A quadratic lower bound for Rocchio’s similarity-based relevance feedback algorithm with a fixed query updating factor

Rocchio’s similarity-based relevance feedback algorithm, one of the most important query reformation methods in information retrieval, is essentially an adaptive supervised learning algorithm from examples. In practice, Rocchio’s algorithm often uses a fixed query updating factor. When this is the case, we strengthen the linear Ω(n) lower bound obtained by Chen and Zhu (Inf. Retr. 5:61–86, 2002) and prove that Rocchio’s algorithm makes Ω(k(n−k)) mistakes in searching for a collection of documents represented by a monotone disjunction of k relevant features over the n-dimensional binary vector space {0,1} ⁿ , when the inner product similarity measure is used. A quadratic lower bound is obtained when k is linearly proportional to n. We also prove an O(k(n−k)³) upper bound for Rocchio’s algorithm with the inner product similarity measure in searching for such a collection of documents with a constant query updating factor and a zero classification threshold.     

A Caution on Comparisons

Abstract

The family is the foundation of our society. By learning about family life in other countries, we learn about our own lives and we realize that we all belong to one big family—the family of mankind. … [Studying families of the world] could help us to get closer to people in distant countries and support the knowledge that “we are one.” — Liv Ullmann, UNICEF Goodwill Ambassador     

The Long Goodbye: Women, Companion Animals, and Maternal Loss

Heightened and often anxious attachment to companion animals can be one of the sequela of women's unresolved grief over early maternal loss. Clinical data suggest that, especially among women, the death of pets can reactivate the unfinished mourning over the mother. Drawing on one extensive case study, this paper examines this little explored, but commonly experienced relationship. From the perspectives of attachment theory and feminist therapy, the paper addresses the human-animal bond, gender differences in grief, the long term effects of early maternal loss, later attachment style, and companion animals as internalized parent/child figures. Recommendations for treatment are offered to help women work through both losses.     

Nonresponse in the American Time Use Survey: Who Is Missing from the Data and How Much Does It Matter?

This article examines nonresponse in a large government survey,the American Time Use Survey (ATUS), which interviews personsin households previously interviewed in the Current PopulationSurvey. The response rate for the ATUS has been below 60 percentfor the first two years of its existence, raising questionsabout whether the results can be generalized to the target population.The article begins with an analysis of the types of nonresponseencountered in the ATUS. Noncontact accounts for roughly 60percent of ATUS nonresponse, with refusals accounting for roughly40 percent. We find little support for the hypothesis that busypeople are less likely to respond to the ATUS but find considerablesupport for the hypothesis that people who are weakly integratedinto their communities are less likely to respond, mostly becausethey are less likely to be contacted. When we compare aggregateestimates of time use calculated using the ATUS base weightswithout any adjustment for nonresponse, estimates calculatedusing the ATUS final weights with a nonresponse adjustment,and estimates calculated using weights that incorporate ourown nonresponse adjustment based on a propensity model, we findsome modest differences, but the three sets of estimates arebroadly similar. The article ends with suggestions for furtherresearch and analysis.     

Leader–member exchange,feelings of energy,and involvement in creative work

This study examined how leaders create the impetus for creativity at work. One hundred ninety-three employees occupying a variety of jobs in Israeli organizations completed surveys at two points in time to assess their perceptions of the quality of their relationship with their leader (LMX), their level of energy, and their creative work involvement. SEM and regression analyses showed that LMX was positively related to employees' feelings of energy, which in turn were related to a high level of involvement in creative work. Factors that leaders should take into consideration in promoting followers' creative behaviors are discussed.     

Estimation in Epidemics with Incomplete Observations

The construction of estimating equations by martingale methods is generalized to yield estimators with explicit expressions for the parameters of the birth-and-death and the general epidemic processes when only partial observations are available. (For the birth-and-death process the death process is observed but the number of births is observed only at the end and for the general epidemic process only the removal process is observed.) For large populations, the use of the martingale central limit theorem yields asymptotic confidence regions for the parameters. Explicit expressions are derived for estimators of the variances of the large sample distributions. The range of validity and usefulness of the new estimators is determined by simulation.     

‘Germany Has Become Mohammedan’: Insurgency,Long-Distance Travel,and the Singapore Mutiny, 1915

Abstract

The mutiny that took place in Singapore in February 1915 is usually dismissed as a footnote in the history of empire. One reason why it is marginalized is because the mutiny does not conform to a politics that seeks the formation of an independent territorial nation-state as its inevitable conclusion. This article returns to that initial moment of insurgency to argue that the mutiny offers a unique window into the political imaginaries of British Indian soldiers, seen as military migrant workers. A close reading of soldiers’ letters against the Rowlatt Committee's Sedition Report suggests a politics of equality and emancipation uncontaminated by the desire for national liberation. Two kinds of insurgency thus become visible: international space as an unsettled zone of attraction and desire and a nascent political subjectivity that rejects the disciplines of imperial military labor. The primary causes of these transformations, I argue, are the insurgent effects of long-distance travel.     

Unsupervised Curve Clustering using B-Splines

Data in many different fields come to practitioners through a process naturally described as functional. Although data are gathered as finite vector and may contain measurement errors, the functional form have to be taken into account. We propose a clustering procedure of such data emphasizing the functional nature of the objects. The new clustering method consists of two stages: fitting the functional data by B‐splines and partitioning the estimated model coefficients using a k‐means algorithm. Strong consistency of the clustering method is proved and a real‐world example from food industry is given.