The study of semantic and ontological features of thesaurus and ontology based information retrieval systems

In order to increase in relevant retrieved results and users satisfaction achievement, Information retrieval systems, are seeking a way to change keyword-based search to concept-based search. These systems use the tools that can convert terms to concepts. Over the years, this provided the basis of tools production such as classification schema, vocabularies, subject headings and thesauri. Recently, ontologies use in Complementing of this process. The main problem of this research is that The Great information retrieval systems of the world that claim to use of ontologies and thesauri how use the semantic features of these tools in their information retrieval process. In this paper 7 information retrieval systems due use of these tools, were selected. The semantic features presented in form of research checklist with literature review. These features include 5 general categories concept search, synonyms search, suggestion for search, use of ontologies and display. The researcher examined these features with structured observation in form of checklist. Though these systems use these tools for searching and retrieving, but don`t show the expected features. In studied factors, ERIC database and national library of Australia achieved the maximum scores (32 and 24) and national archive of Australia and Britain museum had minimum scores (12 and 13).