14,128 research outputs found

    Evolutionary Dynamics of Populations with Conflicting Interactions: Classification and Analytical Treatment Considering Asymmetry and Power

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    Evolutionary game theory has been successfully used to investigate the dynamics of systems, in which many entities have competitive interactions. From a physics point of view, it is interesting to study conditions under which a coordination or cooperation of interacting entities will occur, be it spins, particles, bacteria, animals, or humans. Here, we analyze the case, where the entities are heterogeneous, particularly the case of two populations with conflicting interactions and two possible states. For such systems, explicit mathematical formulas will be determined for the stationary solutions and the associated eigenvalues, which determine their stability. In this way, four different types of system dynamics can be classified, and the various kinds of phase transitions between them will be discussed. While these results are interesting from a physics point of view, they are also relevant for social, economic, and biological systems, as they allow one to understand conditions for (1) the breakdown of cooperation, (2) the coexistence of different behaviors ("subcultures"), (2) the evolution of commonly shared behaviors ("norms"), and (4) the occurrence of polarization or conflict. We point out that norms have a similar function in social systems that forces have in physics

    Environmental risk management system design for hazardous waste materials

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    Hazardous materials can be generally deemed as any material which, because of its quantity, concentration, or physical, chemical, or infectious characteristics, may cause, or pose a substantial or potential hazard to human health or the environment. In the context of "sustainable development", most 'materials' could be deemed to be 'hazardous' at some stage of their lifecycle, i.e. from extraction to final disposal.This PhD study develops a decision support system for engineers and policy makers to help limit environmental burden, by reducing the environmental risk and the associated carbon footprint, from the perspective of 'hazardous' materials in product design, through the application of 'game theory' and 'grey theory' etc, as well as various computational approaches, by helping the designer identify novel solutions or mitigation strategies.The thesis starts by introducing the problem situation of the study and identify the research objectives, as well as previous studies have been reviewed in order to set this study in context.Since it is evident that consumers drive the open market, and their preference may be influenced by the carbon footprint label of products, the decision support system proposes an improved carbon labelling scheme to demonstrate the significance of a product‘s carbon footprint in a more visual way. The prototype of the scheme is derived from the concept of 'tolerability of risk', providing a framework by which judgments can be made as to whether society will accept the risk from hazardous materials.Application of game theory for decision support is a novel approach in this study, which aids decision-making by selecting appropriate strategies for both organisations and policy makers to reduce environmental impact. In this context, a game between manufacturers and government in the field of clean production is generated with various game scenarios to reflect the variation trend of strategic actions, and then developed to discuss the reduction of the inherent risk posed by 'hazardous' materials and carbon emissions on the supply chain network.The 'hierarchy of waste' suggests that the most preferable state for sustainability is prevention or the elimination of waste. Although this is not wholly practicable in real terms, the framework gives the importance to waste minimisation and prevention, especially promotes the cleaner production. In addition to strategy selection for mitigating environmental impact, the decision support system also develops an evaluation methodology for application by engineers to aid decision-making on materials selection, thus to improve the materials performances, promote cleaner production and provide better and sustainable products for public consumption

    Three Minimal Market Institutions with Human and Algorithmic Agents: Theory and Experimental Evidence

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    We define and examine three minimal market games (sell-all, buy-sell, and double auction) in the laboratory relative to the predictions of theory. These closed exchange economies have some cash to facilitate transactions, and include feedback. The experiment reveals that (1) the competitive general equilibrium (CGE) and non-cooperative (NCE) models are reasonable anchors to locate most but not all the observed outcomes of the three market mechanisms; (2) outcomes tend to get closer to CGE predictions as the number of players increases; (3) prices and allocations in double auctions deviate persistently from CGE predictions; (4) the outcome paths across the three market mechanisms differ significantly and persistently; (5) importance of market structures for outcomes is reinforced by algorithmic trader simulations; and (6) none of the three markets dominates the others across six measures of performance. Inclusion of some mechanism differences into theory may enhance our understanding of important aspects of markets.Strategic market games, Laboratory experiments, Minimally intelligent agents, Adaptive learning agents, General equilibrium

