Social Network Games with Obligatory Product Selection

Recently, Apt and Markakis introduced a model for product adoption in social networks with multiple products, where the agents, influenced by their neighbours, can adopt one out of several alternatives (products). To analyze these networks we introduce social network games in which product adoption is obligatory. We show that when the underlying graph is a simple cycle, there is a polynomial time algorithm allowing us to determine whether the game has a Nash equilibrium. In contrast, in the arbitrary case this problem is NP-complete. We also show that the problem of determining whether the game is weakly acyclic is co-NP hard. Using these games we analyze various types of paradoxes that can arise in the considered networks. One of them corresponds to the well-known Braess paradox in congestion games. In particular, we show that social networks exist with the property that by adding an additional product to a specific node, the choices of the nodes will unavoidably evolve in such a way that everybody is strictly worse off.Comment: In Proceedings GandALF 2013, arXiv:1307.416

Assortative Mixing Equilibria in Social Network Games

It is known that individuals in social networks tend to exhibit homophily (a.k.a. assortative mixing) in their social ties, which implies that they prefer bonding with others of their own kind. But what are the reasons for this phenomenon? Is it that such relations are more convenient and easier to maintain? Or are there also some more tangible benefits to be gained from this collective behaviour? The current work takes a game-theoretic perspective on this phenomenon, and studies the conditions under which different assortative mixing strategies lead to equilibrium in an evolving social network. We focus on a biased preferential attachment model where the strategy of each group (e.g., political or social minority) determines the level of bias of its members toward other group members and non-members. Our first result is that if the utility function that the group attempts to maximize is the degree centrality of the group, interpreted as the sum of degrees of the group members in the network, then the only strategy achieving Nash equilibrium is a perfect homophily, which implies that cooperation with other groups is harmful to this utility function. A second, and perhaps more surprising, result is that if a reward for inter-group cooperation is added to the utility function (e.g., externally enforced by an authority as a regulation), then there are only two possible equilibria, namely, perfect homophily or perfect heterophily, and it is possible to characterize their feasibility spaces. Interestingly, these results hold regardless of the minority-majority ratio in the population. We believe that these results, as well as the game-theoretic perspective presented herein, may contribute to a better understanding of the forces that shape the groups and communities of our society

Trust in Social Network Games

We consider agents in a social network competing to be selected as partners in collaborative, mutually beneficial activities. We study this through a model in which an agent i can initiate a limited number k_i>0 of games and selects the ideal partners from its one-hop neighborhood. On the flip side it can accept as many games offered from its neighbors. Each game signifies a productive joint economic activity, and players attempt to maximize their individual utilities. Unsurprisingly, more trustworthy agents are more desirable as partners. Trustworthiness is measured by the game theoretic concept of Limited-Trust, which quantifies the maximum cost an agent is willing to incur in order to improve the net utility of all agents. Agents learn about their neighbors' trustworthiness through interactions and their behaviors evolve in response. Empirical trials performed on realistic social networks show that when given the option, many agents become highly trustworthy; most or all become highly trustworthy when knowledge of their neighbors' trustworthiness is based on past interactions rather than known a priori. This trustworthiness is not the result of altruism, instead agents are intrinsically motivated to become trustworthy partners by competition. Two insights are presented: first, trustworthy behavior drives an increase in the utility of all agents, where maintaining a relatively modest level of trustworthiness may easily improve net utility by as much as 14.5%. If only one agent exhibits modest trust among self-centered ones, it can increase its average utility by up to 25% in certain cases! Second, and counter-intuitively, when partnership opportunities are abundant agents become less trustworthy.Comment: Main paper plus e-companio

Using social network games to reduce energy consumption

This research is investigating the potential role of online social network based life simulation computer games as a persuasive tool for encouraging users to reduce their domestic energy consumption. Games such as ‘Farmville’ which runs on the Facebook platform have attracted millions of users worldwide who create simple virtual worlds where they interact with others and carry out everyday activities to earn tokens to spend within the game. Applying a User Centred Design (UCD) and in particular persona based design approach, this research is investigating why users find these games so enticing, the characteristics of those who play them, and the context in which they are played. Through an iterative UCD process, a life simulation game will be designed with users who represent a number of key ‘gamer personas’ in order to research how this sort of game could be used to encourage domestic energy saving behaviours

What is the “value” of value-at-risk in a simulated portfolio decision-making game?

