A Weighted Correlation Index for Rankings with Ties

Understanding the correlation between two different scores for the same set of items is a common problem in information retrieval, and the most commonly used statistics that quantifies this correlation is Kendall's $\tau$. However, the standard definition fails to capture that discordances between items with high rank are more important than those between items with low rank. Recently, a new measure of correlation based on average precision has been proposed to solve this problem, but like many alternative proposals in the literature it assumes that there are no ties in the scores. This is a major deficiency in a number of contexts, and in particular while comparing centrality scores on large graphs, as the obvious baseline, indegree, has a very large number of ties in web and social graphs. We propose to extend Kendall's definition in a natural way to take into account weights in the presence of ties. We prove a number of interesting mathematical properties of our generalization and describe an $O(n\log n)$ algorithm for its computation. We also validate the usefulness of our weighted measure of correlation using experimental data

Management of Acid Soils

Resource /Energy Economics and Policy,

Query Expansion with Locally-Trained Word Embeddings

Continuous space word embeddings have received a great deal of attention in the natural language processing and machine learning communities for their ability to model term similarity and other relationships. We study the use of term relatedness in the context of query expansion for ad hoc information retrieval. We demonstrate that word embeddings such as word2vec and GloVe, when trained globally, underperform corpus and query specific embeddings for retrieval tasks. These results suggest that other tasks benefiting from global embeddings may also benefit from local embeddings

Maintaining textuality: a case study of the problematic use of academic discourse conventions in the thesis text of an international graduate student

Supervising research students in the writing up of their theses may present special difficulties when these students do not come from an English speaking background (NESBs). Very often, the textual problems are attributed by both supervisors and students to “problems with English”. My purpose in presenting this representative case study is to show that 1) the major problems in the text examined are due to the student’s misapprehensions about and inadequate command of the institutionalized conventions of thesis writing; 2) these problems are crosscultural; 3) such phrases as “problems with English” are reductive in that they obscure full recognition and acknowledgment of the complexity of the writing culture students enter and its cultural constructedness; and 4) there is a need to decontextualize our language in communicating with NESBs about their texts if we are to help them master a very complex range of discourse conventions

This unfathomable thing called supervision: negotiating better working relationships with supervisors

Supervision has been a ‘hot’ topic on the postgraduate research agenda in recent years. This reflects the high importance of the supervisory relationship in completion of research theses and completion on tune, as well as the dissatisfaction sometimes voiced by students about their supervisory experiences. The varied and complex issues of postgraduate research supervision have now received considerable coverage in the literature (D. & K. Battersby, 1980; Powles, 1988 & 1994; Moses, 1984, 1988 &1990; Ballard & Clanchy, 1993; Parry & Hayden, 1994; Cullen et al, 1994; Acker et al ,1994). Special attention has been given to reviewing supervisors’ current practices and procedures, to improving practice, to initiating development workshops, training programs and so forth (Welsh, 1982; Christopherson et al, 1983; Connell, 1985; Ballard & Clanchy, 1991; Conrad, 1992; Moses, 1985 &1992; Nightingale, 1992; Powles, 1993; Russell, 1994; Whittle, 1994; Willcoxson, 1994). Expansive manuals detailing procedures for conducting residential workshop programs on postgraduate supervision, such as that edited by Zuber-Skerritt, have also appeared (1992). In short, there has been extensive scrutiny of the subject in the literature. The push behind the more ‘practical’ literature has been to increase the effectiveness of supervisors to supervise. Listening to conference participants detail the various initiatives they have introduced in their respective universities also reinforces my impression of focussed attention on the supervisor. It is important that this push to improve supervisory practice continues. It is also reasonable to ask what students themselves might be able to contribute to this two-way relationship. The question is though, whether students can take a more active role in determining what goes on in supervision, given the unequal power relations of which they are often acutely aware, particularly in the early stages of their degrees. Further questions are: if they can, why do so many seem not to? what might be the value for students generally in becoming more active on their own behalf? and what can be done to help them in this ? These questions have arisen from my advisory work with research students during the past five years. The questioning began, however, with submission of my own PhD and the realisation of how much time I had lost because of my own inefficiencies, often due to ignorance of a procedural kind. Since then, I have heard many completing PhDs express the same view. Only when it is all over do we become aware of how best to proceed, not only with the research and writing but also with a range of academic matters including handling supervision. There is not much comfort in knowing retrospectively. Some of this knowledge might be put to good use in future research projects, but most (there are a crazy few) will never again do a PhD

Contract Law, Default Rules, and the Philosophy of Promising

Among the topics addressed by moral philosophy is the obligation to keep one\u27s promises. To many philosophers, there is something strange (or, at least, something calling for explanatie1n) in the idea that moral obligations can be created simply by an individual\u27s saying so yet this is what seems to happen when a person makes a promise. Consequently, there is by now a large body of literature attempting to identify the exact source and nature of this moral obligation. Part I of this article presents a more detailed survey of recent philosophical writings about promises, for the benefit of legal readers who may be unfamiliar with that literature. Part II then discusses the role of background rules in contract law, and shows why the content of those rules cannot be derived from philosophical theories based on individual liberty, or on ideals such as fidelity or truthfulness. Finally, Part III examines the writings of Charles Fried and Randy Barnett to illustrate the consequences of attempting to apply philosophy to contract law without addressing these problems. These two authors have supplied the most comprehensive attempts to give contract law a philosophical grounding, yet each falls into exactly this error