This paper concerns a class of stochastic differential equations driven by fractional Brownian motion. The existence and uniqueness of almost automorphic solutions in distribution are established provided the coefficients satisfy some suitable conditions. To illustrate the results obtained in the paper, a stochastic heat equation driven by fractional Brownian motion is considered. 1
K E Y W O R D Salmost automorphic solutions, fractional Brownian motion, stochastic differential equations M S C ( 2 0 1 0 ) 34C27, 60E05, 60H10, 93C30
INTRODUCTIONIt is well known that the recurrence of stochastic processes introduced by Kolmogorov in 1930's [24] is similar to the recurrence of dynamical systems introduced by Birkhoff in 1910's [5]. In dynamical systems, the almost automorphy is a class of basic recurrence introduced by Bochner [6], which is a generalization of almost periodicity [7]. Almost automorphy functions and almost automorphic solutions for differential systems have been studied by many authors; see Veech [34], N'Gu'er'ekata [17], Johnson [22], N'Gu'er'ekata [18], Ding, Liang and Xiao [11][12][13], Shen and Yi [31] and N'Gu'er'ekata [19], for more details about these topics and recent developments. Accordingly, the concept of distributionally almost automorphy for stochastic processes was introduced in [14,15].Many authors investigated almost periodic or pseudo almost periodic solutions for stochastic differential equations; see literature, for example, [1,3,8,20,32]. Mellah and De Fitte [28] gave some counterexamples to mean square almost periodicity of solutions for some stochastic differential equations with almost periodic coefficients. Hence it is a unique way to study some stochastic periodicity in distribution for stochastic differential equations. Almost periodic solutions in distribution and fundamental averaging results for stochastic differential equations were studied in [23]. Almost automorphic stochastic processes and their generalizations have been investigated only since 2010 starting with [16]. There are some papers investigating almost automorphy in distribution [14,15,27]. In these paper, almost automorphic solutions in distribution of stochastic differential equations driven by Gaussian processes or non-Gaussian processes were studied. In [2], the history of almost automorphic stochastic processes and their generalizations were given, and the existence and uniqueness of pseudo almost automorphic mild solutions for stochastic differential equations were also obtained.Recently, the definition and some properties of almost automorphic random functions in probability has been introduced by Ding, Deng and N'Guérékata [10]. Mathematische Nachrichten. 2019;292:983-995.