Nous établissons des vitesses fines de convergence presque sûre pour les approximations des chemins rugueux Gaussiens, sous l’hypothèse que la fonction de covariance du processus Gaussien sous-jacent ait une -variation finie, . Dans le cas du mouvement Brownien, respectivement du Brownien fractionnaire (fBM), pour lesquels resp. , ce résultat généralise les résultats respectifs de (Trans. Amer. Math. Soc. 361 (2009) 2689-2718) et (Ann. Inst. Henri Poincasé Probab. Stat. 48 (2012) 518-550). Notamment, nous établissons le taux de convergence presque sure , tout , pour les approximations de Wong-Zakai et de type Milstein avec pas de discrétisation . Dans le cas du fBM, ce résultat résout une conjecture posée par les références ci-dessus.
Under the key assumption of finite -variation, , of the covariance of the underlying Gaussian process, sharp a.s. convergence rates for approximations of Gaussian rough paths are established. When applied to Brownian resp. fractional Brownian motion (fBM), resp. , we recover and extend the respective results of (Trans. Amer. Math. Soc. 361 (2009) 2689-2718) and (Ann. Inst. Henri Poincasé Probab. Stat. 48 (2012) 518-550). In particular, we establish an a.s. rate , any , for Wong-Zakai and Milstein-type approximations with mesh-size . When applied to fBM this answers a conjecture in the afore-mentioned references.
@article{AIHPB_2014__50_1_154_0, author = {Friz, Peter and Riedel, Sebastian}, title = {Convergence rates for the full gaussian rough paths}, journal = {Annales de l'I.H.P. Probabilit\'es et statistiques}, volume = {50}, year = {2014}, pages = {154-194}, doi = {10.1214/12-AIHP507}, mrnumber = {3161527}, zbl = {1295.60045}, language = {en}, url = {http://dml.mathdoc.fr/item/AIHPB_2014__50_1_154_0} }
Friz, Peter; Riedel, Sebastian. Convergence rates for the full gaussian rough paths. Annales de l'I.H.P. Probabilités et statistiques, Tome 50 (2014) pp. 154-194. doi : 10.1214/12-AIHP507. http://gdmltest.u-ga.fr/item/AIHPB_2014__50_1_154_0/
[1] Densities for rough differential equations under Hoermander's condition. Ann. of Math. (2) 171 (2010) 2115-2141. | MR 2680405 | Zbl 1205.60105
and .[2] Stochastic analysis, rough path analysis and fractional Brownian motions. Probab. Theory Related Fields 122 (2002) 108-140. | MR 1883719 | Zbl 1047.60029
and .[3] Differential equations driven by rough paths: an approach via discrete approximation. Appl. Math. Res. Express. AMRX (2007) Art. ID abm009, 40. | MR 2387018 | Zbl 1163.34005
.[4] A Milstein-type scheme without Lévy area terms for SDEs driven by fractional Brownian motion. Ann. Inst. Henri Poincaré Probab. Stat. 48 (2012) 518-550. | Numdam | MR 2954265 | Zbl 1260.60135
, and .[5] Convergence rates for the full Brownian rough paths with applications to limit theorems for stochastic flows. Bull. Sci. Math. 135 (2011) 613-628. | MR 2838093 | Zbl 1237.60044
and .[6] Differential equations driven by Gaussian signals. Ann. Inst. Henri Poincaré Probab. Stat. 46 (2010) 369-413. | Numdam | MR 2667703 | Zbl 1202.60058
and .[7] Multidimensional Stochastic Processes as Rough Paths. Cambridge Univ. Press, Cambridge, 2010. | MR 2604669 | Zbl 1193.60053
and .[8] A note on higher dimensional -variation. Electron. J. Probab. 16 (2011) 1880-1899. | MR 2842090 | Zbl 1244.60066
and .[9] Rate of convergence of Wong-Zakai approximations for stochastic partial differential equations. Appl. Math. Optim. 54 (2006) 315-341. | MR 2268661 | Zbl 1106.60050
and .[10] Rough stochastic PDEs. Comm. Pure Appl. Math. 64 (2011) 1547-1585. | MR 2832168 | Zbl 1229.60079
.[11] Fractional order Taylor's series and the neo-classical inequality. Bull. Lond. Math. Soc. 42 (2010) 467-477. | MR 2651942 | Zbl 1194.26027
and .[12] Rough path analysis via fractional calculus. Trans. Amer. Math. Soc. 361 (2009) 2689-2718. | MR 2471936 | Zbl 1175.60061
and .[13] Gaussian Hilbert Spaces. Cambridge Univ. Press, New York, 1997. | MR 1474726 | Zbl 1143.60005
.[14] Differential equations driven by rough signals. Rev. Mat. Iberoam. 14 (1998) 215-310. | MR 1654527 | Zbl 0923.34056
.[15] System Control and Rough Paths. Oxford Univ. Press, New York, 2002. | MR 2036784 | Zbl 1029.93001
and .[16] Discretizing the fractional Lévy area. Stochastic Process. Appl. 120 (2010) 223-254. | MR 2576888 | Zbl 1185.60076
, and .[17] Free Lie Algebras. Clarendon Press, New York, 1993. | MR 1231799 | Zbl 0798.17001
.[18] Multidimensional extension of L. C. Young's inequality. JIPAM J. Inequal. Pure Appl. Math. 3 (2002) 13 (electronic). | MR 1906391 | Zbl 0997.26007
.