Additive realizations of asymptotically additive set maps

Abstract: Given a countable discrete amenable group, we investigate the conditions under which a set map into a Banach space (or more generally, a complete semi-normed space) can be realized as the ergodic sum of a vector under a group representation, such that the realization is asymptotically indistinguishable from the original map. We show that for uniformly bounded group representations, this property is characterized by the class of bounded asymptotically additive set maps, extending previous work for sequences in Banach spaces and single contractions. Additionally, we develop a relative version of this characterization, identifying conditions under which the additive realization can be chosen within a specified target set. As an application, our results generalize key aspects of thermodynamic formalism, bridging the gap between additive and non-additive frameworks.