Infinite sumsets in $U^k(Φ)$-uniform sets

Abstract: Extending recent developments of Kra, Moreira, Richter and Roberson, we study infinite sumset patterns in $U^k(Φ)$-uniform subsets of the integers, defined via the local uniformity seminorms introduced by Host and Kra. The main result relates the degree $k$ of a $U^k(Φ)$-uniform set to the existence of sumset patterns along prescribed vertices of $\ell$-dimensional parallelepipeds, for $k \leq \ell$. The proof relies on a dynamical analysis of return-time sets to neighborhoods of points lying over pronilfactor fibers. We then derive higher-order parity obstructions for sumset patterns and consequences in topological dynamics.