11,948 research outputs found

    Tracing Equilibrium in Dynamic Markets via Distributed Adaptation

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    Competitive equilibrium is a central concept in economics with numerous applications beyond markets, such as scheduling, fair allocation of goods, or bandwidth distribution in networks. Computation of competitive equilibria has received a significant amount of interest in algorithmic game theory, mainly for the prominent case of Fisher markets. Natural and decentralized processes like tatonnement and proportional response dynamics (PRD) converge quickly towards equilibrium in large classes of Fisher markets. Almost all of the literature assumes that the market is a static environment and that the parameters of agents and goods do not change over time. In contrast, many large real-world markets are subject to frequent and dynamic changes. In this paper, we provide the first provable performance guarantees of discrete-time tatonnement and PRD in markets that are subject to perturbation over time. We analyze the prominent class of Fisher markets with CES utilities and quantify the impact of changes in supplies of goods, budgets of agents, and utility functions of agents on the convergence of tatonnement to market equilibrium. Since the equilibrium becomes a dynamic object and will rarely be reached, our analysis provides bounds expressing the distance to equilibrium that will be maintained via tatonnement and PRD updates. Our results indicate that in many cases, tatonnement and PRD follow the equilibrium rather closely and quickly recover conditions of approximate market clearing. Our approach can be generalized to analyzing a general class of Lyapunov dynamical systems with changing system parameters, which might be of independent interest

    Assessing the Economic Impacts of Climate Change. An Updated CGE Point of View

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    The present research describes a climate change integrated impact assessment exercise, whose economic evaluation is based on a CGE approach and modeling effort. Input to the CGE model comes from a wide although still partial set of up-to-date bottom-up impact studies. Estimates indicate that a temperature increase of 1.92°C compared to pre-industrial levels in 2050 could lead to global GDP losses of approximately 0.5% compared to a hypothetical scenario where no climate change is assumed to occur. Northern Europe is expected to benefit from the evaluated temperature increase (+0.18%), while Southern and Eastern Europe are expected to suffer from the climate change scenario under analysis (-0.15% and -0.21% respectively). Most vulnerable countries are the less developed regions, such as South Asia, South-East Asia, North Africa and Sub-Saharan Africa. In these regions the most exposed sector is agriculture, and the impact on crop productivity is by far the most important source of damages. It is worth noting that the general equilibrium estimates tend to be lower, in absolute terms, than the bottom-up, partial equilibrium estimates. The difference is to be attributed to the effect of market-driven adaptation. This partly reduces the direct impacts of temperature increases, leading to lower damage estimates. Nonetheless these remain positive and substantive in some regions. Accordingly, market-driven adaptation cannot be the solution to the climate change problem.Computable General Equilibrium Modeling, Impact Assessment, Climate Change

    The Minority of Three-Game: An Experimental and Theoretical Analysis

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    We report experimental and theoretical results on the minority of three-game where three players have to choose one of two alternatives independently and the most rewarding alternative is the one chosen by a single player. This coordination game has many asymmetric equilibria in pure strategies that are non strict and payoff-asymmetric, and a unique symmetric mixed strategy equilibrium in which each player's behavior is based on the toss of a fair coin. We show that such a straightforward behavior is predicted by Harsanyi and Selten's (1988) equilibrium selection theory as well as alternative solution concepts like impulse balance equilibrium and sampling equilibrium. Our results indicate that participants rely on various decision rules, and that only a quarter of them decide according to the toss of a fair coin. Reinforcement learning is the most successful decision rule as it describes best the behavior of about a third of our participants.Coordination, Minority game, Mixed strategy, Learning models, Experiments

    Reviewing agent-based modelling of socio-ecosystems: a methodology for the analysis of climate change adaptation and sustainability

