Abstract. The theory of concept (or Galois) lattices provides a simple and formal approach to conceptual clustering. In this paper we present GALOIS, a system that automates and applies this theory. The algorithm utilized by GALOIS to build a concept lattice is incremental and efficient, each update being done in time at most quadratic in the number of objects in the lattice. Also, the algorithm may incorporate background information into the lattice, and through clustering, extend the scope of the theory. The application we present is concerned with information retrieval via browsing, for which we argue that concept lattices may represent major support structures. We describe a prototype user interface for browsing through the concept lattice of a document-term relation, possibly enriched with a thesaurus of terms. An experimental evaluation of the system performed on a medium-sized bibliographic database shows good retrieval performance and a significant improvement after the introduction of background knowledge.

A controlled experiment was conducted comparing information retrieval using a Galois lattice structure with two more conventional retrieval methods: navigating in a manually built hierarchical classification and Boolean querying with index terms. No significant performance difference was found between Boolean querying and the Galois lattice retrieval method for subject searching with the three measures used for the experiment: user searching time, recall and precision. However, hierarchical classification retrieval did show significantly lower recall compared to the two other methods. This experiment suggests that retrieval using a Galois lattice structure may be an attractive alternative since it combines a good performance for subject searching along with browsing potential. 11/12/98 2 1. Introduction Information retrieval is concerned with the representation, storage, organization, and accessing of information items (Salton & McGill, 1983). As opposed to the traditional f...

In this paper we generalize the two level approach approach to hypertext (hypermedia) systems into stratified hypermedia structures. First we describe the overall architecture of such systems, including the fundamentals of the user interface. Thereafter, its various components are discussed. Special emphasis is paid to how the underlying information model is layered. Two layers are featured: the hyperbase and the hyperindex. A characterization calculus is presented for the characterization of structured elements. This calculus forms the basis of a logic-based approach in connection with the associated information processor (Disclosure Machine). The logic-based approach is considered as the most general approach to the retrieval process. In addition, this calculus is useful for quality assurance in hypermedia applications. Attention is also paid to spatial coherence for relevance judgements. 1 This work has been partially supported by the ESPRIT project APPED (2499). 1 1...

: In this article the formal basis of hyperindices is given. Hyperindices are a new means for supporting effective search in hypermedia. The basis of the hyperindex, the so called index expression is treated in detail. It is shown how the hyperindex can be constructed using the structural properties of the index expression. The hyperindex is placed in a general framework for indexes which features quantitative and qualitative criteria with which index effectiveness can be judged. KEY WORDS : hypertext, information retrieval, indexing. Published as: P.D. Bruza. Hyperindices: A Novel Aid for Searching in Hypermedia. In A. Rizk, N. Streitz, and J. Andre, editors, Proceedings of the European Conference on Hypertext - ECHT 90, pages 109--122, Cambridge, United Kingdom, 1990. Cambridge University Press. 1 Introduction People wishing to retrieve information are sometimes confronted with a problem at the beginning of their search. It may be that they do not have a clear idea of their informat...

. Specification-based retrieval provides exact content-oriented access to component libraries but requires too much deductive power. Specification-based browsing evades this bottleneck by moving any deduction into an off-line indexing phase. In this paper, we show how match relations are used to build an appropriate index and how formal concept analysis is used to build a suitable navigation structure. This structure has the single-focus property (i.e., any sensible subset of a library is represented by a single node) and supports attribute-based (via explicit component properties) and object-based (via implicit component similarities) navigation styles. It thus combines the exact semantics of formal methods with the interactive navigation possibilities of informal methods. Experiments show that current theorem provers can solve enough of the emerging proof problems to make browsing feasible. The navigation structure also indicates situations where additional abstractions are required ...

In this article we present the Two Level Hypermedia architecture. Both levels of this architecture are detailed in the framework of a conceptual model of hypermedia. A central aspect of this model is the notion of a view. The concept of a hyperindex is introduced, which is a novel approach to organizing indexing information relevant for hypermedia. In conjunction with the hyperindex, the notion of Query by Navigation (QBN) is introduced. 1 Introduction Hypermedia is becoming more and more popular as a structure that enables user-friendly access to large amounts of information. The term hypermedia is used in order to stress the fact that data types other than text may be involved. Hypertext refers to text-only hypermedia. a This work has been partially supported by the ESPRIT project APPED (2499). 1 There are however some problems. One of the most important problems is what is usually referred to as being lost in hyperspace [SK89]. This problem can be introduced by the analogy of ...

Often queries to internet search engines consist of one or two terms. As a consequence, the effectiveness of the retrieval suffers. This paper describes an internet search engine that helps the user formulate their query by a process of navigation through a structured, automatically constructed, information space called a hyperindex. In the first part of this paper, the logs of an internet search engine were analyzed to determine the proportions with which different types of query transformation occur. It was found that the primary transformation type was repetition of the previous query. Users also substitute, add and delete terms from a previous query and with lower frequency split compound terms, make changes to spelling, punctuation, and case and use derivative forms of words and abbreviations. The second part of the paper details the hyperindex - which aids the user in query term addition and deletion. The architecture of a hyperindex-based internet search engine is presented. Som...

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Query formulation in the context of large conceptual schemata is known to be a hard problem. When formulating ad-hoc queries users may become overwhelmed by the vast amount of information that is stored in the information system; leading to a feeling of lost in conceptual space. In this article we develop a strategy to cope with this problem. This strategy is based on ideas from the information retrieval world. In particular the query by navigation mechanism and the stratified hypermedia architecture. The stratified hypermedia architecture is used to describe the information contained in the information system on multiple levels of abstraction. When using our approach to the formulation of queries, a user will first formulate a number of simple queries corresponding to linear paths through the information structure. The formulation of the linear paths is the result of the explorative phase of query formulation. Once users have specified a number of these linear paths, they ma...

The recent advances in Formal Concept Analysis (FCA) together with the major changes faced by modern Information Retrieval (IR) provide new unprecedented challenges and opportunities for FCA-based IR applications. The main advantage of FCA for IR is the possibility of creating a conceptual representation of a given document collection in the form of a document lattice, which may be used both to improve the retrieval of specific items and to drive the mining of the collection’s contents. In this paper, we will examine the best features of FCA for solving IR tasks that could not be easily addressed by conventional systems, as well as the most critical aspects for building FCA-based IR applications. These observations have led to the development of CREDO, a system that allows the user to query Web documents and see retrieval results organized in a browsable concept lattice. This is the second major focus of the paper. We will show that CREDO is especially useful for quickly locating the documents corresponding to the meaning of interest among those retrieved in response to an ambiguous query, or for mining the contents of the documents that reference a given entity. An on-line version of the system is available for testing at