Study Of Semantic Query Expansion Based On Ontology

With the fast development of Internet in recent years, Web resources increase at an explosive speed. The Internet is exploding with plenty of resources, but it is hard to find what we want. In the process of using search engines, one major problem is term mismatch between queries and documents. Traditional information retrieval technologies can not meet the needs for better organizations, understanding and processing services in the semantic level.In the Chinese information retrieval, because the terminology used in the query may be mismatch to the terminology used in the document, so some relevant documents can not be successfully crawled out. It is the key issue that impact the search results. Query expansion can solve the mismatch of the terminology to a certain extent, on the basis study of above in this paper, in view of the current query expansion technology of information system, we present semantic query expansion based on ontology and study on it. In the query expansion stage, use's query keywords according to the area ontology, after a group of reasoning operation, achieve synonyms expansion, context expansion and same level expansion, form rich expansion of concept, then submitted to search. The main contributions are as follows:1 .This paper analyzes the effectiveness of several categories of query expansion using term expansion or term re-weighted.2.This paper builds an area ontology to ensure that users can search the semantic retrieval smoothly and properly describes the relevant area knowledge. In this paper we build a sports ontology to experiment. This paper also builds corresponding concept hierarchy of ontology and concept-connected graph with weight.3.An ontology-based query method is proposed. We analyze the limitation of the traditional query expansion methods on dealing with semantic, and present three semantic patterns of user query and relevant methods to expand the ontology concepts and properties into user queries, which is different from the normal ontology-based expansion. The method uses different techniques, such as concept-connected graph and concept hierarchy of ontology, to expand different parts in query.4.The experiment uses the source code of the Lucene Project, and achieves the semantic query expansion module on the project. The experiment verifies the validity of the ontology-based expansion.