Abstract
The specification of interaction and of the related forms of reasoning is crucial in the research area of multi-agent systems and in many application areas. This article summarizes the activities and the achievements obtained by the authors in the last years. Two are the main research lines, respectively leading to the proposal of a mentalistic approach to the specification of agent interaction policies, based on the class of grammar logics, and the proposal of a constraint-based representation of regulative and declarative patterns of interaction inside commitment-based protocols.