On the abstract elementary class of acts with embeddings

We study the class of acts with embeddings as an abstract elementary class. We show that the class is always stable and show that superstability in the class is characterized algebraically via weakly noetherian monoids. The study of these model-theoretic notions and limit models lead us to introduce parametized weakly noetherian monoids and find a characterization of them via parametrized injective acts. Furthermore, we obtain a characterization of weakly noetherian monoids via absolutely pure acts extending a classical result of ring theory. The paper is aimed at algebraists and model theorists so an effort was made to provide the background for both.