    Endogenous timing game with non-monotonic reaction functions

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    The aim of this paper is to generalize the endogenous timing game proposed by Hamilton and Slutsky (1990) to cases where the reaction functions are non-motononic, as for instance in the literature on contest. Following the taxonomy of social dilemma provided by Eaton (2004) we consider several pos- sible situations depending on the nature of interactions (plain complementarity or plain substituability and strategic complementarity or strategic substitutability). Under the assumptions of the existence and the uniqueness of the Nash and Stackelberg equilibria, we highlight the presence of a ïŹrst-mover advantage or a second-mover incentive only depending on the nature of cross-eïŹ€ects in players’ payoïŹ€ functions and the slopes of their reaction functions at the Nash equilibrium of the static game. These properties allow us to determine rigorously the Subgame Perfect Nash Equilibrium (SPNE) in the ten studied situations. We establish under which conditions on the nature of interactions a leader emerges at the SPNEïŹrst-mover advantage, endogenous timing game, second-mover incentive, Subgame Perfect Nash Equilibrium

    Fondazione Eni Enrico Mattei

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    This paper develops and tests a dynamic optimization model of fishermen’s investment behavior in a limited-entry fishery. Because exit from limited-entry fisheries may be irreversible, the fisherman has an incentive to maintain the right to fish (whether by actually fishing or by purchasing an annual license) even when the fishery is not profitable, in the hope that conditions may improve. This incentive provides at least a partial explanation for excess capacity in fishing fleets, one of the most pressing fisheries management issues in limited-entry (and other) fisheries around the world. To assess the ability of simple financial models to explain observed investment behavior, we develop a two-factor (price and catch) real options model of the decision problem faced by an active fisherman who has the option to exit a fishery irrevocably. The immediate reason for adopting a two-factor model is the hope of achieving greater predictive power, since obviously both price and catch are important to fishermen’s decisions. Another advantage to this approach is that it provides a mechanism by which investment behavior can be linked in a real options framework to exogenous factors that affect price and catch separately. For example, international market forces are likely to affect price while having a negligible effect on a local fish stock, while local fish stock dynamics may affect catch directly but have little influence on prices (assuming the demand for a particular fish is relatively elastic). In a comparison of model predictions about fishermen’s exit decisions to 5059 observed decisions in the California salmon fishery in the 1990s, 65% of the model’s predictions are correct, suggesting this approach may be useful in the analysis of fishing fleet dynamics.Real option investment, Numerical methods, Fisheries

    Using Data Envelopment Analysis to Evaluate Environmentally Conscious Tourism Management

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    This paper discusses a methodology to assess the performances of tourism management of local governments when economic and environmental aspects are considered as equally relevant. In particular, the focus is on the comparison and efficiency assessment of Italian municipalities located on the costal areas. In order to assess the efficiency status of the considered management units, Data Envelopment Analysis (DEA), a methodology for evaluating the relative efficiency of decision making units, is applied. The efficiency index measure used in DEA analysis accounts for both environmental and economic features correlated to the tourism industry. Further, potential managerial improvements for those areas resulting far from the efficiency frontier can be investigated.Data envelopment analysis, Sustainable tourism

    Fishing Across the Centuries: What Prospects for the Venice Lagoon?

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    Fishing has always been an important activity for those Venetians who live near the Lagoon, and it still enjoys an important economic and social role in the region. Over the last few years, however, the fishing industry has been subject to a profound transformation both in the reduction of the variety and the abundance of the species found in the lagoon, and in the change from a complex and well-structured type of activity to one which has become monospecialist, that is based principally on the fishing of the bivalve Tapes philippinarum (Adam & Reeve). The widespread diffusion of this bivalve and its considerable commercial value have resulted in an increased harvest, initially carried out by hand but now by more sophisticated methods which are capable of obtaining much higher yields. The social, economic and environmental problems resulting from this automated fishing have stimulated research into alternative strategies to manage the alieutic resources of the lagoon which will allow fishing to become a sustainable activity without inflicting long-term environmental damage. This present work will try and prepare the foundations for a system of eco-compatible management, based on an analysis of the functioning of the lagoon’s eco-system, defined as a paralic model, the observation of the traditional forms of fishing practiced over the centuries, a technical analysis of the present typology of lagoon fishing (fishing with fyke nets, “vallicoltura” and fishing of fish fry for rearing, clam fishing (Tapes philippinarum), mussel culture) with particular reference to the species fished, the distribution of the activity throughout the year and the technology employed, to the productivity of the various fishing methods.Venice Lagoon, Fyke nets, Clam Fishing management, Fish Farming
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