A Branch and Cut solver for the maximum stable set problem

This paper deals with the cutting-plane approach to the maximum stable set problem. We provide theoretical results regarding the facet-defining property of inequalities obtained by a known project-and-lift-style separation method called edge-projection, and its variants. An implementation of a Branch and Cut algorithm is described, which uses edge-projection and two other separation tools which have been discussed for other problems: local cuts (pioneered by Applegate, Bixby, Chvátal and Cook) and mod-k cuts. We compare the performance of this approach to another one by Rossi and Smiriglio (Oper. Res. Lett. 28:63–74, 2001) and discuss the value of the tools we have tested.     

Parent‐Child Value Similarity: The Role of Zeitgeist

Reporting a study of German 2‐child families, the article focuses on a neglected issue in value transmission studies: contemporaneous societal context. Parent‐child value similarity depends not only on family characteristics but also on zeitgeist, the modal value climate of a society. To evaluate the role of zeitgeist in value transmission, differences in parent‐child value similarity between families agreeing and disagreeing with the zeitgeist are studied, focusing on a core value of modern societies: hierarchic self‐interest. Results show a weak general zeitgeist effect. A family’s relative position vis‐à‐vis the societal value climate, however, is shown to strongly influence intergenerational similarity in hierarchic self‐interest, families distant from the zeitgeist showing a much higher intergenerational value similarity than families close to the zeitgeist.     

Lorenz Dominance and Non-welfaristic Redistribution

Our concern is for income inequalities that may result from non-welfaristic redistribution schemes. We show that for large classes of income functions Lorenz dominance results can be found in the comparison of two egalitarian equivalent mechanisms. Comparisons of different conditionally egalitarian mechanisms only yield poverty dominance results. In general, no egalitarian equivalent mechanism can be Lorenz dominated by a conditionally egalitarian mechanism. Our analysis stresses the need for accurate empirical estimates of the pre-tax income function and of the distributions of responsibility and compensation characteristics. We thank the Editor, Marc Fleurbaey and two anonymous referees, Geert Dhaene and seminar/conference participants at UAP-workshop (Namur, 2003), ‘Welfarist and non-welfarist approaches to public economics’ (Ghent, 2004), SED (Palma, 2004), SSC&W (Osaka, 2004) and IIPF (Milan, 2004) for helpful comments and suggestions. Financial support from the Federal Public Planning Service Science Policy, Interuniversity Attraction Poles Program – Belgian Science Policy [Contract No. P5/21] is gratefully acknowledged.     

Die soziale Diffrenzierung der Übergangsmuster in den Beruf

Growing risks in working lives and in the transition to the first job are supposed to be a core characteristic of labor market changes in the last two decades. However, they cover heterogeneous phenomena that have to be treated separately. Regarding the job entry process among in-firm training diploma holders, firm shifts, occupational shifts and unemployment represent distinct indicators of non-standard transitions to the first job. The empirical analyses, using data from the German IAB-employment-subsample 1975–1995, show that transition patterns have changed differently in the respective cohorts. The probability of experiencing specific transition patterns strongly depends on social structural as well as occupation-specific characteristics. The strongest risks at labor market entry are associated with combined firm and occupational shifts. There is no coherent evidence of a dominant trend towards less structured job entry patterns.     

Wer Wind s?t, wird Sturm ernten

The present study deals with the theoretical and empirical analysis of the intergenerational transmission of violence. Within the framework of a systematic theory comparison, the self-control theory (Gottfredson und Hirschi 1990) and the social learning theory (Bandura 1979a, b) are used to analyze the mechanisms relating the experience of parental violence in childhood to the use of violence in adolescence (the so-called cycle of violence). The analyses are based on a survey of ninth-graders from schools in Dortmund and Stuttgart (n?=?4583) conducted by the Criminological Research Institute of Lower Saxony (KFN) in 2005. Data analyses are carried out based on linear structural equation modeling. The results reveal that both self-control and social learning processes mediate between the experience of violent parenting and the prevalence of juvenile violence; however, a greater relative share of the cycle of violence can be traced back to social learning processes. The systematic theory comparison points out that the social learning theory provides the superior explanation of the cycle of violence. The results of the study are discussed with regard to their implications for further theory development.     

Options and sequences: Europe’s demographic patterns

It is argued in this lecture that Ryder’s approach to the study of the role of the cohort in social change is too narrow. Cohorts do not only permit change; they actively create the options succeeding cohorts have to choose from. Through its own choice from amongst the options perceived, each cohort both limits and enriches the options of the next. It is through the choice people make with regard to life shaping demographic events that they group themselves into ‘mental’ cohorts. The course of demographic events in Western Europe in the postwar period is difficult to understand if one does not appreciate that these events form a sequence. A sequence generated by the quite specific option(s) each ‘mental’ cohort, through its own choice, created for the next. Current demographic patterns in Europe have to be interpreted in terms of differences in social and cultural heritage of the countries concerned, and in terms of the differences in options perceived and selected.