Evolutionary games on multilayer networks: A colloquium

Networks form the backbone of many complex systems, ranging from the Internet to human societies. Accordingly, not only is the range of our interactions limited and thus best described and modeled by networks, it is also a fact that the networks that are an integral part of such models are often interdependent or even interconnected. Networks of networks or multilayer networks are therefore a more apt description of social systems. This colloquium is devoted to evolutionary games on multilayer networks, and in particular to the evolution of cooperation as one of the main pillars of modern human societies. We first give an overview of the most significant conceptual differences between single-layer and multilayer networks, and we provide basic definitions and a classification of the most commonly used terms. Subsequently, we review fascinating and counterintuitive evolutionary outcomes that emerge due to different types of interdependencies between otherwise independent populations. The focus is on coupling through the utilities of players, through the flow of information, as well as through the popularity of different strategies on different network layers. The colloquium highlights the importance of pattern formation and collective behavior for the promotion of cooperation under adverse conditions, as well as the synergies between network science and evolutionary game theory.Comment: 14 two-column pages, 8 figures; accepted for publication in European Physical Journal

The uneven price impact of energy efficiency ratings on housing segments and implications for public policy and private markets

In the literature, there is extensive, although in some cases inconclusive, evidence on the impact of Energy Performance Certificates (EPC) on housing prices. Nonetheless, the question of whether such an impact is homogenous across residential segments remains highly unexplored. This paper addresses this latter issue utilizing multifamily listing data in metropolitan Barcelona. In doing so, first the entire sample is analyzed using a hedonic model. Second, the sample is split on the basis of a multivariate segmentation. Finally, separated hedonic models are specified again. The results suggest that in general, there is a modest impact of EPC ratings on listing prices, nonetheless it is not homogeneous across housing segments: (1) for the most modern apartments, with state-of-the-art features and active environmental comfort, energy ratings seem to play a null role in the formation of prices; (2) conversely, for the cheapest apartments, apartments boasting the most basic features, and apartments located in low-income areas, the “brown discount” is enormously significant, potentially depreciating the equity of those who have the least resources to carry out an energy retrofit. These results have implications for the assessment of the EPBD and its Spanish transposition, since a very well-intentioned environmental policy could have potentially harmful social repercussions in the absence of corrective measures.Peer ReviewedPostprint (published version

Do Bugs Propagate? An Empirical Analysis of Temporal Correlations Among Software Bugs

The occurrences of bugs are not isolated events, rather they may interact, affect each other, and trigger other latent bugs. Identifying and understanding bug correlations could help developers localize bug origins, predict potential bugs, and design better architectures of software artifacts to prevent bug affection. Many studies in the defect prediction and fault localization literature implied the dependence and interactions between multiple bugs, but few of them explicitly investigate the correlations of bugs across time steps and how bugs affect each other. In this paper, we perform social network analysis on the temporal correlations between bugs across time steps on software artifact ties, i.e., software graphs. Adopted from the correlation analysis methodology in social networks, we construct software graphs of three artifact ties such as function calls and type hierarchy and then perform longitudinal logistic regressions of time-lag bug correlations on these graphs. Our experiments on four open-source projects suggest that bugs can propagate as observed on certain artifact tie graphs. Based on our findings, we propose a hybrid artifact tie graph, a synthesis of a few well-known software graphs, that exhibits a higher degree of bug propagation. Our findings shed light on research for better bug prediction and localization models and help developers to perform maintenance actions to prevent consequential bugs

Discrete Choice with Social Interactions and Endogenous Memberships

This paper tackles the issue of self-selection in social interactions models. I develop a theory of sorting and behavior, when the latter is subject to social influences, extending the model developed by Brock and Durlauf (2001a, 2003) to allow for equilibrium group formation. Individuals choose a group, and a behavior subject to an endogenous social effect. The latter turns out to be a segregating force, and stable equilibria are stratified. The sorting process may induce, inefficiently, multiple behavioral equilibria. Such a theory serves as a means to solve identification and selection problems that may undermine the empirical detection of social effects on individual behavior. I exploit the theoretical model to build a nonlinear (in the social effect) selection correction term. Such a term allows identification, and solves the selection problem that arises when individuals can choose the group whose effect the researcher is trying to disentangle. The resulting econometric model, although relying on strict parametric assumptions, indicates a viable alternative when reliable instrumental variables are not available, or randomized experiments not possible.social interactions, neighborhood effects, sorting, self-selection, nested logit, identification of social effects

"Market Failure and Land Concentration"

Utilizing a 2002 household-level World Bank Survey for rural Turkey, this paper explores the link between concentration of land ownership and rural factor markets. We construct a unique index that measures market malfunctioning based on the neoclassical model linking land and labor endowments through factor markets to household income. We further test whether land ownership concentration affects market malfunctioning. Our empirical investigation supports the claim that factor markets are structurally limited in reducing existing inequalities as a result of land ownership concentration. Our findings show that in the presence of land ownership inequality, malfunctioning rural factor markets result in increased land concentration, increased income inequality, and inefficient resource allocation. This work fills an important empirical gap within the development literature and establishes a positive association between asset inequality and factor market failure.

