Strong Borel-Cantelli laws and clusters of visits for random intermittent maps

Abstract

Near the neutral fixed point of an intermittent map, a single entrance into a small target can be followed by a long run of consecutive visits, so the number of visits need not follow its mean. We study targets $[0,u_n]$ for iid random compositions of Liverani-Saussol-Vaienti maps with a bounded parameter law that is regularly varying at its minimum $α\in(0,1)$; this includes a single map. For $u_n=cn^{-g}L(n)$, where $c>0$, $0<g\leq1$ and $L$ is slowly varying, the visit count is almost surely asymptotic to its mean if and only if $\sum_n n^{-1}(nu_n)^{-(1-α)/α}<\infty$. Under the stationary law, the count divided by its mean converges to one in $L^1$ exactly when $nu_n\to\infty$. Thus clusters of visits separate these two modes of convergence.