A new semipartial geometry

Consider the graph INQ(2m, 3) on the internal points of a quadric Q(2m, 3), where vertices are adjacent when non-orthogonal. We prove that form odd and under the condition of existence of an orthogonal spread, the graph INQ(2m, 3),m 3, is the point graph of a new semipartial geometry SPQ(2m, 3).     

On (0,α)-Geometries and Dual Semipartial Geometries Fully Embedded in an Affine Space

The (0,α)-geometries fully embedded in a projective space are up to a few open cases classified. For (0,α)-geometries fully embedded in an affine space AG(n,q), less is known. The most important model is the so-called linear representation T _n-1* (k) of a set k of type {0,1,α +1} with respect to lines in the hyperplane at infinity. We will give a characterization of this model. We also investigate the case where the (0,α)-geometry, fully embedded in AG(n,q), is the dual of a semipartial geometry.     

Quality assurance and quality control in forest soil analyses: a comparison between European soil laboratories

In transnational monitoring programmes, a balance between international reference methods, which improve spatial comparability, and national analysis methods that favour temporal comparability, by their use and testing over many years, needs to be sought. Prior to the next Pan-European Forest Soil Survey, a third interlaboratory comparison of soil analysis methods was organised. All participating laboratories were requested to use the same reference methods. Fifty-two soil laboratories from 27 European countries analysed a total of 48 soil parameters on three soil samples which were typical for European forest soils. The results of the statistical analysis showed a high interlaboratory and intralaboratory variability, especially for the acid oxalate extractions, particle size distribution, exchangeable elements and total carbonates. The intercomparability of the test results did not improve compared to the previous ring test. As the exercise aimed primarily at comparing the performance of the laboratories, it was not powerful enough to find cause–effect relationships between the meta information provided by the laboratories and the variability of the test results.

     

Optimization of the annual planning of targeted offers in direct marketing

This paper develops an optimization model that captures the annual planning of product-targeting campaigns occurring in financial institutions. The formulation described in this paper extends current product-targeting optimization models found in the literature on two main aspects, namely the possibility of promoting bundled products and the use of multi-channel structures. The complexity of the problem is studied and extensive computational experiments are performed on representative data sets. The effect of client segmentation is empirically examined and some strategic applications of the model are presented. Our work is based on a practical case, but all features identifying the company have been removed.     

Partial geometries and the triality quadric

Up to now there are eight partial geometries pg(7,8,4) known. Their point graphs as well as their block graphs are all related to the triality quadric Q⁺(7,2). We prove that some of these graphs are the point graph of (up to isomorphism) exactly one partial geometry. We investigate the relations among some of these eight partial geometries. Generalizing our results, we construct two new families of partial geometries pg(2^2n–1– 1, 2^2n–1, 2^2n–2).The second author is a Research Fellow supported by the Flemish Institute for the Promotion of Scientific and Technological Research in Industry (IWT), grant No. IWT/SB/971002.     

Quality assurance and quality control in forest soil analyses: a comparison between European soil laboratories

In transnational monitoring programmes, a balance between international reference methods, which improve spatial comparability, and national analysis methods that favour temporal comparability, by their use and testing over many years, needs to be sought. Prior to the next Pan-European Forest Soil Survey, a third interlaboratory comparison of soil analysis methods was organised. All participating laboratories were requested to use the same reference methods. Fifty-two soil laboratories from 27 European countries analysed a total of 48 soil parameters on three soil samples which were typical for European forest soils. The results of the statistical analysis showed a high interlaboratory and intralaboratory variability, especially for the acid oxalate extractions, particle size distribution, exchangeable elements and total carbonates. The intercomparability of the test results did not improve compared to the previous ring test. As the exercise aimed primarily at comparing the performance of the laboratories, it was not powerful enough to find cause–effect relationships between the meta information provided by the laboratories and the variability of the test results.     

Two-Weight Codes, Partial Geometries and Steiner Systems

Two-weight codes and projectivesets having two intersection sizes with hyperplanes are equivalentobjects and they define strongly regular graphs. We construct projective sets in PG(2m – 1,q) that have the sameintersection numbers with hyperplanes as the hyperbolic quadricQ⁺(2m – 1,q). We investigate these sets; we provethat if q = 2 the corresponding strongly regular graphsare switching equivalent and that they contain subconstituentsthat are point graphs of partial geometries. If m = 4the partial geometries have parameters s = 7, t = 8, = 4 and some of them are embeddable in Steinersystems S(2,8,120).