Logical Dynamics of Social Interaction
@ ESSLLI 2019
(last modified: )

Day 1
Day 2
Day 3
Day 4
Day 5


It is well-known that our social environment has an effect on us, our opinions and our information about the world. Indeed, our traits, features, preferences, beliefs and knowledge are transformed by the presence of others, with communication and social influence being two crucial ways our social contacts affect us. These phenomena are relevant not only for empirical sciences (e.g., social psychology) but also for theoretical ones (e.g., computer science).

This course, which will take place at ESSLLI 2019, discusses the fundamental ideas behind logical approaches for studying and reasoning about the way agents are affected by their social environment. Its main subject is recent proposals for modelling diverse forms of social influence, and its aim is to provide the participants with their key concepts, making emphasis not only on the underlying ideas but also on the main properties of their formal frameworks.

A more detailed description of the course's contents (including a motivation as well a list of references and the expected level of the participants) can be found here. The (current version [] of the) slides for each one of the lectures ara available below, and also as a single file here. For questions and comments, just send me an email to .


Day 1: explicit communication

The lecture provides a description of the basic acts of explicit communication among agents, public observations and agents’ communication, in order to familiarise the audience with the structures and techniques that will be used through the lectures.


Day 2: peer pressure

The lecture reviews an approach for representing peer pressure on the relative preference between two formulas. In this (multi-dimensional) modal setting, peer-pressure is represented as an operation that looks at whether the group has a strong/weak preference for one formula over the other, then changing individual preferences accordingly.


Day 3: threshold influence

The lecture focusses on an approach that models how a behaviour/trait is propagates through a network. Its basic model consists of agents, their features and their social relations; then, operations are defined in order to represent the way a given behaviour spreads. The operations are first given in terms of the agents’ behaviours, and then in terms of their knowledge about their behaviour.


Day 4: priority-based social influence

The lecture studies approaches in which there is a ranking among the agents, and thus some agents are more influential than others. Then it explores the case in which agents share their full beliefs/preferences, discussing also some variations.

  • Slides.
  • Further references:
    • Texts one and two on reliability-based preference change.


Day 5: creating social networks

The lecture examines the logical structure behind the creation of social groups, focussing on the threshold and the group-size approaches, as well as in some of their variations.

  • Slides.
  • Further references:
    • Texts one and two on social network creation (see also the overview here).