A successive approximation algorithm for the multiple knapsack problem

It is well-known that the multiple knapsack problem is NP-hard, and does not admit an FPTAS even for the case of two identical knapsacks. Whereas the 0-1 knapsack problem with only one knapsack has been intensively studied, and some effective exact or approximation algorithms exist. A natural approach for the multiple knapsack problem is to pack the knapsacks successively by using an effective algorithm for the 0-1 knapsack problem. This paper considers such an approximation algorithm that packs the knapsacks in the nondecreasing order of their capacities. We analyze this algorithm for 2 and 3 knapsack problems by the worst-case analysis method and give all their error bounds.     

自由主义的理论困境及现实危机

自由主义的理论困境主要有个人优先与社会优先之争、权利与善之争、自由至上与多元价值之争等3个方面,这种困境不仅来自于理论与实践的冲突,更多来自于资本主义生产方式,并由此使得社会性危机成为资本主义社会的梦魇,研究自由主义的理论困境对于回应和反击西方意识形态的渗透,维护马克思主义意识形态在社会主义核心价值体系中的引领作用具有重要的战略意义和时代价值。     

Empowering Lesbian and Gay Foster Adolescents Through Mentoring Relationships

This article discusses a mentoring model as a resource for lesbian and gay adolescents in foster care. Interview data collected in a national study of foster adolescent mentoring programs led to the identification of elements of succesful programs. The authors apply these elements to the design of a model mentoring program for lesbian and gay adolescents. Such a model program would help to alleviate problems that are related to isolation, stigmatization, and lack of positive lesbian and gay role models. Selected lesbian and gay youth vignettes are described and implications drawn for program development.     

The case for critical social gerontology in social work education and older women1

This article argues the case for the application of critical social gerontological theory and research to social work education and older women, both as a way of heightening student social workers' awareness and understanding of the complex and diverse experiences of older women who make use of personal social services AND to develop anti‐ageist and anti‐sexist practice. In presenting this ‘case for social gerontology’, the paper will draw on findings from the author's recent research with older widows.     

Multiple Migration Flows of Romanians

Abstract

Most studies on international migration examine population movement between a country of origin and a destination. This article aims to show that migrants often change destinations, a less studied pattern of ‘multiple migrations’. This article explores how such migration occurs and analyses the variables accounting for it. Drawing on qualitative fieldwork research amongst Romanian migrants in Portugal, the article concludes that the growth in multiple migrations of Romanian migrants throughout Europe can be explained by a combination of migration policies and social networks, mediated by migrants’ level of education and type of occupation at the destination.     

Unemployment Protection and Family Policy at the Turn of the 21st Century: A Dynamic Approach to Welfare Regime Theory

This article contributes to the welfare state regime literature from a substantive and methodological perspective. At a very abstract level we confirm the relevance of the welfare state regime theory and stability for the period from 1971 to the end of the 1990s. However, by analyzing family policy and unemployment protection, we observe a dual transformation of the welfare state, consisting of a trend towards a ‘socialization’ of family policies and a retrenchment in unemployment insurance benefits. Our Multiple Correspondence Analysis (MCA) of the two policy domains captures the multi‐dimensionality of the decommodification and defamilialization concepts and visualizes welfare state developments over time in a Cartesian space. This dynamic analysis provides us with a nuanced understanding of welfare state regime stability and change.     

Inference of Signs of Interaction Effects in Simultaneous Games With Incomplete Information

This paper studies the inference of interaction effects in discrete simultaneous games with incomplete information. We propose a test for the signs of state‐dependent interaction effects that does not require parametric specifications of players' payoffs, the distributions of their private signals, or the equilibrium selection mechanism. The test relies on the commonly invoked assumption that players' private signals are independent conditional on observed states. The procedure is valid in (but does not rely on) the presence of multiple equilibria in the data‐generating process (DGP). As a by‐product, we propose a formal test for multiple equilibria in the DGP. We also implement the test using data on radio programming of commercial breaks in the United States, and infer stations' incentives to synchronize their commercial breaks. Our results support the earlier finding by Sweeting (2009) that stations have stronger incentives to coordinate and air commercials at the same time during rush hours and in smaller markets.     

Extreme ranking analysis in robust ordinal regression

We extend the principle of robust ordinal regression with an analysis of extreme ranking results. In our proposal, we consider the whole set of instances of a preference model that is compatible with preference information provided by the DM. We refer to both, the well-known UTA^GMS method, which builds the set of general additive value functions compatible with DM's preferences, and newly introduced in this paper PROMETHEE^GKS, which constructs the set of compatible outranking models via robust ordinal regression. Then, we consider all complete rankings that follow the use of the compatible preference models, and we determine the best and the worst attained ranks for each alternative. In this way, we are able to assess its position in an overall ranking, and not only in terms of pairwise comparisons, as it is the case in original robust ordinal regression methods. Additionally, we analyze the ranges of possible comprehensive scores (values or net outranking flows). We also discuss extensions of the presented approach on other multiple criteria problems than ranking. Finally, we show how the presented methodology can be applied in practical decision support, reporting results of three illustrative studies.     

An inventory model with random discount offerings

We consider an inventory model in which a supplier makes deal offers with random discount prices at random points in time. Assuming that discount offerings follow a Poisson process and discount price is a discrete random variable with a known distribution, we propose a continuous-review control policy for the model and derive optimality conditions for the policy parameters. The model is then extended to the case of multiple suppliers that offer discount deals with supplier-specific Poisson processes and discount prices. Numerical examples are presented to demonstrate cost savings due to discount offers.     

多元智能理论指导下的英美概况网络教学策略

多元智能理论是一种全新的智能观,它的兴起给网络课程教学设计带来无限生机.本文从多元智能理论出发,探讨了多元智能理论指导下的英美概况网络教学的优势及教学策略.