#o0 *+& > 6 #$ & : 2 9|#4 : ( #$:'# 6 1 & J: &Aµs24* #4 ( #$B,?HM & 6 r & : 2 9^#4 : !$#8#$ (</ #7!$10 : &)(+& 10& Hn9^1 *+( ( #-Q M: |Ç0¯ÅÄ

X1, . . . , XnÆ ± ­JÃLÆG¯ÅÄÊ­%²N­ n

aª0«L¯ÅªN¬4z)­Uê0zF+ª-ľÇ0¯ «+­LÃ%²N­ =­L« ± Ç0Æzzɯ & : 2 9^#4 @: ( #$ #Xi

ªDIpª ± ÄvÈa«+ÇN¬+ªG¬L¯zɯÅÄÊ pi²N­8ÃLÆ.x3x$UÃMªEa­+x

0 < pi < 1#d­4Ä´Ã4Ç0¯ÅÄ

X =∑n

i=1 XizF­LÆG«8Ã4ÇL M­"!

|Ç0¯ÅÄ´ Fpª0zF­M­ ± Ä µ =∑n

i=1 piz%$ ­LþÈ'L«+ª ± xU­n²N­ X

!z)Ç0«UÃÇ ± ª#^È'Ç0ÆG«fľÇ0Æ.Ä «33­Lz

δ > 0#

P (X > (1 + δ)µ) ≤(

(1 + δ)1+δ

)µ R Q SRvN1 /'* 9 * #4 : * #!$10 5! & #4 !$#:'# 6 r & Hn9|1 *+( !$#8:'#!$# (+( # & 2 PN 6)&)(32 , &)6 !$10Go & #4 ( :'#% 1 ( # *JEG/ #

eδ <(1 + δ)1+δ 9^1 /'*%( 1 /'(

δ > 0,^# (=EG/ #8!$# (+( # EG/ (+&)(32q( #4 :op# *

06 1 * EN/ #

δ( #4 :op# *

+∞ L 9|1 /'*δ = 1

, 6 # * 9'9|1 *+( #$ ( 9'9 * 1 .& HM (+& op#4HI#4 ( :'#0.68

Q & & ,0 &µ:'#4o & #4 ( P * :s, 6 =>|1 * #< / 9 24*+& # /'* #

: 2 ! * 1 &)( # 9|10 #4 (+& # 6)6 #4HI#4 ( o &)( #$op#$!µQ SlI9 * # / op#8:'# 6 r & 2 PN 6)&)(32 :'# ¦ O # * 1 µ , > & #4 EN/ r¶035#7! 6 03 &FEG/ #-,?#$ (/ 9^# / !B 6 ! /'6 ( 1 &)* # L # 6)6 ##$ ( :'10' 2 # & ! & 9? * 31 / ! & :'#!$10Hn9 6F24(+/ :'#-Q

1 &)(t/ *32 # 6 9|1- &)(+& Î EG/ # 6 !$10 EN/ # R 1 / J9 *32 ! & 3# * 10 J!$#7!3O 1 &A/'6)(324*+& # /'* #4HI#4 ( S QHN\ *! * 1 & 35 !$#7:'# 6 fÎÅ10 ! (+& 10Ï# 9^10 #4 (+& # 6)6 #-, &)6 o & #4 (

P (X > (1 + δ)µ) = P

(

etX > et(1+δ)µ)

.

9'9 6)&FEN/ 10 6 r & 2 PN 6)&)(32 :'# * p1oM / HI#4H7> * #=: * 1 &)( RÅ /'* 6 o0 *+& > 6 # 6F2 ( 1 &)* #etX S L &)6 o & #4 (

P (X > (1 + δ)µ) ≤ E(

etX)

et(1+δ)µ.

Page 80: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

Ñ ""% ) & #'('(*)+$N1 /'*2 o0 6)/ # * D,D

E(

etX) , 1 / * #4HM *3EN/ 10 EG/ #-, 6 #$o0 *+& > 6 #$

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E(

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< epi(et−1),# ( :'10 !

P (X > (1 + δ)µ) <

∏ni=1 epi(et−1)

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Page 81: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 82: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

E '(*'#)j ( *

Page 83: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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Page 85: Introduction l'algorithmique probabiliste Philippe Duchon Version 4

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