Repair Matters

Repair has visibly come to the fore in recent academic and policy debates, to the point that ‘repair studies’ is now emerging as a novel focus of research. Through the lens of repair, scholars with diverse backgrounds are coming together to rethink our relationships with the human-made matters, tools and objects that are the material mesh in which organisational life takes place as a political question. This special issue is interested to map the ways that repair can contribute to organisational models alternative to those centered around growth. In order to explore the politics of repair in the context of organization studies, the papers gathered here investigate issues such as: repair as a specific kind of care and socially reproductive labour; repair as a direct intervention into the cornerstones of capitalist economy, such as exchange versus use value, division of work and property relations; repair of infrastructures and their relation with the broader environment; and finally repair as the reflective practice of fixing the organizational systems and institutional habits in which we dwell. What emerges from the diversity of experiences surveyed in this issue is that repair manifests itself as both a regime of practice and counter-conduct that demand an active and persistent engagement of practitioners with the systemic contradictions and power struggles shaping our material world

Contextual Centrality: Going Beyond Network Structures

Centrality is a fundamental network property which ranks nodes by their structural importance. However, structural importance may not suffice to predict successful diffusions in a wide range of applications, such as word-of-mouth marketing and political campaigns. In particular, nodes with high structural importance may contribute negatively to the objective of the diffusion. To address this problem, we propose contextual centrality, which integrates structural positions, the diffusion process, and, most importantly, nodal contributions to the objective of the diffusion. We perform an empirical analysis of the adoption of microfinance in Indian villages and weather insurance in Chinese villages. Results show that contextual centrality of the first-informed individuals has higher predictive power towards the eventual adoption outcomes than other standard centrality measures. Interestingly, when the product of diffusion rate $p$ and the largest eigenvalue $\lambda_1$ is larger than one and diffusion period is long, contextual centrality linearly scales with eigenvector centrality. This approximation reveals that contextual centrality identifies scenarios where a higher diffusion rate of individuals may negatively influence the cascade payoff. Further simulations on the synthetic and real-world networks show that contextual centrality has the advantage of selecting an individual whose local neighborhood generates a high cascade payoff when $p \lambda_1 < 1$. Under this condition, stronger homophily leads to higher cascade payoff. Our results suggest that contextual centrality captures more complicated dynamics on networks and has significant implications for applications, such as information diffusion, viral marketing, and political campaigns

Early Childhood Development and the Law

Early childhood development is a robust and vibrant focus of study in multiple disciplines, from economics and education to psychology and neuroscience. Abundant research from these disciplines has established that early childhood is critical for the development of cognitive abilities, language, and psychosocial skills, all of which turn, in large measure, on the parent-child relationship. And because early childhood relationships and experiences have a deep and lasting impact on a child’s life trajectory, disadvantages during early childhood replicate inequality. Working together, scholars in these disciplines are actively engaged in a national policy debate about reducing inequality through early childhood interventions. Despite the vital importance of this period, the law and legal scholars have been largely indifferent to the dynamics of early childhood development. Doctrine and legislation are rarely developmentally sensitive, lumping children into an undifferentiated category regardless of age. The legal system thus misses key opportunities to combat inequality and foster healthy development for all children. And most legal scholars do not engage with the wealth of interdisciplinary research on early childhood, nor are they part of the interdisciplinary dialogue and policy debates. As a result, that conversation does not include the voices of lawyers and legal scholars, who are uniquely positioned to add critical insights. Remedying this stark disconnect requires doing for law what scholars have done in other disciplines: creating a distinctive field. Accordingly, this Article proposes a subdiscipline of early childhood development and the law. The new field crystallizes a distinctive interest that the legal system must attend to and charts a path for legal scholars to follow for years to come. As with the dawning of fields such as juvenile justice, domestic violence, and elder law, early childhood development and the law will be a focal point for research within the legal academy, a vital bridge to scholars in other disciplines, and an important means for bringing lawyers and legal scholars to the heart of emerging policy debates

“Avoiding the mistakes of the past”: Tower block failure discourse and economies of risk management in London’s Olympic Park

A powerful dystopian imaginary dominates political and cultural representations of Britain’s postwar tower blocks, which continue to be linked to social dysfunction and alienation despite extensive empirical research that challenges such claims. Th is article asks what contested declarations of failure “do” by examining how “tower block failure” is discursively deployed by placemaking professionals—planners, architects, housing managers, regeneration practitioners—engaged in the construction of a “model” mixed-tenure neighborhood in London’s Olympic Park. Examining how the aesthetic fi gure of the “failed” high-rise housing estate is confi gured in relation to the normative models of citizenship and community that infuse social and spatial policy, I argue “failure” is entangled with a speculative, future-oriented economy of risk management, which refracts wider questions about the nonobvious forms that power takes in the neoliberal city