Basic aspects of evolution strategies

Evolution strategies (ESs) are a special class of probabilistic, direct, global optimization methods. They are similar to genetic algorithms but work in continuous spaces and have the additional capability of self-adapting their major strategy parameters. This paper presents the most important features of ESs, namely their self-adaptation, as well as their robustness and potential for parallelization which they share with other evolutionary algorithms.Besides the early (1 + 1)-ES and its underlying theoretical results, the modern ( + )-ES and (, )-ES are presented with special emphasis on the self-adaptation of strategy parameters, a mechanism which enables the algorithm to evolve not only the object variables but also the characteristics of the probability distributions of normally distributed mutations. The self-adaptation property of the algorithm is also illustrated by an experimental example.The robustness of ESs is demonstrated for noisy fitness evaluations and by its application to discrete optimization problems, namely the travelling salesman problem (TSP).Finally, the paper concludes by summarizing existing work and general possibilities regarding the parallelization of evolution strategies and evolutionary algorithms in general.     

Sampling from spatial databases

This paper deals with techniques for obtaining random point samples from spatial databases. We seek random points from a continuous domain (usually ²) which satisfy a spatial predicate that is represented in the database as a collection of polygons. Several applications of spatial sampling (e.g. environmental monitoring, agronomy, forestry, etc) are described. Sampling problems are characterized in terms of two key parameters: coverage (selectivity), and expected stabbing number (overlap). We discuss two fundamental approaches to sampling with spatial predicates, depending on whether we sample first or evaluate the predicate first. The approaches are described in the context of both quadtrees and R-trees, detailing the sample first, acceptance/rejection tree, and partial area tree algorithms. A sequential algorithm, the one-pass spatial reservoir algorithm is also described. The relative performance of the various sampling algorithms is compared and choice of preferred algorithms is suggested. We conclude with a short discussion of possible extensions.     

Waste paper and the market mechanism

Increasing attention is being given to the possible consequences which might follow from the exhaustion of the world's natural resources. Countering the pessimistic conclusions of such institutions as the Club of Rome, economists such as Wilfred Beckerman have emphasized the importance of substitution, pointing to many examples where a shortage of one raw material has led to the discovery or development of alternative materials, e.g. artificial for natural rubber, aluminium for copper.Substitution usually occurs through normal market mechanisms, i.e. changes in relative prices. However in some circumstances the market mechanism may be inhibited by a variety of factors, so that its operation requires to be supplemented by an outside agency. This article explores this possibility in relation to the paper making industry, which provides a particularly interesting example owing to the existence of a well established market in waste paper, the main substitute for the major natural resource, woodpulp.A brief indication is given of the relative importance of waste paper and an outline of the structure of the U.K. market; the conditions under which greater utilization of waste paper might occur are then considered taking a sideways look at the influence of the individual. In the final section the various implications for the role of the state are summarized.     

Political Competence and Mass Media Use

Relationships are examined between feelings of political competenceand cumulative media usage in five Western nations. Wide differentiationamong the nations studied is found, suggesting that multivariateanalysis is needed to establish whether media usage makes aunique contribution to feelings of political competence, oracts as a surrogate for other background variables.     

Managerial Involvement and Perceptions of Strategy Process

Prior academic research attests to both positive and negative effects of involvement on the process of developing strategy. On the one hand, it has been argued that involvement strengthens shared vision, increases rationality and improves adaptiveness in strategy-making. On the other hand, involvement is said to lead to intense political behaviour, increased cultural inertia and more constraints in the strategy process. The purpose of this study is to investigate the relative importance of these effects. In a survey of over 6,000 managers, we find that their reported levels of involvement are positively associated with perceptions of strategy development processes that are more rational, more focused by a shared vision, and more adaptive. In addition, involvement is negatively associated with statements describing the process as top-down, influenced by politics and slowed by internal culture. Moreover, those who are more involved tend to see business and non-business constraints as less important in determining strategy. We argue that these associations between involvement and desirable features of strategy process are important because perceptions are the basis of managerial behaviour. Thus, managers who are more involved in strategy not only see the process in a more favourable light but also act in ways that make the process more effective. The main implication of these findings is that for most organisations increasing involvement improves the strategy process.     

The Blinders of Dominant Logic

This article argues that the dominant logic embedded in an organisation may keep it on the road ahead, but it also acts as a blinder to peripheral vision. It says that managers need to look at beyond the borders of their industries and geographies to find new opportunities and rethink the logic of the business. It refers to corporate examples where shifts in organisations’ dominant logic allowed traditional assumptions about value creation to be reassessed and resulted in successful forays into the periphery.     

Mining the Periphery for New Products

Revolutionary products often come from upstart players or companies outside the industry, while mainstream operators follow a risk-averse path of concentrating on their current business. This article urges companies to channel resources into looking at the periphery for ideas that could be profit-drivers of the future. It suggests three strategies for finding new products: frame the landscape; develop game-changing hypotheses; and use targeted hunting. It concludes by saying that these approaches will encourage managers to combine broad searching and thinking with focused evaluation and execution.     

Beyond Planning:: Strategies for Successfully Implementing Strategic Decisions

This article brings strategy back to managers and their organizations. It argues and demonstrates empirically that what managers do, and the kind of organization they lead, matter in terms of achieving stated objectives. Managerial action involves a set of activities from assessing the problem to prioritising action, and takes place within an organizational context which has two important elements for decision-making. First, organizations have an accumulated stock of experience, and the more managers can access and utilise this experience base the better. Secondly, the culture and structure of an organization may exhibit more or less readiness for the changes that decisions bring about, and contexts less ready for change pose problems for managers in the implementation of decisions.This long-term study of 55 decisions in UK firms shows that careful managerial planning does not of itself guarantee successful outcomes: the organizational context is crucial in framing actions and influencing achievement, and decisions may send a firm on a trajectory beyond the point at which it can plan with confidence. Where experience and readiness are strong, decisions achieve stated objectives—where both are lacking, decisions tend to fail. But, as examination of two illustrative cases indicates, strength in either domain may be enough: sound experience may win out in comparatively unreceptive situations, and decisions may still succeed where experience is lacking but the organization is ready for change. The article closes with some implications for managers.     

Social Loafing: A Field Investigation

Social loafing was investigated by testing a multilevel model among 23 intact work groups comprised of 168 employees representing two organizations. Results demonstrated that as hypothesized at the individual level, increases in task interdependence and decreases in task visibility and distributive justice were associated with greater occurrence of social loafing. At the group level, increased group size and decreased cohesiveness were related to increased levels of social loafing. Of particular interest was the finding that group member perceptions of perceived coworker loafing was associated with reduced social loafing, opposite of our predictions. We suggested that this unexpected finding may provide evidence of a social compensation effect.