Beliefs,payoffs, information: On the robustness of the BDP property in models with endogenous beliefs

Neeman (2004) and Heifetz and Neeman (2006) have shown that, in auctions with incomplete information about payoffs, full surplus extraction is only possible if agents’ beliefs about other agents are fully informative about their own payoff parameters. They argue that the set of incomplete-information models with common priors that satisfy this so-called BDP property (“beliefs determine preferences”) is negligible. In contrast, we show that, in models with finite-dimensional abstract type spaces, the set of belief functions with this property is topologically generic in the set of all belief functions. Our result implies genericity of (non-common or common) priors with the BDP property.     

基于格网尺度的密云水库区域“三生”空间功能测度与时空变化分析

[目的]为有目标地进行土地利用调整、科学合理促进区域生态景观建设和生态环境保护提供参考。[方法]文章以北京市密云水库区域为研究对象,基于遥感影像解译的1993年和2016年土地利用现状图,分析了研究区土地利用类型的面积变化和相互转换特征;在剖析土地多功能性的基础上,构建了不同土地利用类型的生产、生活、生态用地的功能指数,从而对土地利用类型进行了"三生"空间的划分,并基于格网尺度揭示了研究区域"三生"空间时空变化规律。[结果](1) 1993—2016年密云水库区域土地利用类型主要为林地和水域,其面积变化以耕地、林地、草地和园地为主。其中,耕地和草地的面积减少,主要转换为园地;林地面积增加,主要来源于草地和荒土地;园地面积增加,主要来源于林地、耕地和草地;林地和园地之间相互转化的面积较大。(2)研究期间,密云水库区域"三生"空间相对稳定,生态功能一直是研究区域的主导功能,1993—2016年生产空间和生活空间扩张,生态空间略有缩小;不同级别保护区范围内的土地利用变化规律与总体变化较为一致,二级保护区范围内的变化相对大。[结论]研究结果可以为精细化评估区域"三生"空间时空变化做参考,并能服务于区域土地利用结构调整和可持续利用及区域生态建设。     

Using GIS to visualise and evaluate student travel behaviour

Using GIS to evaluate travel behaviour is an important technique to increase our understanding of the relationship between accessibility and transport demand. In this paper, the activity space concept was used to identify the nature of participation in activities (or lack of it) amongst a group of students using a 2 day travel-activity diary. Three different indicators such as the number of unique locations visited, average daily distance travelled, and average daily activity duration were used to measure the size of activity spaces. These indicators reflect levels of accessibility, personal mobility, and the extent of participation, respectively. Multiple regression analyses were used to assess the impacts of students socio-economic status and the spatial characteristics of home location. Although no differences were found in the levels of accessibility and the extent of participation measures, home location with respect to a demand responsive transport (DRT) service was found to be the most important determinant of their mobility patterns. Despite being able to travel longer distances, students who live outside of the DRT service area were found to be temporally excluded from some opportunities. Student activity spaces were also visualised within a GIS environment and a spatial analysis was conducted to underpin the evaluation of the performance of the DRT. This approach was also used to identify the activity spaces of individuals that are geographically excluded from the service. Evaluation of these results indicated that although the service currently covers areas of high demand, 90% of the activity spaces remained un-served by the DRT service. Using this data six new routes were designed to meet the coverage goal of public transport based on a measure of network impedance based on inverse activity density. Following assessment of public transport service coverage, the study was extended using a spatial multi criteria evaluation (SMCE) technique to assess the effect of service provision on patronage.     

Gender,leisure and sport: a case-study of young people of South Asian descent

Questions of embodiment are to be crucial in shaping the dynamics of social inclusion and exclusion. To explore the way that these dynamics shape the use of leisure spaces, this paper examines the mediation of Carnage UK events, organised mass student excursions around spaces of nightlife that have proved controversial in many British towns and cities. It is suggested in this paper that the discursive framing of Carnage UK events reflects specific social anxieties about disorderly bodies, invoking distinctions based on classed, sexed and gendered notions of respectability and desirability. Highlighting themes relating to carnivalesque and excessive bodies, it is concluded that conflicts over the use of leisure spaces need to be understood in relation to representations of specific social groups as figures of both desire and disgust. In making this argument, the paper alights on the student as a key figure in contemporary debates concerning nightlife, leisure and consumption.     

The cheapest hedge

Investors often wish to insure themselves against the payoff of their portfolios falling below a certain value. One way of doing this is by purchasing an appropriate collection of traded securities. However, when the derivatives market is not complete, an investor who seeks portfolio insurance will also be interested in the cheapest hedge that is marketed. Such insurance will not exactly replicate the desired insured-payoff, but it is the cheapest that can be achieved using the market.Analytically, the problem of finding a cheapest insuring portfolio is a linear programming problem. The present paper provides an alternative portfolio dominance approach to solving the minimum-premium insurance portfolio problem. This affords remarkably rich and intuitive insights to determining and describing the minimum-premium insurance portfolios.     

Epistemic equivalence of extended belief hierarchies

In this paper, we introduce a notion of epistemic equivalence between hierarchies of conditional beliefs and hierarchies of lexicographic beliefs, thus extending the standard equivalence results of Halpern (2010) and Brandenburger et al. (2007) to an interactive setting, and we show that there is a Borel surjective function, mapping each conditional belief hierarchy to its epistemically equivalent lexicographic belief hierarchy. Then, using our equivalence result we construct a terminal type space model for lexicographic belief hierarchies. Finally, we show that whenever we restrict attention to full-support beliefs, epistemic equivalence between a lexicographic belief hierarchy and a conditional belief hierarchy implies that an arbitrary Borel event is commonly assumed under the lexicographic belief hierarchy if and only if it is commonly strongly believed under the conditional belief hierarchy. This is the first result in the literature directly linking common assumption in rationality (Brandenburger et al., 2008) with common strong belief in rationality (Battigalli and Siniscalchi, 2002).     

Vitali—Hahn—Sakes-Nikodym收敛定理的一个推广

证明了有效代数上的一个子级数收敛定理，把vitali—Hahn—Sakes-Nikodym收敛定理从口一代数推广到有效代数上，同时得到另一个测度收敛定理．     

Development Regimes,Scales and State Spatial Restructuring: Change and Continuity in the Production of Urban Space in Metropolitan Rio de Janeiro,Brazil

Using the experience of metropolitan Rio de Janeiro, this article contributes to the broader debate on development regimes, rescaling and state spatial restructuring in Brazil, and its specificities in relation to the international discussion on the transformations in Atlantic Fordism. I argue that the transition from a (peripheral) development state to a competitive and rescaled regime has been accompanied by important continuities. Legitimized through discourses around development poles and trickle‐down effects, the national‐developmental regime has systematically promoted some spaces as opposed to others, without much emphasis on the social and environmental dimensions of spatial policies. The emerging competitive state spatial regime, whether in its neoliberalized, or its more recent ‘rolled‐out’ national‐developmental version, is merely expected to aggravate the historical socio‐environmental contradictions in the production of space. Moreover, scale has proven contested and strategic‐relational, both molding and being influenced by actors that seek to use scalar politics to reach their interests. My analysis suggests that, within this scenario, neither economic growth, nor regulatory and institutional strengthening, nor financial resources are likely to produce structural transformation in the inherited spaces of Greater Rio de Janeiro.