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49 matches found
I: 06, 72-162, LNM 39 (1967)
MEYER, Paul-André
Intégrales stochastiques I--IV (4 talks) (Martingale theory, Stochastic calculus)
This series presents an expanded exposition of the celebrated paper of Kunita-Watanabe (Nagoya Math. J. 30, 1967) on square integrable martingales. The filtration is assumed to be free from fixed times of discontinuity, a restriction lifted in the modern theory. A new feature is the definition of the second increasing process associated with a square integrable martingale (a square bracket'' in the modern terminology). In the second talk, stochastic integrals are defined with respect to local martingales (introduced from Ito-Watanabe, Ann. Inst. Fourier, 15, 1965), and the general integration by parts formula is proved. Also a restricted class of semimartingales is defined and an Ito formula'' for change of variables is given, different from that of Kunita-Watanabe. The third talk contains the famous Kunita-Watanabe theorem giving the structure of martingale additive functionals of a Hunt process, and a new proof of Lévy's description of the structure of processes with independent increments (in the time homogeneous case). The fourth talk deals mostly with Lévy systems (Motoo-Watanabe, J. Math. Kyoto Univ., 4, 1965; Watanabe, Japanese J. Math., 36, 1964)
Comment: This paper was a step in the development of stochastic integration. Practically every detail of it has been reworked since, starting with Doléans-Dade-Meyer 409. Note a few corrections in Meyer 312
Keywords: Square integrable martingales, Angle bracket, Stochastic integrals
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II: 07, 123-139, LNM 51 (1968)
SAM LAZARO, José de
Sur les moments spectraux d'ordre supérieur (Second order processes)
The essential result of the paper (Shiryaev, Th. Prob. Appl., 5, 1960; Sinai, Th. Prob. Appl., 8, 1963) is the definition of multiple stochastic integrals with respect to a second order process whose covariance satisfies suitable spectral properties
Keywords: Spectral representation, Multiple stochastic integrals
Nature: Exposition
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III: 12, 160-162, LNM 88 (1969)
MEYER, Paul-André
Rectification à des exposés antérieurs (Markov processes, Martingale theory)
Corrections are given to the talk 202 by Cartier, Meyer and Weil and to the talk 106 by Meyer
Comment: This note introduces Walsh's fork'', the well-known strong Markov process whose dual is not strong Markov
Keywords: Time reversal, Stochastic integrals
Nature: Correction
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IV: 09, 77-107, LNM 124 (1970)
Intégrales stochastiques par rapport aux martingales locales (Martingale theory, Stochastic calculus)
This is a continuation of Meyer 106, with a new complete exposition of the theory, and two substantial improvements: the filtration is general (while in 106 it was assumed free of fixed times of discontinuity) and the definition of semimartingales is the modern one (while in 106 they were the special semimartingales of nowadays). The change of variables formula is given in its full generality
Comment: The results of this paper have become classical, and are reproduced almost literally in Meyer 1017
Keywords: Local martingales, Stochastic integrals, Change of variable formula
Nature: Original
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V: 14, 141-146, LNM 191 (1971)
Intégrales stochastiques par rapport à une famille de probabilités (Stochastic calculus)
Given a family of probability laws on the same space, construct versions of stochastic integrals which do not depend on the law
Comment: Expanded by Stricker-Yor, Calcul stochastique dépendant d'un paramètre, Z. für W-theorie, 45, 1978
Keywords: Stochastic integrals
Nature: Original
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X: 03, 24-39, LNM 511 (1976)
JACOD, Jean; MÉMIN, Jean
Un théorème de représentation des martingales pour les ensembles régénératifs (Martingale theory, Markov processes, Stochastic calculus)
The natural filtration of a regenerative set $M$ is that of the corresponding age process''. There is a natural optional random measure $\mu$ carried by the right endppoints of intervals contiguous to $M$, each endpoint carrying a mass equal to the length of its interval. Let $\nu$ be the previsible compensator of $\mu$. It is shown that, if $M$ has an empty interior the martingale measure $\mu-\nu$ has the previsible representation property in the natural filtration
Comment: Martingales in the filtration of a random set (not necessarily regenerative) have been studied by Azéma in 1932. In the case of the set of zeros of Brownian motion, the martingale considered here is the second Azéma's martingale'' (not the well known one which has the chaotic representation property)
