Different presentations of candidate expansion terms have not been fully explored in interactive query expansion (IQE). Most existing systems that offer an IQE facility use a list form of presentation. This paper examines an hierarchical presentation of the expansion terms which are automatically generated from a set of retrieved documents, organised in a general to specific manner, and visualised by cascade menus. To evaluate the effectiveness of the presentation, a user test was carried out to compare the hierarchical form with the conventional list form. This shows that users of the hierarchy can complete the expansion task in less time and with fewer terms over those using the lists. Relations between initial query terms and selected expansion terms were also investigated.

A medium-scale user study was carried out to investigate the usability of a concept-based query expansion support tool. The tool was fully integrated into the interface of an IR system, and designed to support the user by offering automatically generated concept hierarchies. Two types of hierarchies were compared with a baseline. Several observations were made as a result of the study: 1) the hierarchy is often accessed after an examination of the first page of search results; 2) accessing the hierarchies reduces the number of iterations and paging actions; 3) accessing the hierarchies increases the chance of finding relevant items more accurately than the baseline; 4) the hierarchical structure helps the users to handle a large number of concepts; and finally, 5) subjects were not aware of the difference between two types of hierarchies.

This paper discusses issues concerning the augmentation of thesaurus relationships, in light of new application possibilities for retrieval. We first discuss a case study that explored the retrieval potential of an augmented set of thesaurus relationships by specialising standard relationships into richer subtypes, in particular hierarchical geographical containment and the associative relationship. We then locate this work in a broader context by reviewing various attempts to build taxonomies of thesaurus relationships and conclude by discussing the feasibility of hierarchically augmenting the core set of thesaurus relationships, particularly the associative relationship. We discuss the possibility of enriching the specification and semantics of RT relationships, while maintaining compatibility with traditional thesauri via a limited hierarchical extension of the associative (and hierarchical) relationships. This would be facilitated by distinguishing the type of term from the (sub)type of relationship and explicitly specifying semantic categories for terms following a faceted approach. We first illustrate how hierarchical spatial relationships can be used to provide more flexible retrieval for queries incorporating place names in applications employing online gazetteers and geographical thesauri. We then employ a set of experimental scenarios to investigate key issues affecting use of the associative (RT) thesaurus relationships in semantic distance measures. Previous work has noted the potential of RTs in thesaurus search aids but also the problem of uncontrolled expansion of result sets. Results presented in this paper suggest a potential for taking account of the hierarchical context of an RT link and specialisations of the RT relationship. 1.

Hierarchies have long been used for organization, summarization, and access to information. In this dissertation we define summarization in terms of a probabilistic language model and use this definition to explore a new technique for automatically generating topic hierarchies. We use the language model to characterize the documents that will be summarized and then apply a graph-theoretic algorithm to determine the best topic words for the hierarchical summary. This work is very different from previous attempts to generate topic hierarchies because it relies on statistical analysis and language modeling to identify descriptive words for a document and organize the words in a hierarchical structure. We compare

Clear and precise queries are a necessity when searching very large document collections, especially when query-based retrieval is the only means of exploration. We propose system-mediated information access as a solution for users ’ well-documented inability to formulate good queries. Our approach is based on two main assumptions: first, on the ability of document clustering to reveal the topical, semantic structure of a problem domain represented by a specialized “source collection,” and, second, on the capacity of statistical language models to convey content. Taking the role of the human mediator or intermediary searcher, a mediation system interacts with the user and supports her exploration of a relatively small source collection, chosen to be representative for the problem domain. Based on the

The OASIS (Ontologically Augmented Spatial Information System) project explores terminology systems for thematic and spatial access in digital library applications. A prototype implementation uses data from the Royal Commission on the Ancient and Historical Monuments of Scotland, together with the Getty AAT and TGN thesauri. This paper describes its integrated spatial and thematic schema and discusses novel approaches to the application of thesauri in spatial and thematic semantic distance measures. Semantic distance measures can underpin interactive and automatic query expansion techniques by ranking lists of candidate terms. We first illustrate how hierarchical spatial relationships can be used to provide more flexible retrieval for queries incorporating place names in applications employing online gazetteers and geographical thesauri. We then employ a set of experimental scenarios to investigate key issues affecting use of the associative (RT) thesaurus relationships in semantic distance measures. Previous work has noted the potential of RTs in thesaurus search aids but the problem of increased noise in result sets has been emphasised. Specialising RTs allows the possibility of dynamically linking RT type to query context. Results presented in this paper demonstrate the potential for filtering on the context of the RT link and on subtypes of RT relationships.

Abstract: The author reports on a universal searchable index of Web resources for design