14.30 Prof Mario Gilli (Università Milano Bicocca)
“Equilibria and Stability in a Model of Political and Social Conflict. The Symmetric Case”
Conflicts are ubiquitous in social and political environments. Two are the common characteristics of these, otherwise extremely different, conflicts: very often they came as a surprise and their evolution through time is usually very heterogenous, sometimes they quickly disappear sometimes they degenerate in catastrophe. If we consider World War I, one hundred years later, historians still wonder how such a catastrophic war came almost out of nowhere and why what could have been a manageable crisis turned into all-out-war. In the end, the historians’ conclusion is that there are no sure solutions, because contexts change: what will turn off conflicts in one setting will spread the conflict as if it is a wildfire. From a theoretical point of view, we believe that these phenomena can be explained in two different and complementary ways: either using comparative statics showing how equilibria properties change suddenly as parameters (contexts) change, or with multiple equilibria and out-of equilibrium dynamics to emphasize the complex and cyclic behavior of conflicts. In this paper, we study the result of symmetric strategic interaction between two parties. Both parties are able to mobilize a certain effort to pursue their goals, that are partially diverging. The target of their political action can be the government, as well as public policies or private objects, but they have all in common a conflict situation, which starts from a particular historical situation and which can evolve in several different ways, so that, depending on the results that are achieved during the evolutions, the starting situation and the actions of the involved actors, it can break up, it can stabilize at a particular level, it can grow up and become a mass movement or it can ebb and flow periodically. We present a model in which the efforts of both the opponents are described as the outcome of strategic decisions, and the evolution is governed by several factors. Hence, the initial conditions describing the historical premises of the political (or social, economical) situation can define the final outcome of the conflict, which eventually could be independent of the other aspects.
15.45 Dr. Michela Chessa (Eurecom, France)
“Personal Information on Social Networks: Incentives for Data Release and Fair Monetization”
Recent years have seen the explosion of online business models based on the exploitation of users’ personal data collected on social networks. The potential benefits of this ecosystem, however, are currently undermined by tussles around privacy and the uncontrolled use of this data. In this talk, we propose and analyze new game-theoretic models that allow us to discuss economics and incentives challenges arising in a personal data ecosystem where users have control over their data. In the first part of the talk, we present a user-centric public good model, in which users have full control of their personal information and strategically choose whether they want to reveal some data and with which precision. We analyze the users’ incentives to obfuscate their data and to reveal truthfully the precision of the data disclosed. We then propose simple ways in which an analyst collecting the data can increase the aggregate precision level by slightly modifying the game. In the second part of the talk, we focus on the economic value of personal data. In a social network, the value of data revealed depends on data revealed by other users. To analyze the impact of the social network on this value, we propose a cooperative game theoretic model on a graph. We then propose a fair mechanism based on the Shapley value to quantify the value of the personal information of each user depending on his social interactions, and we analyze the impact on the system of our mechanism.
17.00 Prof. Nicola Gatti (Politecnico di Milano)
"Efficient algorithms for the verification problem of sequential equilibrium and quasi-perfect equilibrium"
We study the computational problem (aka verification problem) of certifying that a given solution is a sequential equilibrium and/or a quasi-perfect equilibrium. While the verification problem of Nash equilibrium is easy, only results of NP–hardness are known for Nash equilibrium refinements for sequential games. We show that, when the assessment (i.e., a pair defining agents’ behavioral strategies and beliefs) is given in input, there exists an efficient algorithm with any number of agents. Furthermore, we show that, when only the behavioral strategy profile is given in input, there exists an efficient algorithm with two–agent games (with more agents the problem is already known to be NP–hard). The algorithm can be also adopted to derive the agents’ consistent (in the sense of Kreps and Wilson) beliefs from their strategies. In addition, a simple variation of this algorithm can be adopted for the verification problem of the quasi–perfect equilibrium in two–agent games (also in this case, with more agents the problem is already known to be NP–hard).
|Equilibria and Stability in a Model of Political and Social Conflict.|
|File Size:||755 kb|