arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1407.7153physics.soc-phq-fin.GN
收藏

具有极值动力的简单交换模型的财富分布

Wealth distribution of simple exchange models coupled with extremal dynamics

N. Bagatella-Flores, M. Rodriguez-Achach, H. F. Coronel-Brizio, A. R. Hernandez-Montoya

摘要:

间断平衡(PE)指出,经过长时间的进化静止,物种进化可以在短时间内发生,突然的分化使新物种出现,一些物种灭绝。本文介绍并研究了间断均衡对两种不同的资产交换模型的影响:庭院销售模型(YS,赢家得到一个贫穷玩家财富的随机分数)和盗窃和欺诈模型(TF,赢家得到一个失败者财富的随机分数)。由此产生的财富分配的特点是使用基尼指数。为了做到这一点,我们认为PE作为一个扰动的概率$ρ$被应用。我们比较了两种模型中$ρ$的不同增加值下的基尼指数结果。我们发现,在TF模型的情况下,基尼系数随着扰动$ρ$的增加而减小,并不表现出与代理数量的依赖性。而对于YS,我们观察到发生在$ρ_c=0.79$周围的相变。对于扰动$ρ<ρ_c$,基尼指数随着时间的增加而达到1的值(一个极端的财富凝聚状态),而对于大于或等于$ρ_c$的扰动,基尼指数变为不同的1,避免系统达到这种极端状态。我们表明,这两个简单的交换模型加上PE动态给出更现实的结果。特别是对于YS,我们观察到财富分配的幂低衰减。

英文摘要:

Punctuated Equilibrium (PE) states that after long periods of evolutionary quiescence, species evolution can take place in short time intervals, where sudden differentiation makes new species emerge and some species extinct. In this paper, we introduce and study the effect of punctuated equilibrium on two different asset exchange models: The yard sale model (YS, winner gets a random fraction of a poorer player's wealth) and the theft and fraud model (TF, winner gets a random fraction of the loser's wealth). The resulting wealth distribution is characterized using the Gini index. In order to do this, we consider PE as a perturbation with probability $ρ$ of being applied. We compare the resulting values of the Gini index at different increasing values of $ρ$ in both models. We found that in the case of the TF model, the Gini index reduces as the perturbation $ρ$ increases, not showing dependence with the agents number. While for YS we observe a phase transition which happens around $ρ_c=0.79$. For perturbations $ρ<ρ_c$ the Gini index reaches the value of one as time increases (an extreme wealth condensation state), whereas for perturbations bigger or equal than $ρ_c$ the Gini index becomes different to one, avoiding the system reaches this extreme state. We show that both simple exchange models coupled with PE dynamics give more realistic results. In particular for YS, we observe a power low decay of wealth distribution.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