This work was supported by the National Natural Science Foundation of China (Grant Nos. 10171101, 79970120) ; a grant from Tsinghua University.
This paper extends exit theorems of Da Prato and Zabczyk to nonconstant diffusion coefficients.It uses extensively general, exponential estimates due to Peszat.
Supported by the National Natural Science Foundationof China(No.79970 12 0 )
Two typical ARCH models: the ASDARCH model and the APARCH model are analyzed. Let Y k and σ 2 k denote the log returns and the volatility. When the time interval h goes to zero, (Y k,σ 2 k), as a dis...