Upper law of the iterated logarithm (source code)

= Upper law of the iterated logarithm
{title2=$\limsup_n\frac{S_n}{\sqrt{2n\log\log n}}\le1$}

For a <simple symmetric random walk>, geometric blocking and the <Borel-Cantelli first lemma> yield the upper estimate $\limsup_n S_n/\sqrt{2n\log\log n}\le1$ <almost surely>. Equality requires a separate lower-bound argument.