This paper reports on City University's work on the TREC{2 project from its commencement up to November 1993. It includes many results which were obtained after the August 1993 deadline for submission of o cial results. For TREC{2, as for TREC{1, City University used versions of the Okapi text retrieval system much as described in [2] (see also [3, 4]). Okapi is a simple and robust set-oriented...

Okapi (Okapia johnstoni) are an even-toed ungulate in the family Giraffidae, and are endemic to the Democratic Republic of Congo (DRC). Very little is known about okapi ecology in the wild. We used non-invasive genetic methods to examine the social structure, mating system and dispersal for a population of okapi in the Réserve de Faune à Okapis, DRC. Okapi individuals appear to be solitary, alt...

The BSS, which has been used in all City's TREC experiments, is a set-oriented ranked output system designed primarily for probabilistic{type retrieval of textual material using inverted indexes. There is a family of built-in weighting functions as described in [1, Section 3]. In addition to weighting and ranking facilities it has the usual boolean and quasi-boolean (positional) operations. The...

Purpose – Being an important data exchange and information storage standard, XML has generated a great deal of interest and particular attention has been paid to the issue of XML indexing. Clear use cases for structured search in XML have been established. However, most of the research in the area is either based on relational database systems or specialized semi-structured data management syst...

Motivated by the hypothesis that the retrieval performance of a weighting model is independent of the language in which queries and collection are expressed, we compared the retrieval performance of three weighting models, i.e., Okapi, statistical language modeling (SLM), and deviation from randomness (DFR), on three monolingual test collections, i.e., French, Italian, and Spanish. The DFR mode...

During the course of TREC{1 the low-level search functions were split o into a separate Basic Search System (BSS) [2], but retrieval and ranking of documents was still done using the \classical" probabilistic model of Robertson and Sparck Jones[7] with no account taken of document length or term frequency within document or query. Four runs were submitted to NIST for evaluation: automatic ad ho...

City submitted two runs each for the automatic ad hoc, very large collection track, automatic routing and Chinese track; and took part in the interactive and ltering tracks. There were no very signi cant new developments; the same Okapi-style weighting as in TREC{3 and TREC{4 was used this time round, although there were attempts, in the ad hoc and more notably in the Chinese experiments, to ex...

In this brief communication, we evaluate the use of two stopword lists for the English language (one comprising 571 words and another with 9) and compare them with a search approach accounting for all word forms. We show that through implementing the original Okapi form or certain ones derived from the Divergence from Randomness (DFR) paradigm, significantly lower performance levelsmay result w...