Keywords: Regenerative sets, Renewal theory, Stochastic integrals, Previsible representation
Nature: Original
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X: 17, 245-400, LNM 511 (1976)
MEYER, Paul-André
Un cours sur les intégrales stochastiques (6 chapters) (Stochastic calculus, Martingale theory, General theory of processes)
This is a systematic exposition of the theory of stochastic integration with respect to semimartingales, with the exception of stochastic differential equations. Chapter I is devoted to a quick exposition of the general theory of processes, and of the trivial stochastic integral with respect to a process of finite variation. Chapter II is the Kunita-Watanabe theory of square integrables martingales, angle and square bracket, stable subspaces, compensated sums of jumps, and the corresponding $L^2$ theory of stochastic integration. Chapter III studies a restricted class of semimartingales and introduces the Ito formula, with its celebrated applications due to Watanabe, to Brownian motion and the Poisson process. Chapter IV localizes the theory and gives the general definitions of semimartingales and special semimartingales, and studies the stochastic exponential, multiplicative decomposition. It also sketches a theory of multiple stochastic integrals. Chapter V deals with the application of the spaces $H^1$ and $BMO$ to the theory of stochastic integration, and to martingales inequalities (it contains the extension to continuous time of Garsia's Fefferman implies Davis implies Burkholder'' approach). Chapter VI contains more special topics: Stratonovich integrals, Girsanov's theorem, local times, representation of elements of $BMO$
Comment: This set of lectures was well circulated in its time, an intermediate stage between a research paper and a polished book form. See also 1131. Now the material can be found in many books
Keywords: Increasing processes, Stable subpaces, Angle bracket, Square bracket, Stochastic integrals, Optional stochastic integrals, Previsible representation, Change of variable formula, Semimartingales, Stochastic exponentials, Multiplicative decomposition, Fefferman inequality, Davis inequality, Stratonovich integrals, Burkholder inequalities, $BMO$, Multiple stochastic integrals, Girsanov's theorem
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X: 19, 414-421, LNM 511 (1976)
PRATELLI, Maurizio
Espaces fortement stables de martingales de carré intégrable (Martingale theory, Stochastic calculus)
This paper studies closed subspaces of the Hilbert space of square integrable martingales which are stable under optional stochastic integration (see 1018)
Keywords: Stable subpaces, Square integrable martingales, Stochastic integrals, Optional stochastic integrals
Nature: Original
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X: 20, 422-431, LNM 511 (1976)
YAN, Jia-An; YOEURP, Chantha
Représentation des martingales comme intégrales stochastiques des processus optionnels (Martingale theory, Stochastic calculus)
An attempt to build a theory similar to the previsible representation property with respect to a basic local martingale, but using the optional stochastic integral instead of the standard one
Comment: Apparently this optional representation property'' has not been used since
Keywords: Optional stochastic integrals
Nature: Original
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X: 22, 481-500, LNM 511 (1976)
YOR, Marc
Sur les intégrales stochastiques optionnelles et une suite remarquable de formules exponentielles (Martingale theory, Stochastic calculus)
This paper contains several useful results on optional stochastic integrals of local martingales and semimartingales, as well as the first occurence of the well-known formula ${\cal E}(X)\,{\cal E}(Y)={\cal E}(X+Y+[X,Y])$ where ${\cal E}$ denotes the usual exponential of semimartingales. Also, the s.d.e. $Z_t=1+\int_0^t Z_sdX_s$ is solved, where $X$ is a suitable semimartingale, and the integral is an optional one. The Lévy measure of a local martingale is studied, and used to rewrite the Ito formula in a form that involves optional integrals. Finally, a whole family of exponentials'' is introduced, interpolating between the standard one and an exponential involving the Lévy measure, which was used by Kunita-Watanabe in a Markovian set-up
Keywords: Optional stochastic integrals, Stochastic exponentials, Lévy systems
Nature: Original
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XI: 26, 390-410, LNM 581 (1977)
JACOD, Jean
Sur la construction des intégrales stochastiques et les sous-espaces stables de martingales (Martingale theory)
