现代不确定性理论的比较研究

不确定性分析是现代经济理论产生的前提.奈特是不确定性理论的开创者,在对风险和不确定性划分的基础上,奈特解释了利润的来源,并对企业的性质进行了界定.科斯在分析企业理论时,对奈特的不确定性理论进行了批判.威廉姆森是继科斯之后集交易成本理论之大成者.无论是奈特、科斯或是威廉姆森都重视不确定性对企业的影响,但他们三者在不确定性的内涵、理论地位及分析方法上都存在不同.     

Should refusal to sell be illegal?

We analyse a private firm's decision of whether to refuse to sell to a particular group of consumers whose interaction with other consumers generates negative externalities. The literature has rarely incorporated this motive directly into the firm's profit-maximisation problem. Discriminatory refusal-to-sell policies can increase profits and consumer utility among those affected by the negative externality. Of course it also reduces utility among consumers who are refused, raising the possibility of an indeterminate effect on social welfare. We obtain a stark and rather surprising result: The refusal-to-sell policy is socially optimal whenever it is individually optimal for a profit-maximising firm to adopt such a policy. No legislation or regulation is required from a social-welfare perspective (under the assumptions used in the specification of the social welfare function). We prove this result analytically for the case of linear demand functions. Numerical simulations show that the result also holds for constant-price-elasticity demand functions.     

On the Lp error of the Grenander-type estimator in the Cox model

We consider the Cox regression model and study the asymptotic global behavior of the Grenander-type estimator for a monotone baseline hazard function. This model is not included in the general setting of Durot (2007). However, we show that a similar central limit theorem holds for L_p-error of the Grenander-type estimator. As an illustration of application of our main result, we propose a test procedure for a Weibull baseline distribution, based on the L_p-distance between the Grenander estimator and a parametric estimator of the baseline hazard. Simulation studies are performed to investigate the performance of this test.     

Continuous‐time mean–variance portfolio selection: A reinforcement learning framework

We approach the continuous‐time mean–variance portfolio selection with reinforcement learning (RL). The problem is to achieve the best trade‐off between exploration and exploitation, and is formulated as an entropy‐regularized, relaxed stochastic control problem. We prove that the optimal feedback policy for this problem must be Gaussian, with time‐decaying variance. We then prove a policy improvement theorem, based on which we devise an implementable RL algorithm. We find that our algorithm and its variant outperform both traditional and deep neural network based algorithms in our simulation and empirical studies.     

我国大宗商品出口需求价格弹性与最优出口关税——以稀土为例

出口税作为最常用的一种出口限制措施近来在各国贸易政策中屡见不鲜。现有文献对依据"勒纳对称定理"得到的最优关税结论存有异议。文章首先研究了大国作为唯一出口国情况下最优出口关税的决定,认为已有文献关于最优出口税结果不同的根源在于假设差异所致,然后,分析了非唯一出口国情况下大国最优出口关税的决定,最优出口关税和出口商品的需求价格弹性、本国出口所占世界市场份额和其他出口国的供给弹性有关,最后,以稀土为例,采用面板数据模型测算了我国稀土出口的需求价格弹性和需求收入弹性,并得到了我国稀土出口的最优关税。     

A Post-Keynesian Response to Piketty's ‘Fundamental Contradiction of Capitalism’

In Capital in the Twenty-First Century, Thomas Piketty presents a rich set of data that deals with income and wealth distribution, output-wealth dynamics and rates of return. He also proposes some ‘laws of capitalism’. At the core of his argument lies the ‘fundamental inequality of capitalism’, an empirical regularity stating that the rate of return on wealth is greater than the growth rate of the economy. This simple construct allows him to conclude that increasing wealth (and income) inequality is an inevitable outcome of capitalism. While we share some of his conclusions, we will highlight some shortcomings of his approach based on a Cambridge post-Keynesian growth-and-distribution model. The paper makes four points. First, r?>?g is not necessarily associated with increasing inequality in functional distribution. Second, Piketty succumbs to a fallacy of composition when he claims that a necessary condition for r?>?g is that capitalists save a large share of their capital income. Third, post-Keynesians can learn from Piketty's insights about personal income distribution and incorporate them into their models. Fourth, we reiterate the post-Keynesian argument that a well-behaved aggregate production function does not exist and cannot explain income distribution.     

Communication in repeated network games with imperfect monitoring

I consider repeated games with private monitoring played on a network. Each player has a set of neighbors with whom he interacts: a player's payoff depends on his own and his neighbors' actions only. Monitoring is private and imperfect: each player observes his stage payoff but not the actions of his neighbors. Players can communicate costlessly at each stage: communication can be public, private or a mixture of both. Payoffs are assumed to be sensitive to unilateral deviations. First, for any network, a folk theorem holds if some Joint Pairwise Identifiability condition regarding payoff functions is satisfied. Second, a necessary and sufficient condition on the network topology for a folk theorem to hold for all payoff functions is that no two players have the same set of neighbors not counting each other.     

Efficient political contributions with conditional Coasian contracts

The externalities associated with political contributions imply agents choose a socially inefficient level. A typical market solution to these externalities would involve Coase bargaining where agents form contracts with payments conditional on the actions of others. These contracts, however, are hard to enforce because political contributions can be unobservable or unmeasurable. In this study, we modify these Coasian contracts, making the payments conditional on the outcome of the political election. We show the agents that form these contracts contribute the socially efficient amount.     

一个有界函数命题的推广

应用Taylor公式、不等式的性质及数学归纳法,经过逻辑推理得到一个真命题。     

基于Falvey模型的H-O第三定理及其政策意义研究

利用Falvey模型推出H-O第三定理及其丰富的政策意义,即劳动丰富的国家或地区出口国际竞争力低的商品,资本丰富的国家或地区出口国际竞争力高的商品。提高工资率或者降低资本租金率可以扩大该国或该地区产品的国际竞争力区域,但不会逆转国际竞争力现状。只有提高工资率和降低资本租金率的政策同时实施,才能够逆转该国或该地区的国际竞争力现状。辽宁省农产品国际竞争力现状基本上支持了H-O第三定理及其政策意义。