Learning to infer structures of network games

Strategic interactions between a group of individuals or organisations can be modelled as games played on networks, where a player’s payoff depends not only on their actions but also on those of their neighbours. Inferring the network structure from observed game outcomes (equilibrium actions) is an important problem with numerous potential applications in economics and social sciences. Existing methods mostly require the knowledge of the utility function associated with the game, which is often unrealistic to obtain in real-world scenarios. We adopt a transformer-like architecture which correctly accounts for the symmetries of the problem and learns a mapping from the equilibrium actions to the network structure of the game without explicit knowledge of the utility function. We test our method on three different types of network games using both synthetic and real-world data, and demonstrate its effectiveness in network structure inference and superior performance over existing methods

Democratic Deliberation and Social Choice: A Review

In normative political theory, it is widely accepted that democracy cannot be reduced to voting alone, but that it requires deliberation. In formal social choice theory, by contrast, the study of democracy has focused primarily on the aggregation of individual opinions into collective decisions, typically through voting. While the literature on deliberation has an optimistic flavour, the literature on social choice is more mixed. It is centred around several paradoxes and impossibility results identifying conflicts between different intuitively plausible desiderata. In recent years, there has been a growing dialogue between the two literatures. This paper discusses the connections between them. Important insights are that (i) deliberation can complement aggregation and open up an escape route from some of its negative results; and (ii) the formal models of social choice theory can shed light on some aspects of deliberation, such as the nature of deliberation-induced opinion change

The advertising-financed business model in two-sided media markets

This chapter focuses on the economic mechanisms at work in recent models of advertising finance in media markets developed around the concept of two-sided markets. The objective is to highlight new and original insights from this approach, and to clarify the conceptual aspects. The chapter first develops a canonical model of two-sided markets for advertising, where platforms deliver content to consumers and resell their "attention" to advertisers. A key distinction is drawn between free media and pay media, where the former result from the combination of valuable consumer attention and low ad nuisance cost. The first part discusses various conceptual issues such as equilibrium concepts and the nature of inefficiencies in advertising markets, and concrete issues such as congestion and second-degree discrimination. The second part is devoted to recent contributions on issues arising when consumers patronize multiple platforms. In this case, platforms can only charge incremental values to advertisers which reduces their market power and affects their price strategies and advertising levels. The last part discusses the implications of the two-sided nature of the media markets for the choice of content and diversity

Essays on Games of Strategic Substitutes with Incomplete Information

This dissertation consists of three individual chapters. The first chapter applies lattice theoretic techniques in order to establish fundamental properties of Bayesian games of strategic substitutes (GSS) when the underlying type space is ordered either in increasing or decreasing first-order stochastic dominance. Existence and uniqueness of equilibria is considered, as well as the question of when such equilibria can be guaranteed to be monotone in type, a property which is used to guarantee monotone comparative statics. The second chapter uses the techniques of the first and combines them with the existing results for strategic complements (GSC) in order to extend the literature on global games under both GSC and GSS. In particular, the model of Carlsson and Van Damme (1993) is extended from 22 games to GSS or GSC involving a finite amount of players, each having a finite action space. Furthermore, the possibility that groups of players receive the same signal is allowed for, a condition which is new to the literature. It is shown that under this condition, the power of the model to resolve the issue of multiplicity is unambiguously increased. The third chapter considers stability of mixed strategy Nash equilibria in GSS. Chapter 1 analyzes Bayesian games of strategic substitutes under general conditions. In particular, when beliefs are order either increasingly or decreasingly by first order stochastic dominance, the existence and uniqueness, monotonicity, and comparative statics in this broad class of games are addressed. Unlike their supermodular counterpart, where the effect of an increase in type augments the strategic effect between own strategy and opponent’s strategy, submodularity produces competing effects when considering optimal responses. Using adaptive dynamics, conditions are given under which such games can be guaranteed to exhibit Bayesian Nash equilibria, and it is shown that in many applications these equilibria will be a profile of monotone strategies. Comparative statics of parametrized games is also analyzed using results from submodular games which are extended to incorporate incomplete information. Several examples are provided. The framework of Chapter 1 is applied to global games in Chapter 2. Global games methods are aimed at resolving issues of multiplicity of equilibria and coordination failure that arise in game theoretic models by relaxing common knowledge assumptions about an underlying parameter. These methods have recently received a lot of attention when the underlying complete information game is a GSC. Little has been done in this direction concerning GSS, however. This chapter complements the existing literature in both cases by extending the global games method developed by Carlsson and Van Damme (1993) to multiple player, multiple action GSS and GSC, using a p-dominance condition as the selection criterion. This approach helps circumvent recent criticisms to global games by relaxing some possibly unnatural assumptions on payoffs and parameters necessary to conduct analysis under current methods. The second part of this chapter generalizes the model by allowing groups of players to receive homogenous signals, which, under certain conditions, strengthens the model’s power of predictability. Chapter 3 analyzes the learning and stability of mixed strategy Nash equilibria in GSS, complementing recent work done in the case of GSC. Mixed strategies in GSS are of particular interest because it is well known that such games need not exhibit pure strategy Nash equilibria. First, a bound on the strategy space which indicate where randomizing behavior may occur in equilibrium is established. Second, it is shows that mixed strategy Nash equilibria are generally unstable under a wide variety of learning rules