This paper develops the theory of stochastic integration (previsible and optional) with respect to local martingales starting from the particular case of continuous local martingales, and from the explicit description of the jumps of a local martingale (1121, 1129). Then the theory of stable subspaces of $H^1$ (instead of the usual $H^2$) is developed, as well as the stochastic integral with respect to a random measure. A characterization is given of the jump process of a semimartingale. Then previsible stochastic integrals for semimartingales are given a maximal extension, and optional integrals for semimartingales (differing as usual from those for martingales) are defined
Comment: On the maximal extension of the stochastic integral $H{\cdot}X$ with $H$ previsible, see also Jacod, Calcul stochastique et problèmes de martingales, Springer 1979. Other, equivalent, definitions are given in 1415, 1417, 1424 and 1530
Keywords: Stochastic integrals, Optional stochastic integrals, Random measures, Semimartingales
Nature: Original
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XI: 29, 418-434, LNM 581 (1977)
LÉPINGLE, Dominique
Sur la représentation des sauts des martingales (Martingale theory)
The problem discussed in this paper consists in decomposing into two parts a local martingale, so that one part has its jumps contained in a given thin optional set $D$ and the other one is continuous on $D$. The main theorem of 1121 is proved independently as an important technical tool
Keywords: Local martingales, Jumps, Optional stochastic integrals
Nature: Original
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XI: 30, 435-445, LNM 581 (1977)
MAISONNEUVE, Bernard
Une mise au point sur les martingales locales continues définies sur un intervalle stochastique (Martingale theory)
The following definition is given of a continuous local martingale $M$ on an open interval $[0,T[$, for an arbitrary stopping time $T$: two sequences are assumed to exist, one of stopping times $T_n\uparrow T$, one $(M_n)$ of continuous martingales, such that $M=M_n$ on $[0,T_n[$. Stochastic integration is studied, and the change of variable formula is extended. It is proved that the set where the limit $M_{T-}$ exists and is finite is a.s. the same as that where $\langle M,M\rangle_T<\infty$, a result whose proof under the usual definition (i.e., assuming $T$ is previsible) was not clear
Keywords: Martingales on a random set, Stochastic integrals
Nature: Original
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XI: 31, 446-481, LNM 581 (1977)
MEYER, Paul-André
Notes sur les intégrales stochastiques (Martingale theory)
This paper contains six additions to 1017. Chapter~I concerns Hilbert space valued martingales, following Métivier, defining in particular their operator valued brackets and the corresponding stochastic integrals. Chapter~II gives a new proof (due to Yan, and now classical) of the basic result on the structure of local martingales. Chapter~III is a theorem of Herz (and Lépingle in continuous time) on the representation of $BMO$ which corresponds to the maximal'' definition of $H^1$. Chapter~IV states that, if $(B_t)$ is a $BMO$ martingale and $(X_t)$ is a martingale bounded in $L^p$, then $\sup_t X^{\ast}_t |B_{\infty}-B_t|$ is also in $L^p$ with a norm controlled by that of $X$ ($1< p<\infty$; there is at least a wrong statement about $p=1$ at the bottom of p. 470). This result can be interpreted as $L^p$ boundedness of the commutator of two operators: multiplication by an element of $BMO$, and stochastic integration by a bounded previsible process. Chapter~V (again on $BMO$) has a wrong proof, and seems to be still an open problem. Chapter~VI consists of small additions and corrections, and in particular acknowledges the priority of P.W.~Millar for useful results on local times
Comment: Three errors are corrected in 1248 and 1249
Keywords: Stochastic integrals, Hilbert space valued martingales, Operator stochastic integrals, $BMO$
Nature: Original
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XI: 36, 518-528, LNM 581 (1977)
YOR, Marc
Sur quelques approximations d'intégrales stochastiques (Martingale theory)
The investigation concerns the limit of several families of Riemann sums, converging to the Ito stochastic integral of a continuous process with respect to a continuous semimartingale, to the Stratonovich stochastic integral, or to the Stieltjes integral with respect to the bracket of two continuous semimartingales. The last section concerns the stochastic integral of a differential form
Comment: Stratonovich stochastic integrals of differential forms have been extensively studied in the context of stochastic differential geometry: see among others Ikeda-Manabe Publ. RIMS, Kyoto Univ. 15, 1979; Bismut, Mécanique Aléatoire, Springer LNM~866, 1981; Meyer 1505
Keywords: Stochastic integrals, Riemann sums, Stratonovich integrals
Nature: Original
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XII: 20, 180-264, LNM 649 (1978)
BISMUT, Jean-Michel
