This tutorial will give an introduction to logic-based reasoning of, and about, the individual and coalitional abilities of rational agents to ensure the achievement of their individual and collective goals while acting and interacting within an entire society of agents.

Several logical systems have been proposed for formalising and capturing such reasoning, starting with the Coalition Logic (CL), the Alternating Time Temporal Logic (ATL), and some extensions of these since the early 2000s.

In the lecture 1 of this tutorial I will briefly present and illustrate the use of these logics, under various assumptions for the observability and memory capacities of the agents. Coalition Logic provides a natural, but rather restricted perspective: the agents in the proponent coalition are viewed as acting in full cooperation with each other but in complete opposition to all agents outside of the coalition, which are thus treated as adversaries. The Alternating Time Temporal Logic extends Coalition Logic with temporal operators allowing for expressing long-term temporised goals. Thus, both logics are only suited for reasoning about unconditional strategic abilities of agents and coalitions.

The strategic interaction in real life is much more complex, usually involving various patterns combining cooperation and competition. To capture these, more expressive and versatile logical frameworks are needed. In lectures 2 and 3 of the tutorial I will introduce and discuss some more expressive and versatile logical systems, including:  

i. the Socially Friendly Coalition Logic (SFCL), enabling formal reasoning about strategic abilities of individuals and groups to ensure achievement of their private goals while allowing for cooperation with the entire society;  

ii. the Logic of Coalitional Goal Assignments (LCGA), capturing reasoning about strategic abilities of the entire society to cooperate in order to ensure achievement of the societal goals, while simultaneously protecting the abilities of individuals and groups within the society to achieve their individual and group goals.

iii. the Logic for Conditional Strategic Reasoning ConStR, formalising reasoning about agents’ strategic abilities conditional on the actions that they expect the other agents to take.

iv. In conclusion, I will take a more general perspective on a unifying logic-based framework for strategic reasoning in social context, called Basic Strategy Logic.  

The tutorial will assume basic background in classical logic. Some background in modal and temporal logic, too, would be an advantage.  


Key references:

1.M. Pauly: A Modal Logic for Coalitional Power in Games, Journal of Logic and Computation, Vol. 12(1), 2002, pp. 149–166. Available from https://academic.oup.com/logcom/article-pdf/12/1/149/3657514/120149.pdf 
2.R. Alur, T.A. Henzinger, and O. Kupferman: Alternating-time temporal logic. Journal of the ACM 49:672–713, 2002. (only pages 1-19). Available from https://www.cis.upenn.edu/~alur/Jacm02.pdf 
3.W. van der Hoek and M.J.W. Wooldridge: Cooperation, Knowledge, and Time: Alternating-time Temporal Epistemic Logic and its Applications, Studia Logica,75:1, pp. 125–157, 2003. Available from https://link.springer.com/content/pdf/10.1023/A:1026185103185.pdf 
4.V. Goranko and S. Enqvist: Socially Friendly and Group Protecting Coalition Logics, Proc. of AAMAS'2018, IFAAMAS publ., 2018, pp 372–380.
Available from http://ifaamas.org/Proceedings/aamas2018/pdfs/p372.pdf 
5.V. Goranko and F. Ju: A Logic for Conditional Local Strategic Reasoning, Journal of Logic, Language and Information, 2021, special issue of LORI VII, vol. 31, pp167–188, 2022.  Available from https://arxiv.org/abs/2102.06148.pdf    
6.S. Enqvist and V. Goranko: The temporal logic of coalitional goal assignments in concurrent multi-player games, ACM Transactions of Computational Logic, Vol. 23, No. 4, Article 21, 2022.  Available from https://arxiv.org/abs/2012.14195    
7.V. Goranko: Logics for Strategic Reasoning of Socially Interacting Rational Agents: An Overview and Perspectives, Logics, vol. 1(1), 2023.  Available from: https://www.mdpi.com/2813-0405/1/1/3