On the functional CLT for slowly mixing triangular arrays

Abstract

In \cite{MPU} a functional CLT was obtained for triangular arrays satisfying the Lindeberg condition, that the sum of the individual variances is at most the same order as the variance of the underlying sum, and under the optimal mixing rats $\sum_{n}\rho(2^n)<\infty$, where $\rho(\cdot)$ are the $\rho$-mixing coefficients of the array. In this paper we will present alternative conditions which do not involve the assumption on the sum of variances, and instead we will assume certain maximal moment assumptions (which we can verify for $\phi$-mixing arrays) and mixing rates of the form $\sum_n\rho(e^{G(n)})<\infty$ where $G(n)$ grows sub-linearly fast in $n$ (e.g. $G(n)=n/\ln(\ln n)$). We will also discuss alternative conditions to the ones in the functional CLT for $\alpha$-mixing triangular arrays which was obtained in \cite{MP}.