Title：Logics for Strategic Reasoning of Socially Interacting Rational Agents

Speaker：Valentin Goranko (Department of Philosophy, Stockholm University)

Time: 2024/04/26 15:00-18:00

Location: Room 109, Lee Shau Kee Humanities Buildings No.3（李兆基人文学苑3号楼）, Peking University

Abstract：

　　Reasoning about socially interacting rational agents is about strategic abilities of individuals (agents) and groups (coalitions) of individuals to guarantee the achievement of their desired objectives, 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, introduced the early 2000s.

　　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.

　　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 this talk I will first present briefly Coalition Logic and then will introduce and discuss some more expressive and versatile logical systems, including some of these:

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. (time permitting) 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.

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