A deductive data model for query expansion

Abstract

We present a deductive data model for conceptbased query expansion. It ]s based on three abstraction levels: the conceptual, linguistic and occurrence levels. Concepts and relationships among them are represented at the conceptual level. The expression level represents natural language expressions for concepts. Each expression has one or more matchmg models at the occurrence level. The models specify the matching of the expression in database Indices built in varying ways. The data model supports a concept-based query expansion and formulation tool, the ExpansionTool, for heterogeneous IR system envirom ments, Expansion is controlled by adjustable matching reliability.

On the efficient evaluation of relaxed queries in biological databases

“…Then, the relaxation can be done bottom-up along the tree structures. This is similar to the methods proposed in [KJ98,JKN96]. For the second kind of similarities, a new concept of the socalled fuzzy equivalence classes is developed to capture the relationships among residue types.…”

“…In [YK98], a sort of query relaxation is carried out by loosening the searching condition in the sense of database theory. In [KJ98, JKN96], queries are expanded in terms of thesauri, by which narrower partitive concepts can be replaced with hierarchically broader generic concepts. A third kind of query expansion is based on an interactive approach, by which users select the terms of interests from a list to add to the initial queries [MSB98,Co00,Ef00].…”

User evaluation of ontology as query construction tool

“…stems, lemmatised or inflected forms of the words (Järvelin et al 1996(Järvelin et al , 2001). An example of the abstraction levels is given in Fig.…”

“…At linguistic level, terms and all synonyms of any expression denoting the original or expansion concepts are collected. Then, at occurrence level, matching models of terms and their synonyms are placed into the query, (Järvelin et al, 1996;Kekäläinen, 1999). The number of hierarchical expansion levels can be changed, but the default was used in the test.…”

“…Although there are different kinds of ontologies, they all can be described as specifications of a conceptualisation, or models showing concepts and their relations (Guarino, 1995). The ontology of the study is based on three abstraction levels: It includes concepts, expressions representing concepts, and matching models representing expressions as search keys (Järvelin et al 1996). Semantic relations typical of thesauri are also represented in the ontology.…”