Rigidity times for weakly mixing dynamical system which are not rigidity times for any irrational rotation
arXiv:1406.7518
Abstract
We construct an increasing sequence of natural numbers with the property that is dense in $\T$ for any $þ\in \R\setminus \Q$, and a continuous measure on the circle such that $\lim_{n\to +\infty}\int_{\T}\|m_nθ\|dμ(θ)=0$. Moreover, for every fixed , the set is infinite. This is a sufficient condition for the existence of a rigid, weakly mixing dynamical system whose rigidity time is not a rigidity time for any system with a discrete part in its spectrum.