Modelling and Verifying Coalitions using Argumentation and ATL

During the last decade argumentation has evolved as a successful approach to formalize commonsense reasoning and decision making in multiagent systems. In particular, recent research has shown that argumentation can be used to provide a suitable framework for reasoning about coalition formation: which coalitions can be formed using different argumentation semantics. At the same time Alternating-time Temporal Logic (ATL for short) has been successfully used to reason about the behavior and abilities of coalitions of agents. However, an important limitation of ATL operators is that they account only for the existence of successful strategies of coalitions, not considering whether coalitions can be actually formed. This paper is an attempt to combine both frameworks in order to develop a logical system through which we can reason at the same time (1) about abilities of coalitions of agents and (2) about the formation of coalitions. In order to achieve this, we provide a formal extension of ATL, called Coalitional ATL (CoalATL for short), in which the actual computation of the coalition is modelled in terms of argumentation semantics. Moreover, we integrate goals as agents’ incentive to join coalitions and examine the model checking complexity. Particularly, we show that model checking CoalATL is ∆2 -complete in the most natural cases.