Persistence of iterated partial sums
Let denote the iterated partial sums. That is, , where . Assuming are integrable, zero-mean, i.i.d. random variables, we show that the persistence probabilities with (and whenever is symmetric). The converse inequality holds whenever the non-zero is bounded or when it has only finite third moment and in addition is squared integrable. Furthermore, for any non-degenerate squared integrable, i.i.d., zero-mean . In contrast, we show that for any there exist integrable, zero-mean...