Implementation of Standard Genetic Algorithm on MIMD machines

Genetic Algorithms (GAs) have been implemented on a number of multiprocessor machines. In many cases the GA has been adapted to the hardware structure of the system. This paper describes the implementation of a standard genetic algorithm on several MIMD multiprocessor systems. It discusses the data dependencies of the different parts of the algorithm and the changes necessary to adapt the serial version to the parallel versions. Timing measurements and speedups are given for a common problem implemented on all machines

“Till the muddle in my mind have cleared awa”: can we help shape policy using systems modelling?

This paper considers how some well-documented deficiencies of mental models make it difficult to create effective policies, and suggests that systems modelling can begin to address this issue. To illustrate the argument three short cases are presented. These relate to specific domains but demonstrate how systems modelling can illuminate different general phenomena: effects on labour costs (unintended consequences and feedback); fishery management (accumulation and non-linearity) and child protection (worldviews and sense-making). Six levers for increasing the use of systems modelling in the policy arena are then discussed. The paper closes by emphasising the opportunities for systems modellers in the Anthropocene Era

The Galois approach to uniform structures

Entourages in uniform spaces, being binary relations, may be easily described by polarities (i.e. Galois connections between power sets) and axialities (i.e. residuated pairs between power sets). Here we consider this in the pointfree context of the category of frames, establishing characterizations of uniformities in terms of either the quantale of Galois connections or the quantale of residuated pairs. In virtue of this we conclude that frame uniformities may be thought of as either a family of polarities or as a family of axialities. The latter is precisely Fletcher-Hunsaker's approach to frame uniformities, showing that Galois connections rather than entourages are at the root of this approach. Then we prove that the equivalence between the somewhat different approaches to uniform frames of Fletcher-Hunsaker and Picado is a consequence of a very general phenomenon on Galois connections. Besides, we present a categorical description for the composition of Galois connections that justifies its definition.Quaestiones Mathematicae 28(2005), 355–373