Information filtering systems are designed for unstructured or semistructured data, as opposed to database applications, which use very structured data. The systems also deal primarily with textual information, but they may also entail images, voice, video or other data types that are part of multimedia information systems. Information filtering systems also involve a large amount of data and streams of incoming data, whether broadcast from a remote source or sent directly by other sources. Filtering is based on descriptions of individual or group information preferences, or profiles, that typically represent long-term interests. Filtering also implies removal of data from an incoming stream rather than finding data in the stream; users see only the data that is extracted. Models of information retrieval and filtering, and lessons for filtering from retrieval research are presented.

this document, text or image about?' Gradually moving from the left to the right in Figure 3.1, different understandings of this concept evolve

This study investigates the use and effectiveness of an advanced information retrieval (IR) system (IN-QUERY). 64 novice IR system users were studied in their use of a baseline version of INQUERY compared with one of three experimental versions, each offering a different level of interaction with a relevance feedback facility for automatic query reformulation. Results, in an information filtering task, indicate that: these subjects, after minimal training, were able to use the baseline system reasonably effectively; availability and use of automatic relevance feedback increased retrieval effectiveness significantly; and increased opportunity for user interaction with and control of relevance feedback made the interactions more efficient and usable while maintaining or increasing effectiveness.

Lexical ambiguity is a pervasive problem in natural language processing. However, little quantitative information is available about the extent of the problem, or about the impact that it has on information retrieval systems. We report on an analysis of lexical ambiguity in information retrieval test collections, and on experiments to determine the utility of word meanings for separating relevant from non-relevant documents. The experiments show that there is considerable ambiguity even in a specialized database. Word senses

The objective of the paper is to amalgamate theories of text retrieval from various research traditions into a cognitive theory for information retrieval interaction. Set in a cognitive framework, the paper outlines the concept of polyrepresentation applied to both the user's cognitive space and the information space of IR systems. The concept seeks to represent the current user's information need, problem state, and domain work task or interest in a structure of causality. Further, it implies that we should apply different methods of representation and a variety of IR techniques of different cognitive and functional origin simultaneously to each semantic full-text entity in the information space. The cognitive differences imply that by applying cognitive overlaps of information objects, originating from different interpretations of such objects through time and by type, the degree of uncertainty inherent in IR is decreased. Polyrepresentation and the use of cognitive overlaps are associated with, but not identical to, data

Statistically based ranked retrieval of records using keywords provides many advantages over traditional Boolean retrieval methods, especially for end users. This approach to retrieval, however, has not seen wide-spread use in large operational retrieval systems. To show the feasibility of this retrieval methodology, re-search was done to produce very fast search tech-niques using these ranking algorithms, and then to test the results against large databases with many end users. The results show not only response times on the order of 1 and l/2 seconds for 806 megabytes of text, but also very favorable user reaction. Novice users were able to consistently obtain good search results after 5 minutes of training. Additional work was done to de-vise new indexing techniques to create inverted files for large databases using a minicomputer. These techniques use no sorting, require a working space of only about 20 % of the size of the input text, and produce indices that are about 14 % of the input text size.

The focus of this article is to develop a map display for to stack in the dark, without knowing what stacks that information retrieval. Through an examination of relationships among visual displays, information retrieval, and browsing, advantages of visual displays for informa-tion retrieval are characterized as (1) the ability to con-we have walked through. We can get a few books each time and walk out of the library to see if the book we are searching for is among them. If not, we have to walk vey a large amount of information in a limited space, (2) in again, based on our knowledge and our previous experi-the potential to reveal semantic relationships of terms ence, to a location where we hope the book would be. In and documents, and (3) the facilitation of browsing and perceptual inferences on retrieval interfaces. These ad-vantages are further demonstrated through a map dis-play generated by a neural network’s self-organizing al-this situation, success in finding a book greatly depends on whether we can walk to the right place in the dark (to generate a good query), and whether we know how to gorithm. The map display detects complex relationships adjust our locations until we get to the right place (to among given documents, and reveals the relationships modify queries interactively). through a spatial arrangement of terms abstracted from Can we turn on the light for such a library? Can we the documents. The map display also provides inter-active tools to allow the user to interact with the underlydevelop some visible cues in our retrieval systems so that ing information. Examples of the map displays show that we can use our perception for information seeking in such map displays can be used both as an overview tool the digital environment? Answers to these questions may and an access or exploration tool, and the map displays will likely increase the amount of information that the user is willing to browse. reside in the recent advance of information technology. ‘‘Information processing has been evolving from numeri-cal computation to character handling, and now to visual information processing’ ’ (Kunii, 1989). As a result, visu-

. As the amount of electronic information increases, traditional lexical (or Boolean) information retrieval techniques will become less useful. Large, heterogeneous collections will be difficult to search since the sheer volume of unranked documents returned in response to a query will overwhelm the user. Vector-space approaches to information retrieval, on the other hand, allow the user to search for concepts rather than specific words and rank the results of the search according to their relative similarity to the query. One vector-space approach, Latent Semantic Indexing (LSI), has achieved up to 30% better retrieval performance than lexical searching techniques by employing a reduced-rank model of the term-document space. However, the original implementation of LSI lacked the execution efficiency required to make LSI useful for large data sets. A new implementation of LSI, LSI++, seeks to make LSI efficient, extensible, portable, and maintainable. The LSI++ Application Programming ...

Improved data management is crucial to the success of current scientific investigations of Global Change. New modes of research, especially the synergistic interactions between observations and model-based simulations, will require massive amounts of diverse data to be stored, organized, accessed, distributed, visualized, and analyzed. Achieving the goals of the U.S. Global Change Research Program will largely depend on more advanced data management systems that will allow scientists to manipulate large-scale data sets and climate system models. Refinements in computing --- specifically involving storage, networking, distributed file systems, extensible distributed data base management, and visualization --- can be applied to a range of Global Change applications through a series of specific investigation scenarios. Computer scientists and environmental researchers at several UC campuses will collaborate to address these challenges. This project complements both NASA's EOS project and ...

This article outlines an approach that avoids these problems by choosing a retrieval method that utilizes minimal repository structure to effectively support the process of finding software components. The approach is demonstrated through a pair of proof-ofconcept prototypes: PEEL, a tool to semiautomatically identify reusable components, and CodeFinder, a retrieval system that compensates for the lack of explicit knowledge structures through a spreading activation retrieval process. CodeFinder also allows component representations to be modified while users are searching for information. This mechanism adapts to the changing nature of the information in the repository and incrementally improves the repository while people use it. The combination of these techniques holds potential for designing software repositories that minimize up-front costs, effectively support the search process, and evolve with an organization's changing needs.