Designing minimal effective normative systems with the help of lightweight formal methods

Normative systems (i.e., a set of rules) are an important approach to achieving effective coordination among (often an arbitrary number of) agents in multiagent systems. A normative system should be effective in ensuring the satisfaction of a desirable system property, and minimal (i.e., not containing norms that unnecessarily over-constrain the behaviors of agents). Designing or even automatically synthesizing minimal effective normative systems is highly non-trivial. Previous attempts on synthesizing such systems through simulations often fail to generate normative systems which are both minimal and effective. In this work, we propose a framework that facilitates designing of minimal effective normative systems using lightweight formal methods. Given a minimal effective normative system which coordinates many agents must be minimal and effective for a small number of agents, we start with automatically synthesizing one such system with a few agents. We then increase the number of agents so as to check whether the same design remains minimal and effective. If it is, we manually establish an induction proof so as to lift the design to an arbitrary number of agents

On the application of rainfall projections from a convection-permitting climate model to lumped catchment models

Climate change is predicted to increase rainfall intensity in tropical regions. Convection permitting (CP) climate models have been developed to address deficiencies in conventional climate models that use parameterised convection. However, to date, precipitation projections from CP climate models have not been used in conjunction with hydrological models to explore potential impacts of explicit modelling of convective rainfall on river flows in the tropics. Here we apply the outputs of a continental scale CP climate model as inputs to lumped rainfall-runoff models in Africa for the first time. Applied to five catchments in the Lake Victoria Basin, we show that the CP climate model produces greater river flows than an equivalent model using parameterised convection in both the current and future (c. 2100) climate. However, the location of the catchments near to Lake Victoria results in limited changes in extreme rainfall and river flows relative to changes in mean rainfall and river flows. Application of CP model rainfall data from an area where rainfall extremes change more than the change in mean rainfall to the rainfall-runoff model does not result in significant changes in river flows. Instead, this is shown to be a result of the rainfall-runoff model structure and parameterisation, which we posit is due to large-scale storage in the catchments associated with wetland cover, that buffers the impact of rainfall extremes. Based on an assessment of hydrological attributes (wetland coverage, water table depth, topography, precipitation, evapotranspiration and river flow) using global-scale datasets for the catchments in this research, this buffering may be extensive across humid regions. Application of CP climate model data to lumped catchment models in these areas are unlikely to result in significant increases in extreme river flows relative to increases in mean flows

Home bitter home? Gender, living arrangements, and the exclusion from homeownership among older Europeans

Abstract Homeownership is the most important asset among the elderly in Europe, but very little is known about gender and living arrangement differences in this domain. This paper aims at exploring patterns of exclusion from homeownership among middle-aged and older Europeans from a gender perspective, and with a special focus on their household composition. The analysis is based on the fourth wave of the “Survey of Health, Aging and Retirement in Europe” and includes a sub-sample of about 56,000 individuals aged 50 or over, living in 16 European countries. We estimated a set of multinomial logit models to examine the probability of being either tenant or rent-free occupiers versus homeowners. Our findings show that women are generally more likely to be excluded from homeownership than men. Nevertheless, a closer look suggests that the gender gap in homeownership is essentially generated by compositional differences between men and women, with the most relevant factor being household type. Older women are almost as twice as likely as men to live alone, which is associated—other things being equal—with a particular low likelihood to be homeowners virtually in every European country

The Necessity of Self-Employment Towards Retirement: Evidence from Labor Market Dynamics and Search Requirements for Unemployment Benefits

Hervorming Sociale Regelgevin