Contrôle des systèmes linéaires quadratiques~: applications de l'intégrale stochastique (Control theory)
(To be completed) This is a set of lectures in control theory, which makes use of refined techniques in stochastic integration. It should be reviewed in detail
Comment: To be completed
Keywords: Optional stochastic integrals
Nature: Original
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XII: 48, 739-739, LNM 649 (1978)
MEYER, Paul-André
Correction à Retour sur la représentation de $BMO$'' (Martingale theory)
Two errors in 1131 are corrected
Keywords: Stochastic integrals, $BMO$
Nature: Correction
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XII: 49, 739-739, LNM 649 (1978)
MEYER, Paul-André
Correction à Caractérisation de $BMO$ par un opérateur maximal'' (Martingale theory)
Corrects an error in 1131
Keywords: Stochastic integrals, $BMO$
Nature: Correction
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XII: 51, 740-740, LNM 649 (1978)
MEYER, Paul-André
Correction à Sur un théorème de C. Stricker'' (Stochastic calculus)
Fills a gap in a proof in 1132
Keywords: Stochastic integrals
Nature: Correction
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XII: 56, 757-762, LNM 649 (1978)
MEYER, Paul-André
Inégalités de normes pour les intégrales stochastiques (Stochastic calculus)
Inequalities of the following kind were introduced by Émery: $$\|X.M\|_{H^p}\le c_p \| X\|_{S^p}\,\| M\|$$ where the left hand side is a stochastic integral of the previsible process $X$ w.r.t. the semimartingale $M$, $S^p$ is a supremum norm, and the norm $H^p$ for semimartingales takes into account the Hardy space norm for the martingale part and the $L^p$ norm of the total variation for the finite variation part. On the right hand side, Émery had used a norm called $H^{\infty}$. Here a weaker $BMO$-like norm for semimartingales is suggested
Keywords: Stochastic integrals, Hardy spaces
Nature: Original
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XIII: 22, 250-252, LNM 721 (1979)
CHOU, Ching Sung
Caractérisation d'une classe de semimartingales (Martingale theory, Stochastic calculus)
The class of semimartingales $X$ such that the stochastic integral $J\,.\,X$ is a martingale for some nowhere vanishing previsible process $J$ is a natural class of martingale-like processes. Local martingales are exactly the members of this class which are special semimartingales
Comment: This class has found recently a natural use in mathematical finance (Delbaen-Schachermayer 1997)
Keywords: Local martingales, Stochastic integrals
Nature: Original
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XIII: 23, 253-259, LNM 721 (1979)
SPILIOTIS, Jean
Sur les intégrales stochastiques de L.C. Young (Stochastic calculus)
This is a partial exposition of a theory of stochastic integration due to L.C. Young (Advances in Prob. 3, 1974)
Keywords: Stochastic integrals
Nature: Exposition
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XIII: 35, 407-426, LNM 721 (1979)
YOR, Marc
En cherchant une définition naturelle des intégrales stochastiques optionnelles (Stochastic calculus)
While the stochastic integral of a previsible process is a very natural object, the optional (compensated) stochastic integral is somewhat puzzling: it concerns martingales only, and depends on the probability law. This paper sketches a pedagogical'' approach, using a version of Fefferman's inequality for thin processes to characterize those thin processes which are jump processes of local martingales. The results of 1121, 1129 are easily recovered. Then an attempt is made to extend the optional integral to semimartingales
Keywords: Optional stochastic integrals, Fefferman inequality
Nature: Original
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XIII: 36, 427-440, LNM 721 (1979)
YOR, Marc
Les filtrations de certaines martingales du mouvement brownien dans ${\bf R}^n$ (Brownian motion)
The problem is to study the filtration generated by real valued stochastic integrals $Y=\int_0^t(AX_s, dX_s)$, where $X$ is a $n$-dimensional Brownian motion, $A$ is a $n\times n$-matrix, and $(\,,\,)$ is the scalar product. If $A$ is the identity matrix we thus get (squares of) Bessel processes. If $A$ is symmetric, we can reduce it to diagonal form, and the filtration is generated by a Brownian motion, the dimension of which is the number of different non-zero eigenvalues of $A$. In particular, this dimension is $1$ if and only if the matrix is equivalent to $cI_r$, a diagonal with $r$ ones and $n-r$ zeros. This is also (even if the symmetry assumption is omitted) the only case where $Y$ has the previsible representation property
Comment: Additional results on the same subject appear in 1545 and in Malric Ann. Inst. H. Poincaré 26 (1990)
Keywords: Stochastic integrals
Nature: Original
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XIII: 54, 620-623, LNM 721 (1979)