In the paper, I simulate the social network games of a portfolio selection where agents consider VaR when managing their portfolios. Such agents behave quite differently from the agents considering only the expected returns of the alternatives that are available to them in time. The level of omniscience of agents and the presence of liquidity agents are demonstrated to be significant factors for the portfolio management.social networks; portfolio decision-making; stochastic finance; Value-at-Risk

The Role of Liquidity Individuals in the Decision-Making

We simulate social network games of a portfolio selection to analyze the role of liquidity individuals for the developments in individuals’ decision-making in financial markets. Liquidity individuals prove to be a significant element in the decision-making process of the entire network, as they keep the information of non-dominant strategies alive. Their role is especially significant under omniscient individuals, whereas a little less under non-omniscient individuals. As long as individuals do not lose the information of all the alternatives, their role is insignificant.social networks, portfolio analysis, stochastic finance

Monetization of Social Network Games in Japan and the West

Social Network Games (SNGs) first appeared in Asia in the latter half of the 00s, and soon became a widespread phenomenon all over the world. In the West, US developer Zynga quickly rose to fame with their hit title FarmVille, and now enjoys a nearly monopolistic position among games on Facebook. In Japan as well, the SNG industry has grown at an exceptional pace since its birth and is predicted to keep growing. Most SNGs use a business model called free-to-play, which allows the player to play the game for free unless the player chooses to pay for some virtual item available in the game. This makes it important for games to monetize their users by providing players with incentives to pay a small fee to enhance their experience. It has long been known that SNGs in Japan are more profitable than Western ones when it comes to revenue per user. The accepted explanation for this has been that special characteristics of the Japanese market make it easier to monetize users on the Japanese market, as they are more willing to pay for games. However, as the Japanese SNG market is becoming saturated, several developers are going global, and 2012 saw a storm of Japanese SNGs being released in the US and other Western markets. Far from all of these games were successful, but some of them are performing very well. In particular, the card battle role playing game (RPG) Rage of Bahamut quickly reached the top position of highest grossing apps on both the iPhone App Store and the Android Google Play Store in the US. Moreover, the game’s publisher reports average revenue per daily active user (ARPDAU) which is twenty times higher than the US market average. Several other Japanese developers with titles released on the US market are reporting similar numbers, which has led to speculation that perhaps the success of Japanese SNGs is not only due to market differences. The purpose of this thesis is to further understand if and how Japanese SNGs monetize better than Western games. The study seeks answers to the following research questions: 1. How do the game mechanics differ between Japanese and Western SNGs? 2. What game mechanics affect how much a player is willing to pay? In order to do test this, twelve SNGs, six Japanese and six Western, are tested and analyzed using an analysis model. The analysis model is based on research on game design as well as on gamification; a field which is closely related to SNGs. Using the analysis model, game characteristics which could affect monetization are identified. In addition to the comparative game study, a market analysis is performed for both markets, in attempt to find information about the markets which cannot be easily obtained only by testing the games hands-on. The study found that Japanese and Western SNGs differ in several ways. For each market, five unique characteristics are identified and explained. Whether the five characteristics found for Japanese SNGs are directly related to the games’ monetization or not is difficult to tell without access to the games’ KPIs. However, information gained in the market analysis suggests that some of the identified characteristics are indeed what makes Japanese SNGs monetize better

Love thy Neighbor, Love thy Kin: Voting Biases in the Eurovision Song Contest

The Eurovision Song Contest provides a setting where Europeans can express their sentiments about other countries without regard to political sensitivities. Analyzing voting data from the 25 contests between 1981-2005, we find strong evidence for the existence of clusters of countries that systematically exchange votes regardless of the quality of their entries. Cultural, geographic, economic and political factors are important determinants of points awarded from one country to another. Other non-quality related factors such as order of appearance, the language of the song and the gender of the performing artist, are also important. There is also a substantial host country effectEurovision, Social Network, Games of Trust

Motivational game design patterns of ’ville games

The phenomenal growth of social network games in the last five years has left many game designers, game scholars, and long-time game players wondering how these games so effectively engage their audiences. Without a strong understanding of the sources of appeal of social network games, and how they relate to the appeal of past games and other human activities, it has proven difficult to interpret the phenomenon accurately or build upon its successes. In this paper we propose and employ a particular approach to this challenge, analyzing the motivational game design patterns in the popular ‘Ville style of game using the lenses of behavioral economics and behavioral psychology, explaining ways these games engage and retain players. We show how such games employ strategies in central, visible ways that are also present (if perhaps harder to perceive) in games with very different mechanics and audiences. Our conclusions point to lessons for game design, game interpretation, and the design of engaging software of any type