HAL Id: inria-00070439
https://hal.inria.fr/inria-00070439
Submitted on 19 May 2006
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Integration by parts formula for locally smooth laws and applications to sensitivity computations
Vlad Bally, Marie-Pierre Bavouzet, Marouen Messaoud
To cite this version:
Vlad Bally, Marie-Pierre Bavouzet, Marouen Messaoud. Integration by parts formula for locally smooth laws and applications to sensitivity computations. [Research Report] RR-5567, INRIA. 2005, pp.54. �inria-00070439�
ISRN INRIA/RR--5567--FR+ENG
a p p o r t
d e r e c h e r c h e
Thème NUM
INSTITUT NATIONAL DE RECHERCHE EN INFORMATIQUE ET EN AUTOMATIQUE
Integration by parts formula for locally smooth laws and applications to sensitivity computations
Vlad Bally , Marie-Pierre Bavouzet and Marouen Messaoud
N° 5567
May, 12 2005
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f : Ω×R→R mpsa_ n©_]n'0¨I|Kuc!£Kc!uol
ω y → f(ω, y) v±m k n©vxb3c!m
avx³Tc'uoc'qXn©v±¦a§±c,|Kq
Di(ω) qaɨI|uMcG_
j = 1, . . . , kiRn©_ac¼§xc!¨An_aqa mpvxacqaÉnp_ac upv±_VnD_]qy mpv±ycg§±vxb3v¯n©m
f(ω, tji(ω)−), f(ω, tji(ω)+) c yvxmon)qa uoc ]qav¯n©cF?I¨I|Ku
j = 0
qa
j =ki+ 1 ª c>mompsab$cn©_]n)np_ac,uov±K_Xnr_]qympvxac4uoc'mpc'n©v¯£Kc'§¯l n©_ace§±c¨Anr_]qa
mpv±yc§±v±b$vxnDcµvxmon©m qa.vxm ]qavxnpc(A2¿ ¡ cac!qa|n©c
Γi(f) =
ki
X
j=1
f(ω, tji(ω)−)−f(ω, tji(ω)+)
+f(ω, bi(ω)−)−f(ω, ai(ω)+). ? A
4|u
f, g ∈ C1(Di)µn©_acv±qXnpc'Kupn©vx|Kq ¦Xl ]un©m¨I|Kupbsa§¥>Kv¯£Kc!m
Z
(ai,bi)
f g0(ω, y)dy= Γi(f g)− Z
(ai,bi)
f0g(ω, y)dy , ?Ù A
mp| Γi
upc'yupc'moc'qXn©mrn©_ac!|KqXn©uov±¦asynpv±|Kq |¨np_ac¦T|upac!u)npc'uob3m5´½|u'aasµn)vxn)|np_ac'u
ª
v±mpca|¨
n©_acmpvxqaKsa§±upv¯n©vxc'm5|¨
f |Ku g¿
¾0cn n, k ∈ N
¿ ¡ c·yc'qa|npc·¦Xl
Cn,k
np_ac·!§¥mom|¨%np_ac
G × B(Rn) b3c'mpsaup¦a§xc
¨Isaqa!npv±|Kqym
f : Ω×Rn→R mosa_²np_]n
Ii(f)∈ Ck(Di) i= 1, . . . , n ª _ac!upc Ii(f)(ω, y) :=f(ω, V1, . . . , Vi−1, y, Vi+1, . . . , Vn).