MEYER, Paul-André
Caractérisation des semimartingales, d'après Dellacherie (Stochastic calculus)
This short paper contains the proof of a very important theorem, due to Dellacherie (with the crucial help of Mokobodzki for the functional analytic part). Namely, semimartingales are exactly the processes which give rise to a nice vector measure on the previsible $\sigma$-field, with values in the (non locally convex) space $L^0$. It is only fair to say that this direction was initiated by Métivier and Pellaumail, and that the main result was independently discovered by Bichteler, Ann. Prob. 9, 1981)
Comment: An important lemma which simplifies the proof and has other applications is given by Yan in 1425
Keywords: Semimartingales, Stochastic integrals
Nature: Exposition
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XIV: 03, 18-25, LNM 784 (1980)
CAIROLI, Renzo
Sur l'extension de la définition d'intégrale stochastique (Several parameter processes)
A result of Wong-Zakai (Ann. Prob. 5, 1977) extending the definition of the two kinds of stochastic integrals relative to the Brownian sheet is generalized to cover the case of stochastic integration relative to martingales, or strong martingales
Comment: A note at the end of the paper suggests some improvements
Keywords: Stochastic integrals, Brownian sheet
Nature: Original
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XIV: 15, 128-139, LNM 784 (1980)
CHOU, Ching Sung; MEYER, Paul-André; STRICKER, Christophe
Sur l'intégrale stochastique de processus prévisibles non bornés (Stochastic calculus)
The standard theory of stochastic integration deals with locally bounded previsible processes. The natural definition of the stochastic integral $H.X$ of a previsible process $H$ w.r.t. a semimartingale $X$ consists in assuming the existence of some decomposition $X=M+A$ such that $H.M$ exists in the martingale sense, and $H.A$ in the Stieltjes sense, and then defining $H.X$ as their sum. This turns out to be a very awkward definition. It is shown here to be equivalent to the following one: truncating $H$ at $n$, the standard stochastic integrals $H_n.X$ converge in the topology of semimartingales. This is clearly invariant under changes of law. A counterexample shows that integrability may be lost if the filtration is enlarged
Comment: See also 1417. This is a synthesis of earlier work, much of which is due to Jacod, Calcul Stochastique et Problèmes de Martingales, Lect. Notes in M. 714. The contents of this paper appeared in book form in Dellacherie-Meyer, Probabilités et Potentiel B, Chap. VIII, \S3. An equivalent definition is given by L. Schwartz in 1530, using the idea of formal semimartingales''. For further steps in the same direction, see Stricker 1533
Keywords: Stochastic integrals
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XIV: 17, 148-151, LNM 784 (1980)
YAN, Jia-An
Remarques sur l'intégrale stochastique de processus non bornés (Stochastic calculus)
It is shown how to develop the integration theory of unbounded previsible processes (due to Jacod 1126), starting from the elementary definition considered awkward'' in 1415
Comment: Another approach to those integrals is due to L. Schwartz, in his article 1530 on formal semimartingales
Keywords: Stochastic integrals
Nature: Original
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XIV: 18, 152-160, LNM 784 (1980)
ÉMERY, Michel
Compensation de processus à variation finie non localement intégrables (General theory of processes, Stochastic calculus)
First an example is given of a local martingale $M$ and an unbounded previsible process $H$ such that $H.M$ exists in the sense of 1126 and 1415, but is not a local martingale. This leads to a natural enlargement of the class of local martingales, which turns out to be the same suggested by Chou in 1322 under the name of class $(\Sigma_m)$. Once the class has been so extended, the operation of previsible compensation can be extended to a class of processes with finite variation, but not locally integrable variation, and the class of special semimartingales can be also enlarged
Comment: This class has found recently a natural use in mathematical finance (Delbaen-Schachermayer 1997). Using the language of L. Schwartz 1530, it is the intersection of the set of (usual) semimartingales with the set of formal martingales
Keywords: Local martingales, Stochastic integrals, Compensators
Nature: Original
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XIV: 19, 161-172, LNM 784 (1980)
JACOD, Jean
Intégrales stochastiques par rapport à une semi-martingale vectorielle et changements de filtration (Stochastic calculus, General theory of processes)
