Formal threads in the social fabric Studies in the logical dynamics of multi-agent interaction

Interactions between people are a defining feature of social life. Our actions tend to be reactions to what others have done, while others again respond to our behavior. This never-ending entanglement can be observed across a wide range of settings including exchange of information, spread of opinions in social networks, cooperation and competition in economic or academic activities, and even social relationships themselves are in dynamic flux. While these phenomena have been studied in many disciplines, from sociology and economic game theory to social epistemology or philosophy of action, this dissertation pursues a logical perspective. Social interaction is a core topic in current logics of multi- agent systems at the interface of philosophy, computer science and AI, and the resulting systems have been applied to better understand human behavior, but also to design new forms of behavior by both human and artificial agents. This dissertation continues within this multi-agency tradition, especially, that of dynamic-epistemic logics, and explores two new logical perspectives that highlight two further basic properties of social interaction. The first topic is multi-agent interaction under adverse circumstances. This arises when agents are deeply at odds, to the extent that they try to change the very setting (physical or otherwise) where their interactions take place. Next, the second part is to study abstract general structures that play across many scenarios at the same time. Our particular interest here is the notion of dependence of behavior for agents engaged in social activities.