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    The integrated - environmental, economic and social - analysis of climate change calls for a paradigm shift as it is fundamentally a problem of complex, bottom-up and multi-agent human behaviour. There is a growing awareness that global environmental change dynamics and the related socio-economic implications involve a degree of complexity that requires an innovative modelling of combined social and ecological systems. Climate change policy can no longer be addressed separately from a broader context of adaptation and sustainability strategies. A vast body of literature on agent-based modelling (ABM) shows its potential to couple social and environmental models, to incorporate the influence of micro-level decision making in the system dynamics and to study the emergence of collective responses to policies. However, there are few publications which concretely apply this methodology to the study of climate change related issues. The analysis of the state of the art reported in this paper supports the idea that today ABM is an appropriate methodology for the bottom-up exploration of climate policies, especially because it can take into account adaptive behaviour and heterogeneity of the system's components.Review, Agent-Based Modelling, Socio-Ecosystems, Climate Change, Adaptation, Complexity.

    Computer simulations, mathematics and economics

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    Economists lise different kinds of computer simulation. However, there is little attention on the theory of simulation, which is considered either a technology or an extension of mathematical theory or, else, a way of modelling that is alternative to verbal description and mathematical models. The paper suggests a systematisation of the relationship between simulations, mathematics and economics. In particular, it traces the evolution of simulation techniques, comments some of the contributions that deal with their nature, and, finally, illustrates with some examples their influence on economie theory. Keywords: Computer simulation, economie methodology, multi-agent programming techniques.

    Carbon Abatement Costs: Why the Wide Range of Estimates?

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    Estimates of marginal abatement costs for reducing carbon emissions derived from major economic-energy models vary widely. Controlling for policy regimes, we use meta-analysis to examine the importance of structural modeling choices in explaining differences in estimates. The analysis indicates that particular assumptions about perfectly foresighted consumers and Armington trade elasticities generate lower estimates of marginal abatement costs. Other choices are associated with higher cost estimates, including perfectly mobile capital, inclusion of a backstop technology, and greater disaggregation among regions and sectors. Some features, such as greater technological detail, seem less significant. Understanding the importance of key modeling assumptions, as well as the way the models are used to estimate abatement costs, can help guide the development of consistent modeling practices for policy evaluation.climate models, carbon tax

    The minority of three-game: an experimental and theoretical analysis

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    We report experimental results on the minority of three-game, where three players choose one of two alternatives and the most rewarding alternative is the one chosen by a single player. This coordination game has many asymmetric equilibria in pure strategies that are non-strict and payoff-asymmetric and a unique symmetric mixed strategy equilibrium in which each player’s behavior is based on the toss of a fair coin. This straightforward behavior is predicted by equilibrium selection, impulse-balance equilibrium, and payoff-sampling equilibrium. Experimental participants rely on various decision rules, and only a quarter of them perfectly randomize

    Riding the wave: Distributional properties and process explanations of merger and acquisition waves

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    Although Mergers and Acquisitions (M&A) are potential value-creation opportunities, why they tend to occur in waves is a mystery to scholars and managers alike. Most models of M&A waves are unilevel, reductionist, and Gaussian, whereas wave patterns are arguably multi-level, emergent, and non-normally distributed. Using complexity theory, I interpret waves as emergent expressions of a self-organized critical ecology of firms conceptualized as a complex adaptive system. My observation that aggregate U.S. M&A waves from 1895 to 2008 are power-law-distributed lends support. The view that waves are self-organized critical phenomena, similar to earthquakes and avalanches, facilitates integration of prior wave theories. I then employ process-tracing to generate a historical narrative of the Great Merger Wave of 1898-1903, from which I obtain a robust process for waves consistent with a CAS interpretation of these phenomena: (1) a privatizing, market-expanding and financially innovating transportation network generates (2a) laissez-faire regulation, (2b) economic competition, and (2c) financial arbitrage, leading to (3) a burst of consolidation. My process explanation explains the power law's emergence, and may help to understand better the process dynamics of M&A waves

    Time to rebuild and reaggregate fluctuations: Minsky, complexity and agent-based modelling

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