Elimination of Source A and B Errors in p-Median Location Problems

The p-median problem is a powerful tool in analyzing facility location options when the goal of the location scheme is to minimize the average distance that demand must traverse to reach its nearest facility. It may be used to determine the number of facilities to site, as well as the actual facility locations. Demand data are frequently aggregated in p-median location problems to reduce the computational complexity of the problem. Demand data aggregation, however, results in the loss of locational information. This loss may lead to suboptimal facility location configurations (optimality errors) and inaccurate measures of the resulting travel distances (cost errors). Hillsman and Rhoda (1978) have identified three error components: Source A, B, and C errors, which may result from demand data aggregation. In this article, a method to measure weighted travel distances in p-median problems which eliminates Source A and B errors is proposed. Test problem results indicate that the proposed measurement scheme yields solutions with lower optimality and cost errors than does the traditional distance measurement scheme.     

Recursive Algorithm for Determination of Proximal (Thiessen) Polygons in Any Metric Space

A new and recursive algorithm for determining proximal polygons is based on quadtree concepts. The algorithm can use any distance metric, and produces a quadtree of the image of the proximal polygons. This can be converted to vector form, or be incorporated directly into a quadtree-based geographic information system, in order to solve a number of closest-point problems. The algorithm can also produce the Delaunay triangulation, which is the dual of the proximal polygons. Empirically, the running time of the algorithm is proportional to the number of centers raised to the 1.6 power.     

Reviews of books

Historical Archaeology -     

JEWISH AND MORMON AGRICULTURAL SETTLEMENT IN WESTERN CANADA: A COMPARATIVE ANALYSIS

Mormons and Jews established agricultural settlements in western Canada around the turn of the century. Mormon colonization was generally successful, characterized by its great stability. Abandonment of the land by Mormon communities was rare. In contrast, almost all the Jewish settlements failed. Settlers abandoned their land and retreated to the urban centres of the West. A comparative analysis of the two groups suggests that this difference in agricultural stability may not have been a reflection of prior experience, nor was it necessarily attributable to vagaries of the physical environment. Social structures, religious demands, and institutional backing, along with the geographical concentration and inter connectivity of settlements were critical elements in determining success or failure in agriculture colonization.
C'est au début du siècle que les Mormons et les juifs etablirent dans l'Ouest canadien leurs colonies agricoles. La colonisation des Mormons, caractérisée par sa grande stabilite, réussit dans l'ensemble; rares furent les colonies qu'ils abandonnèrent. Par contre, presque toutes les colonies juives echouerent; abandonnant leurs terres, les colons se retirerent dans les centres urbains de l'Ouest. Une analyse comparative des deux groupes permet de conchre que leur stabilite agricole relative ne fut pas necessairement fonction de leur experience prealable en agriculture; elle ne fut pas non plus attribuable aux seules contraintes géographiques et clirnatiques.
Les structures sociales, les exigences religieuses, l'appui de leurs établissements en plus de la proximité d'autres colonies et leurs interrelations, tous ces facteurs s'avérèrent cruciaux pour déterminer la reussite ou l'échec de la colonisation agricole.     

Illicit Drug Production and Supply-side Drugs Policy in Asia and South America

This paper examines the feasibility of current policies of supply limitation as an instrument for the control of dangerous drugs (principally South American cocaine and Asian heroin). The structure of production and distribution is examined, and revenue estimates are made. A range of supply-side policy options are evaluated by means of a simple game-theory approach. In all cases, it is concluded that supply-side policies are likely to prove ineffectual as a means of drug control.