Debating deliberative democracy: how deliberation changes the way people reason

The concepts of deliberation and deliberative democracy have attracted much attention in political theory over the past twenty years. At first seen as both highly idealised and unreflective of reality, they have now shed this accusation of impracticality, as practitioners and policy makers alike have attempted to institute deliberative principles on a national and international scale. Running alongside this has been the desire to both understand political deliberation and its effects more fully, and to then apply this new information back to deliberative democratic theory. This thesis sits in the latter tradition, presenting an empirical investigation of political deliberation and then discussing how it relates back to deliberative models of democracy. Where it departs from all of the contemporary experimental work, however, is the methodology and conceptual model it is founded upon. Embracing the decision and game theoretic approaches, I develop a three-fold framework to study the effects of deliberation on individual decision-making. After outlining two levels of ‘preference’ and ‘issue’, I focus on the third, which I term agency. I then compare a particular case of agency revision, which moves people from individualistic to team reasoning, before developing and putting into action an experimental test of the phenomenon. Finally, I then combine these results with the most recent drive in deliberative democracy towards a systemic approach, and derive an alternative, more positive argument for this recasting

Social Media Networks: The Social Influence of Sentiment Content in Online Conversations on Dynamic Patterns of Adoption and Diffusion

The current study is focusing on diffusion and adoption of new digital artifacts. The goal is to explore the social role of user-generated content (UGC) during the diffusion process of digital artifacts in the context of online social networks. The study spans a wide range of analytics methods and tools such as predictive modeling, latent sentiment analysis, data retrieval, and other tools of time-series analysis & visualization. Data collection is conducted on 260 new digital products and more than 105 thousand social network nodes. Results of the study provide a deeper insight into the influence of textual UGC sentiment on new product diffusion and how such a web system (i.e.: online social networks) can help to enable a process of value co-creation. The overall finding shows that Volume of Post and UGC Sentiment have a dynamic impact on Diffusion (Adoption Rate) of digital products. But, the relationships among them depend on certain situations. Specifically, UGC Sentiment has a dynamic impact on Adoption Rate in the early stage of the diffusion process. That is UGC Sentiment and Adoption Rate have a reciprocal relationship during the early stage. However, this relationship was faded out in the later stage. Volume of Post has a positive impact on Adoption Rate throughout the process. Both UGC Sentiment and Volume of Post are also more likely to influence on a single-generation and successful product than a multiple-generation product. Surprisingly, Depth of Post and Ratings did not play a significant role in the diffusion process. The study sheds light on the crowding power and the long-tail effect in online social networks. Findings also offer valuable implications for organizations to set up their strategic vision in terms of targeted marketing, customer relationship management, and information dissemination

EUSN 2021 Book of Abstracts, Fifth European Conference on Social Networks

Book of abstract of the fifth European conference on Social Networks EUSN 202