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AbstractThis article uses computer simulations as a means of assessing two different models for the competition between two languages from the interdisciplinary perspective of complex systems. These models allow for the analysis of the role of bilingual speakers and they consider two of the basic factors determining the use of each language: their relative prestige and the language loyalty of their speakers. Here we assess the effect of these parameters in different social networks, with the aim of contributing to the understanding of the role of bilingualism and social networks in processes of language contact. We first present a qualitative analysis based on a simulation tool that we have designed, in order to visualize the dynamics of the models. Secondly, we consider a qualitative analysis of the role of complex networks, identifying mechanisms for the rapid extinction of a language and for situations of language segregation. Finally, we present a quantitative analysis which shows, counter-intuitively, a transition from a final scenario of language maintenance to one of language shift as language loyalty increases. Other findings are: (i) that the scenario of language coexistence is reduced in the presence of bilingual agents; and (ii) that networks which allow for local effects reduce further the situations for which language maintenance is possible.

We use an agent-based model to investigate the interdependent dynamics between individual agency and emergent socioeconomic structure, leading to institutional change in a generic way. Our model simulates the emergence and exit of institutional units, understood as generic governed social structures. We show how endogenized trust and exogenously given leader authority influences institutional change, i.e., diversity in institutional life-cycles. It turns out that these governed institutions (de)structure in cyclical patterns dependent on the overall evolution of trust in the artificial society, while at the same time, influencing this evolution by supporting social learning. Simulation results indicate three scenarios of institutional life-cycles. Institutions may, (1) build up very fast and freeze the artificial society in a stable but fearful pattern (ordered system); (2) exist only for a short time, leading to a very trusty society (highly fluctuating system); and (3) structure in cyclical patterns over time and support social learning due to cumulative causation of societal trust (complex system).

We use an agent-based model to investigate the interdependent dynamics between individual agency and emergent socioeconomic structure, leading to institutional change in a generic way. Our model simulates the emergence and exit of institutional units, understood as generic governed social structures. We show how endogenized trust and exogenously given leader authority influences institutional change, i.e., diversity in institutional life-cycles. It turns out that these governed institutions (de)structure in cyclical patterns dependent on the overall evolution of trust in the artificial society, while at the same time, influencing this evolution by supporting social learning. Simulation results indicate three scenarios of institutional life-cycles. Institutions may, (1) build up very fast and freeze the artificial society in a stable but fearful pattern (ordered system) ; (2) exist only for a short time, leading to a very trusty society (highly fluctuating system) ; and (3) structure in cyclical patterns over time and support social learning due to cumulative causation of societal trust (complex system).

We use an agent-based model to investigate the interdependent dynamics between individual agency and emergent socioeconomic structure, leading to institutional change in a generic way. Our model simulates the emergence and exit of institutional units, understood as generic governed social structures. We show how endogenized trust and exogenously given leader authority influences institutional change, i.e., diversity in institutional life-cycles. It turns out that these governed institutions (de)structure in cyclical patterns dependent on the overall evolution of trust in the artificial society, while at the same time, influencing this evolution by supporting social learning. Simulation results indicate three scenarios of institutional life-cycles. Institutions may, (1) build up very fast and freeze the artificial society in a stable but fearful pattern (ordered system); (2) exist only for a short time, leading to a very trusty society (highly fluctuating system); and (3) structure in cyclical patterns over time and support social learning due to cumulative causation of societal trust (complex system).

After reviewing the main empirical and theoretical findings about the evolution of inequality and its impact on macroeconomic dynamics, this thesis expands the analysis performed with an agent-based model by Napoletano, Roventini and Gaffard (2016). In the model, which is characterized by heterogeneous households with credit constraints, an inequality shock is introduced. This generates a fall in aggregate demand and income. Scenarios with different degrees of inequality are compared, and what emerges is that higher inequality is associated with more severe recessions. Moreover, a redistributive fiscal policy, in the form of a subsidy, is introduced after the crisis. This policy significantly dampens the fall in aggregate output implied by the inequality shock and is more effective than direct government expenditure in stimulating the economy.

Sovereign default contagion in Eurozone has been under attention since the first problems in Greece at the end of 2009. Despite the improvements in the situation, in particular after several European Central Bank non- conventional monetary policy measures, the roots of the problem and policy prescriptions are still fiercely debated today. Using an agent-based model adapted from Tirole (2015), we simulate sovereign default contagion in a world where countries have random incomes, heterogeneous borrowing behaviors and risk aversion levels and where governments have the possibility to enter in ex-ante agreements to protect against default. We conclude that default contagion can be a very fast and 'destructive' process, higher spending countries tend to have lower disposable incomes and higher risk aversion levels are associated with lower default rates. ; info:eu-repo/semantics/publishedVersion