Entanglement between Demand and Supply in Markets with Bandwagon Goods

Whenever customers' choices (e.g. to buy or not a given good) depend on others choices (cases coined 'positive externalities' or 'bandwagon effect' in the economic literature), the demand may be multiply valued: for a same posted price, there is either a small number of buyers, or a large one -- in which case one says that the customers coordinate. This leads to a dilemma for the seller: should he sell at a high price, targeting a small number of buyers, or at low price targeting a large number of buyers? In this paper we show that the interaction between demand and supply is even more complex than expected, leading to what we call the curse of coordination: the pricing strategy for the seller which aimed at maximizing his profit corresponds to posting a price which, not only assumes that the customers will coordinate, but also lies very near the critical price value at which such high demand no more exists. This is obtained by the detailed mathematical analysis of a particular model formally related to the Random Field Ising Model and to a model introduced in social sciences by T C Schelling in the 70's.Comment: Updated version, accepted for publication, Journal of Statistical Physics, online Dec 201

A Classification of Paradigmatic Models for Agent-Based Social Simulation

Given the strong interdisciplinary character of Agent-Based Social Simulation (ABSS), and the difficulties related to ambiguous terminological and methodological assumptions, there is an increasing need to make more explicit the modelling paradigm underlying each research paper or project. In this paper we propose a classification of paradigmatic models in ABSS, which characterise different ontological assumptions and pragmatic criteria with respect to their targets. The classification is composed by different classes of models at different levels of abstraction, in a layered architecture that enables switching among levels. Each class is based on different kinds of assumptions, which possibly call for different logics of scientific research. The taxonomy was well validated with researchers in the field. It seems a good analytical tool for characterising or comparing models according to various criteria, such as methodological, philosophical, or simply pragmatic and usability criteria

Efeitos da monensina no desempenho de bezerras leiteiras em crescimento Effects of monensin on growing dairy heifers performance

Foi estudado o efeito da suplementação de monensina sobre o desempenho de 32 novilhas Holandesas em crescimento, com peso médio de 84 kg, durante quatro meses . Os animais suplementados com monensina apresentaram maior peso e perímetro torácico aos 90 e 120 dias de experimentação, maior ganho de peso, mostrando um valor de 26,56% maior do que os animais controle. Não foi observada diferença no comprimento corporal e glicose sangüínea, enquanto a altura na cernelha apresentou tendência a valores mais altos nos animais suplementados. Concluiu-se que a suplementação de monensina resultou em maior desenvolvimento dos animais, podendo proporcionar precocidade reprodutiva e produtiva de novilhas leiteiras de reposição.<br>The performance of 32 growing Holstein heifers, with average weight of 84 kg and supplemented with monensin, during four months, was studied. The animals supplemented with monensin presented higher weight and hearth girth at 90 and 120 days of experiment, higher weight gain, with value of 26.56% superior than the control animals. No difference was observed for the corporal length, plasma glucose and the height values. The animals fed monensin presented higher height values. The animals supplemented with monensin showed better development. The use of monensin provided reproductive and productive precocity for the replacement dairy heifers

Information-driven coordination: experimental results with heterogeneous individuals

Heterogeneous players, Threshold of participation, Coordination game, Multiple Nash equilibria, Experiments, Learning,