4|u$bsa§xnpv¯´¶vxqaac
α= (α1, . . . , αk)∈ {1, . . . , n}k ª cac!qa|n©c
∂αkf = ∂k
∂xα1. . . ∂xαk
f¿
h|Kupc!|\£c'u
ª
c ac'qy|n©c6¦Xl
Cn,k(A) n©_ac6mo]!c |¨n©_ac$¨Isaqan©v±|qam
f ∈ Cn,k
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n©_]n¨I|uc!£Kc!uol
0≤p≤k qac!£c'uol
α = (α1, . . . , αp)∈ {1, . . . , n}p
∂αpf(V1, . . . , Vn)∈L(∞)(A)¿
^_ycMT|v±qXn©m
tji, j = 1, . . . , ki
upc!aupc!mpc!qVn)mov±qasa§¥uovxn¶l¼|KvxqVnpm ¨I|u np_ac ¨Isaqy!n©vx|Kqam5n
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pi =pi(ω, x) '8- )- E(Θf(Vi)1(ai,bi)(Vi)) = E
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R
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,
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πi : Ω×R → R+ mpsa_On©_an
πi(ω, y) = 0 ¨I|u y /∈ (ai, bi) qa πi ∈ C1(Di)¿ ¡ c
mpmosab3c
Â{Å Á :
πi ∈L(∞)(A) 32 πi0 ∈L(1+)(A)
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f : Ω×Rn→R
mpsa_n©_]n
F =f(ω, V1, ..., Vn).
¡ c ac'qa|n©cM¦Xl
S(n,k)
np_acMmo]'cg|¨0n©_ac mpvxb3a§xcr¨Isyqa!npv±|Kq]§±m mpsa_ n©_an
f ∈ Cn,k
qa
S(n,k)(A) ª vx§±§T¦Tcn©_ycemo]!ce|¨np_acmpv±b$a§xcg¨Isaqan©v±|q]§±m5mpsa_n©_]n
f ∈ Cn,k(A)¿
¡ c ª
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∂ViF := ∂f
∂xi
(ω, V1, . . . , Vn) i= 1, . . . , n¿
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n vxm)moc'wVsac!qa'c>|¨upqaa|Kb
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U = (Ui)i≤n
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Ui(ω) =ui(ω, V1(ω), . . . , Vn(ω)),
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ui : Ω×Rn→R, i∈N uoc G × B(Rn)´¶b$cGmosau©¦a§±c¨Isaqan©vx|Kqam'¿ ¡ crac'qa|n©c
¦Vl P(n,k)
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n mosa_¸n©_]~n
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d |npv±'c np_]n3vx¨
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ª
c'|Kqamov±ac!un©_acmp'§¥uaup|Nasan
hU, Viπ :=
Xn i=1
πi(ω, Vi)Ui(ω)Vi(ω).
¡ cac]qacqa|
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ª
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Á I°Æ Á yy Á D:S(n,1) → P(n,0) : v¯¨ F =f(ω, V1, . . . , Vn)
n©_ac!q
DiF := ∂f
∂xi
(ω, V1(ω), . . . , Vn(ω))1Di(ω)(Vi), DF = (DiF)i≤n∈ P(n,0).
Á I Å ya Á Á yG Evx£c'q F = (F1, . . . , Fd) Fi =fi(ω, V1, . . . , Vn)∈ S(n,1)
np_ac,h§±§xv¥G£Nv±q3'|[£upv±qa'cb3n©uov·v±m
σFij =
DFi, DFj
π = Xn
p=1
πp(ω, Vp)∂pfi∂pfj(ω, V1, . . . , Vn).
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Á Å Å Å Æ T Á \ D¡ ceyc ]qac
δ:P(n,1) → S(n,0)
B
¨I|Ku
U = (Ui)1≤i≤n mosa_.n©_]n
Ui(ω) =ui(ω, V1, . . . , Vn) ª c,ac]qac δi(U) := −
∂
∂xi
(πiui) + (πiui)∂lnpi
(ω, V1, . . . , Vn), δ(U) :=
Xn i=1
δi(U).
Á Å ~Æ Á Á Å {Á ~µ Å ¿É4|u F = f(ω, V1, . . . , Vn) ∈ S(n,0)
qa
U = (ui(ω, V1, . . . , Vn))i=1,...,n ∈ P(n,0) ª
ceac]qac
[F, U]π = Xn
i=1
Γi(Ii(f ×ui)×πi×pi)
= Xn
i=1 ki
X
j=1
(f ×ui)(ω, V1, . . . , Vj−1, tji−, Vj+1, . . . , Vn)(πipi)(ω, tji−)
−(f×ui)(ω, V1, . . . , Vj−1, tji+, Vj+1, . . . , Vn)(πipi)(ω, tji+) +
Xn i=1
(f ×ui)(ω, V1, . . . , Vj−1, bi−, Vj+1, . . . , Vn)(πipi)(ω, bi−)
− Xn
i=1
(f×ui)(ω, V1, . . . , Vj−1, ai+, Vj+1, . . . , Vn)(πipi)(ω, ai+).
