A spanning heuristic for the unordered and ordered matching identification problem

The matching identification problem (MIP) is a combinatoric search problem related to the fields of learning from examples, boolean functions, and knowledge acquisition. The MIP involves identifying a single “goal” item from a large set of items. Because there is commonly a cost associated with evaluating each guess, the goal item should be identified in as few guesses as possible. As in most search problems, the items have a similar structure, which allows an evaluation of each guessed item. In other words, each guessed item elicits partial information about the goal item, i.e. how similar the guess is to the goal. With this information the goal is more quickly identified.The unordered MIP has been studied by Mehrez and Steinberg (ORSA J. Comput. 7 (1995) 211) in which they proposed two different types of algorithms. The purpose of the present paper is to suggest an improved Spanning Heuristic algorithm. Its improvement increases as the problem size increases. Further results and comparisons are derived for the unordered and ordered cases.This research shows that when the search space is very large, it is better to inquire from items that are known not to be the goal (they have been ruled out by previous guesses), for the purpose of acquiring more information about the goal. As the search space is narrowed, it is better to guess items that have not been ruled out.     

Soziologische Theorie,Handlungstheorie, Methoden,Familiensoziologie, Sozialstrukturanalyse,Raumsoziologie, Stadtsoziologie,Gedächtnissoziologie,Religionssoziologie

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Soziologische Theorie, Handlungstheorie, Methoden, Familiensoziologie, Sozialstrukturanalyse, Raumsoziologie, Stadtsoziologie, Ged?chtnissoziologie, Religionssoziologie     

A characterization of linearizable instances of the quadratic minimum spanning tree problem

We investigate special cases of the quadratic minimum spanning tree problem (QMSTP) on a graph \(G=(V,E)\) that can be solved as a linear minimum spanning tree problem. We give a characterization of such problems when G is a complete graph, which is the standard case in the QMSTP literature. We extend our characterization to a larger class of graphs that include complete bipartite graphs and cactuses, among others. Our characterization can be verified in \(O(|E|^2)\) time. In the case of complete graphs and when the cost matrix is given in factored form, we show that our characterization can be verified in O(|E|) time. Related open problems are also indicated.     

Global Robustness with Respect to the Loss Function and the Prior

We propose a class [I,S] of loss functions for modeling the imprecise preferences of the decision maker in Bayesian Decision Theory. This class is built upon two extreme loss functions I and S which reflect the limited information about the loss function. We give an approximation of the set of Bayes actions for every loss function in [I,S] and every prior in a mixture class; if the decision space is a subset of , we obtain the exact set.     

Improved estimators for the selected location parameters

_i , i = 1, 2, ..., k be k independent exponential populations with different unknown location parameters θ _i , i = 1, 2, ..., k and common known scale parameter σ. Let Y _i denote the smallest observation based on a random sample of size n from the i-th population. Suppose a subset of the given k population is selected using the subset selection procedure according to which the population π _i is selected iff Y _i ≥Y ₍₁₎−d, where Y ₍₁₎ is the largest of the Y _i 's and d is some suitable constant. The estimation of the location parameters associated with the selected populations is considered for the squared error loss. It is observed that the natural estimator dominates the unbiased estimator. It is also shown that the natural estimator itself is inadmissible and a class of improved estimators that dominate the natural estimator is obtained. The improved estimators are consistent and their risks are shown to be O(kn ⁻²). As a special case, we obtain the coresponding results for the estimation of θ₍₁₎, the parameter associated with Y ₍₁₎. Received: January 6, 1998; revised version: July 11, 2000     

Renyi's entropy for residual lifetime distribution

In the present paper, we introduce and study Renyi's information measure (entropy) for residual lifetime distributions. It is shown that the proposed measure uniquely determines the distribution. We present characterizations for some lifetime models. Further, we define two new classes of life distributions based on this measure. Various properties of these classes are also given.     

Microdata Access and Labor Market Research: The U. S. Experience

Summary: The paper illustrates the value of broad researcher access to survey and administrative microdata using examples drawn from the U. S. experience, outlining how analyses of trends in earnings inequality, poverty and employment dynamics using such data have benefited policy makers and contributed to improvements in statistical agency data products. Methods of facilitating researcher access, including the release of public use files, the use of licensing agreements, and the establishment of research data centers, are discussed. * The author thanks Anne Polivka, Marilyn Seastrom and two anonymous referees for helpful comments on an earlier draft of the paper.     

Who participates,who does not,and why? An analysis of voluntary neighborhood organizations in the United States and Israel

Lack of participation in voluntary associations and the associated issues of why people do or do not participate are major areas of interest in the research literature concerning citizen participation. The present study used three types of variables (demographic, social psychological, and costs/benefits) to investigate the characteristics of participants and nonparticipants in neighborhood-type organizations in the United States and Israel. Findings from analysis of the demographic variables show some cross-cultural similarities (including a surprising lack of race/ethnic and education differences between participants and nonparticipants). There were striking cross-cultural similarities using the social psychological variables. The data from the Israel sample provide important information on the costs and benefits of participation. A discriminant analysis points to the predictive strength of social psychological and cost/benefit variables in comparison to demographic variables. Implications of these results for explanatory and predictive purposes are discussed.