(An) information retrieval model based on a hybrid knowledge-base

Abstract

From a couple of years ago, extensive research efforts have been devoted to the knowledge-based approach to information retrieval. These are usually based on thesauri that admit a variety of relations between control vocabularies called index terms. However, there have been few systems to offer sufficient functions enough to deal with domain dependent knowledge as well as domain independent one in storing and retrieving information. Accordingly, it is extremely difficult for an information seeker to get the documents relevant to his query without the aid of a domain expert or librarian. This thesis aims at developing a knowledge-based information retrieval system that is easy for a naive user to use allowing to retrieve relevant documents effectively, without help. For this, it proposes a knowledge-based model that lets most of heuristics be represented in a simple and structured manner. As the knowledge is usually categorized by domain independent and domain dependent one, it separates the store of the knowledge into two boxes: domain independent knowledge Box (Ibox) and domain dependent knowledge Box (Dbox). Ibox is used as a graph-based thesaurus that permits "is-a" relation between index terms. Dbox describes domain-specific information, such as synonym relationship, some term relationships other than "is-a" relation, generation rules for complex compound phrases, and some heuristics for navigating Ibox. A Dbox is used as the front-end to Ibox that helps to convert the arbitrary terminology given by an IR user to the index terms implied in Ibox, and reflects domain dependent knowledge. According to this, a system named HYKIS (Hybrid Knowledge-based Information retrieval System) is developed. In HYKIS, the query evaluation procedure, QEP retrieves the documents relevant to a query given as Boolean form, interacting with Ibox and Dbox. It first retrieves all related documents and takes the ones of highest rank by Rada``s algorithm. We show that Rada``s algori...