Given a square integrable vector martingale $M$ and a previsible vector process $H$, the conditions implying the existence of the (scalar valued) stochastic integral $H.M$ are less restrictive than the existence of the componentwise'' stochastic integral, unless the components of $M$ are orthogonal (this result was due to Galtchouk, 1975). The theory of vector stochastic integrals, though parallel to the scalar theory, requires a careful theory given in this paper
Comment: Another approach, yielding an equivalent definition, is followed by L. Schwartz in his article 1530 on formal semimartingales
Keywords: Semimartingales, Stochastic integrals
Nature: Original
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XIV: 24, 209-219, LNM 784 (1980)
PELLAUMAIL, Jean
Remarques sur l'intégrale stochastique (Stochastic calculus)
This is an exposition of stochastic integrals and stochastic differential equations for Banach space valued processes along the lines of Métivier-Pellaumail Stochastic Integration (1980), the class of semimartingales being defined by the Métivier-Pellaumail inequality (1413)
Keywords: Stochastic integrals, Stochastic differential equations, Métivier-Pellaumail inequality
Nature: Exposition
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XIV: 25, 220-222, LNM 784 (1980)
YAN, Jia-An
Caractérisation d'ensembles convexes de $L^1$ ou $H^1$ (Stochastic calculus, Functional analysis)
This is a new and simpler approach to the crucial functional analytic lemma in 1354 (the proof that semimartingales are the stochastic integrators in $L^0$). That is, given a convex set $K\subset L^1$ containing $0$, find a condition for the existence of $Z>0$ in $L^\infty$ such that $\sup_{X\in K}E[ZX]<\infty$. A similar result is discussed for $H^1$ instead of $L^1$
Comment: This lemma, instead of the original one, has proved very useful in mathematical finance
Keywords: Semimartingales, Stochastic integrals, Convex functions
Nature: Original
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XIV: 26, 223-226, LNM 784 (1980)
YAN, Jia-An
Remarques sur certaines classes de semimartingales et sur les intégrales stochastiques optionnelles (Stochastic calculus)
A class of semimartingales containing the special ones is introduced, which can be intrinsically decomposed into a continuous and a purely discontinuous part. These semimartingales have not too large totally inaccessible jumps''. In the second part of the paper, a non-compensated optional stochastic integral is defined, improving the results of Yor 1335
Keywords: Semimartingales, Optional stochastic integrals
Nature: Original
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XIV: 28, 249-253, LNM 784 (1980)
YOEURP, Chantha
Sur la dérivation des intégrales stochastiques (Stochastic calculus)
The following problem is discussed: under which conditions do ratios of the form $\int_t^{t+h} H_s\,dM_s/(M_{t+h}-M_t)$ converge to $H_t$ as $h\rightarrow 0$? It is shown that positive results due to Isaacson (Ann. Math. Stat. 40, 1979) in the Brownian case fail in more general situations
Keywords: Stochastic integrals
Nature: Original
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XIV: 47, 489-495, LNM 784 (1980)
CAIROLI, Renzo
Intégrale stochastique curviligne le long d'une courbe rectifiable (Several parameter processes)
The problem is to define stochastic integrals $\int_{\partial A} \phi\,\partial_1W$ where $W$ is the Brownian sheet, $\phi$ is a suitable process, and $A$ a suitable domain of the plane with rectifiable boundary
Keywords: Stochastic integrals, Brownian sheet
Nature: Original
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XV: 01, 1-5, LNM 850 (1981)
FERNIQUE, Xavier
Sur les lois de certaines intégrales associées à des mouvements browniens (Brownian motion)
Let $(Z_n)$ be a sequence of independent standard Brownian motions. Define by induction a sequence of processes $U_k$ by $U_0=Z_0$, $U_k(t)=\int_0^tU_{k-1}(s)dZ_k(s)$. Let $g_k(x)$ be the density of the random variable $U_k(1)$. Then the decrease at infinity of $g_k(x)$ is of the order $\exp(-C|x|^{\alpha})$ with $\alpha=2/(k+1)$ (slightly incorrect statement, see the paper for details)
Keywords: Iterated stochastic integrals
Nature: Original
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XV: 05, 44-102, LNM 850 (1981)
MEYER, Paul-André
Géométrie stochastique sans larmes (Stochastic differential geometry)
Brownian motion in manifolds has been studied for many years; Ito had very early defined parallel transport along random paths, and Dynkin had extended it to tensors; Malliavin had introduced many geometric ideas into the theory of stochastic differential equations, and interest had been aroused by the Malliavin Calculus'' in the early eighties. The main topic of the present paper (or rather exposition: the paper contains definitions, explanations, but practically no theorems) is continuous semimartingales in manifolds, following L.~Schwartz (LN 780, 1980), but with additional features: an indication of J.M.~Bismut hinting to a definition of continuous martingales in a manifold, and the author's own interest on the forgotten intrinsic definition of the second differential $d^2f$ of a function. All this fits together into a geometric approach to semimartingales, and a probabilistic approach to such geometric topics as torsion-free connexions
