Maximal brownian motions

Jean Brossard; Michel Émery; Christophe Leuridan

Annales de l'I.H.P. Probabilités et statistiques (2009)

  • Volume: 45, Issue: 3, page 876-886
  • ISSN: 0246-0203

Abstract

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Let Z=(X, Y) be a planar brownian motion, 𝒵 the filtration it generates, andBa linear brownian motion in the filtration 𝒵 . One says thatB(or its filtration) is maximal if no other linear 𝒵 -brownian motion has a filtration strictly bigger than that ofB. For instance, it is shown in [In Séminaire de Probabilités XLI 265–278 (2008) Springer] that B is maximal if there exists a linear brownian motion C independent of B and such that the planar brownian motion (B, C) generates the same filtration 𝒵 asZ. We do not know if this sufficient condition for maximality is also necessary. We give a necessary condition for B to be maximal, and a sufficient condition which may be weaker than the existence of such a C. This sufficient condition is used to prove that the linear brownian motion ∫(X dY−Y dX)/|Z|, which governs the angular part of Z, is maximal.

How to cite

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Brossard, Jean, Émery, Michel, and Leuridan, Christophe. "Maximal brownian motions." Annales de l'I.H.P. Probabilités et statistiques 45.3 (2009): 876-886. <http://eudml.org/doc/78049>.

@article{Brossard2009,
abstract = {Let Z=(X, Y) be a planar brownian motion, $\mathcal \{Z\}$ the filtration it generates, andBa linear brownian motion in the filtration $\mathcal \{Z\}$. One says thatB(or its filtration) is maximal if no other linear $\mathcal \{Z\}$-brownian motion has a filtration strictly bigger than that ofB. For instance, it is shown in [In Séminaire de Probabilités XLI 265–278 (2008) Springer] that B is maximal if there exists a linear brownian motion C independent of B and such that the planar brownian motion (B, C) generates the same filtration $\mathcal \{Z\}$ asZ. We do not know if this sufficient condition for maximality is also necessary. We give a necessary condition for B to be maximal, and a sufficient condition which may be weaker than the existence of such a C. This sufficient condition is used to prove that the linear brownian motion ∫(X dY−Y dX)/|Z|, which governs the angular part of Z, is maximal.},
author = {Brossard, Jean, Émery, Michel, Leuridan, Christophe},
journal = {Annales de l'I.H.P. Probabilités et statistiques},
keywords = {brownian filtration; maximal brownian motion; exchange property; Brownian filtration; maximal Brownian motion},
language = {eng},
number = {3},
pages = {876-886},
publisher = {Gauthier-Villars},
title = {Maximal brownian motions},
url = {http://eudml.org/doc/78049},
volume = {45},
year = {2009},
}

TY - JOUR
AU - Brossard, Jean
AU - Émery, Michel
AU - Leuridan, Christophe
TI - Maximal brownian motions
JO - Annales de l'I.H.P. Probabilités et statistiques
PY - 2009
PB - Gauthier-Villars
VL - 45
IS - 3
SP - 876
EP - 886
AB - Let Z=(X, Y) be a planar brownian motion, $\mathcal {Z}$ the filtration it generates, andBa linear brownian motion in the filtration $\mathcal {Z}$. One says thatB(or its filtration) is maximal if no other linear $\mathcal {Z}$-brownian motion has a filtration strictly bigger than that ofB. For instance, it is shown in [In Séminaire de Probabilités XLI 265–278 (2008) Springer] that B is maximal if there exists a linear brownian motion C independent of B and such that the planar brownian motion (B, C) generates the same filtration $\mathcal {Z}$ asZ. We do not know if this sufficient condition for maximality is also necessary. We give a necessary condition for B to be maximal, and a sufficient condition which may be weaker than the existence of such a C. This sufficient condition is used to prove that the linear brownian motion ∫(X dY−Y dX)/|Z|, which governs the angular part of Z, is maximal.
LA - eng
KW - brownian filtration; maximal brownian motion; exchange property; Brownian filtration; maximal Brownian motion
UR - http://eudml.org/doc/78049
ER -

References

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  1. [1] S. Attal, K. Burdzy, M. Émery and Y. Hu. Sur quelques filtrations et transformations browniennes. In Séminaire de Probabilités XXIX 56–69. Lecture Notes in Mathematics 1613. Springer, Berlin, 1995. Zbl0835.60073MR1459449
  2. [2] J. Brossard and C. Leuridan. Filtrations browniennes et compléments indépendants. In Séminaire de Probabilités XLI 265–278. Lecture Notes in Mathematics 1934. Springer, 2008. Zbl1149.60319MR2483736
  3. [3] M. Émery. On certain almost Brownian filtrations. Ann. Inst. H. Poincaré Probab. Statist. 41 (2005) 285–305. Zbl1082.60070MR2139021
  4. [4] D.W. Stroock and M. Yor. Some remarkable martingales. In Séminaire de Probabilités XV 590–603. Lecture Notes in Mathematics 850. Springer, Berlin, 1980. Zbl0456.60048MR622590
  5. [5] H. von Weizsäcker. Exchanging the order of taking suprema and countable intersections of σ-algebras. Ann. Inst. H. Poincaré Probab. Statist. 19 (1983) 91–100. Zbl0509.60002MR699981

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