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dc.contributor.advisorRuckenstein, Andrei E.en_US
dc.contributor.authorZubillaga Herrera, Bernardo Joséen_US
dc.date.accessioned2020-11-20T18:54:31Z
dc.date.available2020-11-20T18:54:31Z
dc.date.issued2020
dc.identifier.urihttps://hdl.handle.net/2144/41703
dc.description.abstractThis work proposes a three-state microscopic opinion formation model based on the stochastic dynamics of the three-state majority-vote model. In order to mimic the heterogeneous compositions of societies, the agent-based model considers two different types of individuals: noise agents and contrarians. We propose an extension of the model for the simulation of the dynamics of financial markets. Agents are represented as nodes in a network of interactions and they can assume any of three distinct possible states (e.g. buy, sell or remain inactive, in a financial context). The time evolution of the state of an agent is dictated by probabilistic dynamics that include both local and global influences. A noise agent is subject to local interactions, tending to assume the majority state of its nearest neighbors with probability 1-q (dissenting from it with a probability given by the noise parameter q). A contrarian is subject to a global interaction with the society as a whole, tending to assume the state of the global minority of said society with probability 1 -q (dissenting from it with probability q). The stochastic dynamics are simulated on complex networks of different topologies, including square lattices, Barabási-Albert networks, Erdös-Rényi random graphs and small-world networks built according to a link rewiring scheme. We perform Monte Carlo simulations to study the second-order phase transition of the system on small-world networks. We perform finite-size scaling analysis and calculate the phase diagram of the system, as well as the standard critical exponents for different values of the rewiring probability. We conclude that the rewiring of the lattice drives the system to different universality classes than that of the three-state majority-vote model on a two dimensional square lattice. The model’s extension for financial markets exhibits the typical qualitative and quantitative features of real financial time series, including heavy-tailed return distributions, volatility clustering and long-term memory for the absolute values of the returns. The histograms of returns are fitted by means of coupled exponential distributions, quantitatively revealing transitions between leptokurtic, mesokurtic and platykurtic regimes in terms of a nonlinear statistical coupling and a shape parameter which describe the complexity of the system.en_US
dc.language.isoen_US
dc.subjectStatistical physicsen_US
dc.subjectComplex networksen_US
dc.subjectComplex systemsen_US
dc.subjectEconophysicsen_US
dc.subjectOpinion formation dynamicsen_US
dc.subjectPhase transitionsen_US
dc.subjectSociophysicsen_US
dc.titleThe statistical mechanics of societies: opinion formation dynamics and financial marketsen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2020-11-19T23:02:04Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplinePhysicsen_US
etd.degree.grantorBoston Universityen_US
dc.identifier.orcid0000-0001-9917-9415


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