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πi
'8- )-
πi(ω, tji+) =πi(ω, tji−) = 0, i= 1, . . . , n, j = 1, . . . , ki
?;5A
πi(ω, ai+) =πi(ω, bi−) = 0, i= 1, . . . , n,
I
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32 U ∈ P(n,1)
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F ∈ S(n,1)
32 U ∈ P(n,1)
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i = 1, . . . , n
E(|F δi(U)|1A) + E(πi(ω, Vi)|DiF ×Ui|1A)<∞. ?I A
- E(|[F, U]π|1A)<∞ 32
E(hDF, Uiπ 1A) = E(F δ(U)1A) + E([F, U]π1A). ?: A
F-!#247 )-
E(hDF, Uiπ 1A) = E(F δ(U)1A).
Å Å kµv±qa!c
πi = 0 |Kq (ai, bi)c ª ce_]G£Kc E(hDF, Uiπ 1A)
=E(
Xn i=1
E (πi(ω, Vi)DiF ×Ui | Gi)1A)
=E 1A
Xn i=1
Z bi
ai
(πiui∂if)(ω, V1, . . . , Vi−1, y, Vi+1, . . . , Vn)pi(ω, y)dy
! .
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c|K¦yn©v±q
Z bi
ai
∂if ×(πiui)×pi
=
ki
X
j=0
Z
(tji,tji+1)
∂if ×(πiui)×pi
= Γi(Ii(f ×ui)πipi)−
ki
X
j=0
Z
(tji,tji+1)
f×(∂i(πiui)×pi+ (πiui)×∂pi))
= Γi(Ii(f ×ui)πipi)− Z bi
ai
f ×(∂i(πiui) +πiui∂lnpi)×pi.
GDl ??5A
ª
ce_]G£Kc
Z
R
(|ui∂if| πipi)(ω, V1, . . . , Vi−1, y, Vi+1, . . . , Vn)dy <∞, Z
R
(|f(∂i(πiui) +πiui∂lnpi)| ×pi)(ω, V1, . . . , Vi−1, y, Vi+1, . . . , Vn)dy <∞,
¨I|Ku)§±b$|Kmnc!£c'uol
ω∈A¿Dkµ|¼n©_ace¦|[£Kcv±qXn©c!Ku©§±mb3>cmoc'qamoc¿kNv±qa!c
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ª
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ª
c§xmp|¼|K¦µnvxq
E (|Γi(Ii(f ×ui)πipi)|1A)<∞ mo|$np_]n E (|[F, U]π| 1A)<∞¿
frmpvxqa¼n©_acac]qavxnpv±|Kq.|¨
pi ª
c,!|Kb$c¦]8>6n©|c yc'nnpv±|Kqym qa
ª
c|K¦yn©v±q
Z bi
ai
(πiui∂if)(ω, V1, . . . , Vi−1, y, Vi+1, . . . , Vn)pi(ω, y)dy
= E(F δi(U)| Gi) + Γi(Ii(f ×ui)πipi).
qycemosab$mr|[£c'u
i qa.n©_acauo|µ|¨vxm'|Kb$a§±cn©c¿
Å Å Ia Â
Q∈ S(n,1)(A) /0-"'8- 7& 8
E 1A (|πiQ|+|∂Vi(πiQ)|)1+η
<∞, i= 1, . . . , n , ?:5A
9(, η >0 -) 6 F ∈ S(n,1)(A) U ∈ P(n,1)(A)+ @-
E (QhDF, Uiπ1A) = E (F δ(Q U)1A) + E ([F, Q U] 1A) . ?: A