Title: Norm-variation of double ergodic averages
Abstract: We study double ergodic averages with respect to two general commuting transformations and establish a quantitative result on their convergence in the norm. We approach the problem via real harmonic analysis, using methods for bounding multilinear singular integrals with certain entangled structure. This is joint work with Vjekoslav Kovač, Kristina Ana Škreb and Christoph Thiele.