Host–Kra theory for -systems and multiple recurrence
Host–Kra theory for -systems and multiple recurrence
Abstract Let $\mathcal {P}$ be an (unbounded) countable multiset of primes (that is, every prime may appear multiple times) and let $G=\bigoplus _{p\in \mathcal {P}}\mathbb {F}_p$ . We develop a Host–Kra structure theory for the universal characteristic factors of an ergodic G -system. More specifically, we generalize the main results …