Comment: A short introduction by the same author can be found in Stochastic Integrals, Springer LNM 851. The same ideas are expanded and presented in the supplement to Volume XVI and the book by Émery, Stochastic Calculus on Manifolds
Keywords: Semimartingales in manifolds, Martingales in manifolds, Transfer principle, Stochastic differential equations, Stochastic integrals, Stratonovich integrals
Nature: Original
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XV: 09, 143-150, LNM 850 (1981)
FÖLLMER, Hans
Calcul d'Ito sans probabilités (Stochastic calculus)
It is shown that if a deterministic continuous curve has a quadratic variation'' in a suitable sense (which however depends explicitly on a nested sequence of time subdivisions, for example the standard dyadic one), then it satisfies a deterministic Ito formula'' when composed with a twice differentiable function. Thus the only place where probability really appears in the derivation of Ito's formula is in the fact that, given any sequence of subdivisions, almost every path of a semimartingale admits a quadratic variation relative to this sequence (though no path may exist which has a quadratic variation relative to all sequences)
Comment: This subject is developed by T. Lyons' work on differential equations driven by non-smooth functions (in Rev. Math. Iberoamericana 14, 1998)
Keywords: Stochastic integrals, Change of variable formula, Quadratic variation
Nature: Original
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XV: 28, 388-398, LNM 850 (1981)
SPILIOTIS, Jean
Sur les travaux de Krylov en théorie de l'intégrale stochastique (Martingale theory)
The well-known work of Malliavin deals with the existence of smooth densities for solutions of stochastic differential equations with smooth coefficients satisfying a hypoellipticity condition. N.V.~Krylov's earlier work (among many papers see Izvestija Akad Nauk, 38, 1974, and Krylov's book Controlled Diffusion processes, Springer 1980) dealt with the existence of densities for several dimensional stochastic integrals with measurable bounded integrands, satisfying an ellipticity condition. It is a puzzling fact that nobody ever succeeded in unifying these results. Krylov's method depends on results of the Russian school on Monge-Ampère equations (see Pogorelov The Minkowski Multidimensional Problem, 1978). This exposition attempts, rather modestly, to explain in the seminar's language what it is all about, and in particular to show the place where a crucial lemma on convex functions is used
Keywords: Stochastic integrals, Existence of densities
Nature: Exposition
Retrieve article from Numdam
XV: 29, 399-412, LNM 850 (1981)
YOEURP, Chantha
Sur la dérivation stochastique au sens de Davis (Stochastic calculus, Brownian motion)
The problem is that of estimating $H_t$ from a knowledge of the process $\int H_sdX_s$, where $X_t$ is a continuous (semi)martingale, as a limit of ratios of the form $\int_t^{t+\alpha} H_sdX_s/(X_{t+\alpha}-X_t)$, or replacing $t+\alpha$ by suitable stopping times
Comment: The problem was suggested and partially solved by Mark H.A. Davis (Teor. Ver. Prim., 20, 1975, 887--892). See also 1428
Keywords: Stochastic integrals
Nature: Original
Retrieve article from Numdam
XV: 30, 413-489, LNM 850 (1981)
SCHWARTZ, Laurent
Les semi-martingales formelles (Stochastic calculus, General theory of processes)
This is a natural development of the 1--1correspondence between semimartingales and $\sigma$-additive $L^0$-valued vector measures on the previsible $\sigma$-field, which satisfy a suitable boundedness property. What if boundedness is replaced by a $\sigma$-finiteness property? It turns out that these measures can be represented as formal stochastic integrals $H{\cdot} X$ where $X$ is a standard semimartingale, and $H$ is a (finitely valued, but possibly non-integrable) previsible process. The basic definition is quite elementary: $H{\cdot}X$ is an equivalence class of pairs $(H,X)$, where two pairs $(H,X)$ and $(K,Y)$ belong to the same class iff for some (hence for all) bounded previsible process $U>0$ such that $LH$ and $LK$ are bounded, the (usual) stochastic integrals $(UH){\cdot}X$ and $(UK){\cdot}Y$ are equal. (One may take for instance $U=1/(1{+}|H|{+}|K|)$.)\par As a consequence, the author gives an elegant and pedagogical characterization of the space $L(X)$ of all previsible processes integrable with respect to $X$ (introduced by Jacod, 1126; see also 1415, 1417 and 1424). This works just as well in the case when $X$ is vector-valued, and gives a new definition of vector stochastic integrals (see Galtchouk, Proc. School-Seminar Vilnius, 1975, and Jacod 1419). \par Some topological considerations (that can be skipped if the reader is not interested in convergences of processes) are delicate to follow, specially since the theory of unbounded vector measures (in non-locally convex spaces!) requires much care and is difficult to locate in the literature
