Michele Boreale1, Rocco De Nicola2, Rosario
1 Dipartimento di Scienze dell'Informazione, Universita' di Roma ``La Sapienza''
2 Dipartimento di Sistemi e Informatica, Universita' di Firenze
We study may and must testing-based preorders in an asynchronous setting. In particular, we provide some full abstraction theorems that offer alternative characterizations of these preorders in terms of context closure w.r.t. basic observables and in terms of traces and acceptance sets. These characterizations throw light on the asymmetry between input and output actions in asynchronous interactions and on the difference between synchrony and asynchrony.