杨新建
设$B(t)=(B(t))=(B_1(t),B_2(t), \cdots, B_N(t))$为$N$维Brown运动,设$\alpha(x)=(\alpha_{ij}(x),1\leqi\leq d, 1\leq j\leq N),\ \beta(x)=(\beta_i(x), 1\leq i\leq d), x\in R^d, 1\leq d\leq N$, $\alpha(x)$和$\beta(x)$有界连续和满足Lipchitz条件,且存在常数$c_0>0, $使得对每个$x\in R^d$, $a(x)=\alpha(x)\alpha(x)^*$的每个特征根都不小于$c_0$. 设${\rm d}X(t)=\alpha(X(t)){\rm d}B(t)+\beta(X(t)){\rm d}t$, 设$d\geq3$.
可以证明
$$P(\omega: {\rm Dim} X(E, \omega)= {\rm Dim} GRX(E, \omega)= 2{\rm Dim} E, \q \forall E\in{\mathcal{B}}[0,\infty))=1. $$这里 $X(E, \omega)=\{X(t, \omega):
t\in E\}, GRX(E, \omega)=\{(t, X(t, \omega)): t\in E\}, {\rm Dim}F$表示$F$的Packing维数.