Keywords: Semimartingales, Formal semimartingales, Stochastic integrals
Nature: Original
Retrieve article from Numdam
XV: 33, 499-522, LNM 850 (1981)
STRICKER, Christophe
Quelques remarques sur la topologie des semimartingales. Applications aux intégrales stochastiques (Stochastic calculus)
This paper contains a number of useful technical results on the topology of semimartingales (see 1324), some of which were previously known with more complicated proofs. In particular, it is shown how to improve the convergence of sequences of semimartingales by a convenient change of probability. The topology of semimartingales is used to handle elegantly the stochastic integration of previsible processes which are not locally bounded (see 1415). Finally, boundedness of a set of semimartingales is shown to be equivalent to the boundedness (in an elementary sense) of a set of increasing processes controlling them in the sense of Métivier-Pellaumail (see 1412, 1413, 1414)
Keywords: Semimartingales, Stochastic integrals, Spaces of semimartingales, Métivier-Pellaumail inequality
Nature: Original
Retrieve article from Numdam
XVI: 27, 314-318, LNM 920 (1982)
LENGLART, Érik
Sur le théorème de la convergence dominée (General theory of processes, Stochastic calculus)
Consider previsible processes $U^n,U$ such that $U^n_T\rightarrow U_T$ in some sense at bounded previsible times $T$. The problem discussed is whether stochastic integrals $\int U^n_s dX_s$ converge (in the same sense) to $\int U_sdX_s$. Under a domination hypothesis, the answer is shown to be positive if the convergence is either weak convergence in $L^1$, or convergence in probability. The existence of the limiting process $U$ is not assumed in the paper; it is proved by a modification of an argument of Mokobodzki for which see 1110
Keywords: Stopping times, Optional processes, Weak convergence, Stochastic integrals
Nature: Original
Retrieve article from Numdam
XX: 02, 28-29, LNM 1204 (1986)
FAGNOLA, Franco; LETTA, Giorgio
Sur la représentation intégrale des martingales du processus de Poisson (Stochastic calculus, Point processes)
Dellacherie gave in 805 a proof by stochastic calculus of the previsible representation property for the Wiener and Poisson processes. A gap in this proof is filled in 928 for Brownian motion and here for Poisson processes
Keywords: Stochastic integrals, Previsible representation, Poisson processes
Nature: Correction
Retrieve article from Numdam
XXVI: 18, 189-209, LNM 1526 (1992)
NORRIS, James R.
A complete differential formalism for stochastic calculus in manifolds (Stochastic differential geometry)
The use of equivariant coordinates in stochastic differential geometry is replaced here by an equivalent, but intrinsic, formalism, where the differential of a semimartingale lives in the tangent bundle. Simple, intrinsic Girsanov and Feynman-Kac formulas are given, as well as a nice construction of a Brownian motion in a manifold admitting a Riemannian submersion with totally geodesic fibres
Keywords: Semimartingales in manifolds, Stochastic integrals, Feynman-Kac formula, Changes of measure, Heat semigroup
Nature: Original
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XLIII: 07, 191-214, LNM 2006 (2011)
RIEDLE, Markus
Cylindrical Wiener Processes
Keywords: Cylindrical Wiener process, Cylindrical process, Cylindrical measure, Stochastic integrals, Stochastic differential equations, Radonifying operator, Reproducing kernel Hilbert space
Nature: Original
XLIII: 12, 309-325, LNM 2006 (2011)
TUDOR, Ciprian A.
Asymptotic Cramér's theorem and analysis on Wiener space (Limit theorems, Stochastic analysis)
Keywords: Multiple stochastic integrals, Limit theorems, Malliavin calculus, Stein's method
Nature: Original
XLIII: 18, 413-436, LNM 2006 (2011)
CZICHOWSKY, Christoph; SCHWEIZER, Martin
Closedness in the semimartingale topology for spaces of stochastic integrals with constrained integrands
Keywords: Stochastic integrals, Constrained strategies, Semimartingale topology, Closedness, Predictably convex, Projection on predictable range, Predictable correspondence, Optimisation under constraints, Mathematical finance
Nature: Original
XLV: 13, 323-351, LNM 2078 (2013)
BOURGUIN, Solesne; TUDOR, Ciprian A.
Malliavin Calculus and Self Normalized Sums (Theory of processes)
Keywords: Malliavin calculus, Stein's method, self-normalized sums, limit theorems, multiple stochastic integrals, chaos expansions
Nature: Original