Ontology Based Semantic Search: An Introduction and a Survey of Current Approaches A. Sudha Ramkumar, Dr. B. Poorna Research Scholar, Bharathiar University , Principal, SSS Jain College, Coimbatore, India. Chennai, India. sudharam99@gmail.com poornasundar@yahoo.com Abstract --Ontology based semantic search will lead to new generation of search based on the meaning of keyword rather than keyword and helps in finding correct information on the web. Here, ontology provides an explicit specification of conceptualization which helps to connect the information on the existing web pages with the background knowledge. Ontology based search overcomes the semantic gap between the keyword found in documents and those in query. This survey provides an introduction to ontology based semantic search and review the different details of selected ontology based search approaches and compare them by means of classification criteria. Based on this comparison, this survey attempts to identify the possible directions for future research. Keywords: ontology; semantic search; classification criteria. I. INTRODUCTION The Semantic Web aims to extend the current web standards and technology so that the semantics of the web is machine processible[1]. The use of ontology in the search process provides an interaction between machine and human. Traditional search process is based on term based searches, retrieving resources conceptually related to the user informational need. Queries will be expressed in several ways, and will be mapped on the semantic level defining topics that must be retrieved from the web. Recently, a number of ontology based search have been published. Their application area and their realization are different. However, they are based on a common set of ideas. This survey attempts to identify the ideas and introduces classification criteria for better understanding of these approaches. Although the ontology based semantic search has been used in current scenario, still there is a need for a survey of this field because there are a number of open issues need to be solved. This survey discusses about different approaches that makes use of the domain ontology to process search request. Use of domain ontology enables to define concepts and relations representing knowledge of a particular domain. The ontology based semantic search makes the search engine more intelligent by adding meaning and structure to the web pages and query. Terminology Traditional search depends on the occurrence of the keywords in document. Ontology based semantic search has been defined to be an information retrieval process that uses the background knowledge of the domain ontology. Domain ontology is a hierarchically structured set of terms to describe a domain that can be used as a skeletal foundation for a knowledge base [2]. For the rest of the paper concept is used to denote the terms. The word individual represents instances or facts and property represents the relationship or slots. The goal of ontology based semantic search is to maximize precision and recall where Precision = Number of relevant documents Retrieved Number of documents retrieved Recall = Number of documents retrieved Number of relevant documents F-Measure = Precision * Recall Precision + Recall The rest of the paper is organized as follows. Section II introduces 6 criteria that are used to classify the ontology based semantic search approaches. Section III summarises selected search approaches for ontology based search. Section IV compares the selected approaches from section III along with the criteria introduced in section II. Section V identifies issues for further development and research. Finally, Section VI concludes the paper. II. CLASSIFICATION CRITERIA This section presents classification criteria that are useful to categorize different approaches for ontology based search along several directions. The following classification criteria which captures important characteristics of search process: ontology technology, semantic annotation, Indexing, Ranking, Information retrieval model, and performance improvements. There are other criteria to classify search process are also exists, however they have not been discussed in this survey. The set of criteria do not taken into consideration for this survey is diverse and includes, e.g., ontology construction, ontology navigation, inferencing. Section IV discusses about the classification criteria and compares them to identify semantically efficient factors. Ontology Technology Ontology technologies are popular and attract much attention because they’re cornerstone for realizing the Semantic Web [24]. Ontology technologies includes inference engine, annotation tools, ontology based crawlers 2014 International Conference on Intelligent Computing Applications 978-1-4799-3966-4/14 $31.00 © 2014 IEEE DOI 10.1109/ICICA.2014.82 372