Expected Utility Consistent Extensions of Preferences

We consider the problem of extending a (complete) order over a set to its power set. The extension axioms we consider generate orderings over sets according to their expected utilities induced by some assignment of utilities over alternatives and probability distributions over sets. The model we propose gives a general and unified exposition of expected utility consistent extensions whilst it allows to emphasize various subtleties, the effects of which seem to be underestimated – particularly in the literature on strategy-proof social choice correspondences.      

A Markov Chain Model for an EMS System with Repositioning

We propose and analyze a two‐dimensional Markov chain model of an Emergency Medical Services system that repositions ambulances using a compliance table policy, which is commonly used in practice. The model is solved via a fixed‐point iteration. We validate the model against a detailed simulation model for several scenarios. We demonstrate that the model provides accurate approximations to various system performance measures, such as the response time distribution and the distribution of the number of busy ambulances, and that it can be used to identify near‐optimal compliance tables. Our numerical results show that performance depends strongly on the compliance table that is used, indicating the importance of choosing a well‐designed compliance table.     

Market Impact on IT Security Spending

Traditionally, IT security investment decisions are made in isolation. However, as firms that compete for customers in an industry are closely interlinked, a macro perspective is needed in analyzing these decisions. We utilize the notions of direct‐ and cross‐risk elasticity to describe the customer response to adverse IT security events in the firm and competitor, respectively, thus allowing us to analyze optimal security investment decisions. Examining both symmetric and asymmetric duopoly cases using a continuous‐time Markov chain (CTMC) model, we demonstrate that optimal IT security spending, expected firm profits and willingness of firms to cooperate on security improvements are highly dependent on the nature of customer response to adverse events. We also examine the investment problem when security attacks on different firms are correlated.     

Knowledge and the regulation of innovation

Technology assessment (TA) is an important instrument for the regulation of innovation. From the perspective of sociology of knowledge, the regulatory process can be understood as a complex interplay between different forms of knowledge. The prevailing instruments of TA, expertise and participation, are both facing difficulties in dealing with the limits and impasses of regulatory knowledge in the realm of innovation. Nevertheless, as is argued in this article, reflexive forms of TA offer a good, if not the only, answer to the question of how we can deal with the contradictions and paradoxes involved in the regulation of innovation.     

Divorces in Europe during the years 1950-1980

Data on legal divorces in more than 20 European countries are analyzed. A general trend toward higher rates of divorce is noted for the 1970s, although some countries showed declines in divorce during the 1950s, partly in contrast to the high rates observed immediately following World War II. Some explanations of recent divorce trends are attempted.     

Choosers as extension axioms

We consider the extension of a (strict) preference over a set to its power set. Elements of the power set are non-resolute outcomes. The final outcome is determined by an “(external) chooser” which is a resolute choice function. The individual whose preference is under consideration confronts a set of resolute choice functions which reflects the possible behaviors of the chooser. Every such set naturally induces an extension axiom (i.e., a rule that determines how an individual with a given preference over alternatives is required to rank certain sets). Our model allows to revisit various extension axioms of the literature. Interestingly, the Gärdenfors (1976) and Kelly (1977) principles are singled-out as the only two extension axioms compatible with the non-resolute outcome interpretation.