Research On Ontology-Based Knowledge Representation And Information Retrieval

With the rapid growth of network information,the traditional information retrieval based on keywords technology has gradually can't satisfy people's needs.And knowledge retrieval emphasizing knowledge and semantic matching, with high precision and recall, became the research hotspot of the fileds of artificial intelligence and information retrieval.Ontology's good concept hierarchical structure is suitable for knowledge representation. Ontology can fully describe domain knowledge model,reflecting the semantic relations between concepts and supporting logical inference. So the knowledge retrieval based on ontology can be better implementing semantic retrieval and improve retrieval accuracy.Based on analysis and comparison of the knowledge representation of ontology, ontology description language, editing tools and modeling method,this thesis presented the computer science and technology domain ontology building process,which ordinal achieved computer domain ontology's knowledge expression elements:concepts, inheritance relationships, attribute relations, instances and so on, and the algorithm and technologies involved were analyzed and implemented for each step.Firstly,a second development based on ICTCLAS open source system, implemented pretreatment of the corpus including word segmentation and removing stop words.Secondly,the feature words were extrcated from computer filed corpus by weight calculation algorithm method TF-IDF,thus they made up computer science filed's candidate concepts.Then through the calculation method of degree of correlation,builded concept of vector model, and used cosine formula to compute the concept similarity,after artificially clustering, the computer domain knowledge inheritance relationship hierarchical structure was obtained.Finally based on concept inheritance relationship, obtained object attribute between concepts, data attribute of concepts and restrictions. After obtained the above domain ontology knowledge representation elements,using protege builded computer domain ontology and evaluated it.Based on computer domain ontology, this thesis studied the key technologies of information retrieval based on ontology.First analysised and compared retrieval characteristics of data retrieval,fulltext retrieval and knowledge retrieval technology, and this thesis indicated that the advantages of knowledge retrieval based on ontology.Secondly on the basis of general reasoning rules and typical relationship reasoning rules, builded a series of field computer domain ontology reasoning rules,supporting reasoning functions of knowledge retrieval system.Finally, this thesis proposed a heuristic inquires extended algorithm and processes based on ontology, to ensure the recall rate of information retrieval. Finally on the basis of theory technical research and computer domain ontology, designed and implemented a paper retrieval system. The system provided conditions retrieval and navigation retrieval the two retrieval methods. It has functions of good semantic reasoning and query expansion, also verified the correctness of the theory and technology.