Abstract-Semantic Web promises to add metadata to web content to make it understandable to computers. Search is the most widely used activity on web. Semantic search engines have already changed the way we search the data on web. Uren. V, Yuanguilei Uren et al., proposed requirement space pyramid arguing that iterative and exploratory search modes are important to the usability of search engines. It identified the types of semantic queries the users need to make, the issues concerning the search development and the problems intrinsic to semantic search in particular. We have extensively examined the semantic search engines and have done broad survey to analyse the semantic search engines. Comparative analysis of the semantic search engines have been done on the basis of factors cited in the pyramid. The research provides deep understanding of five main semantic search engines based on comparative analysis that may help for future work for semantic web in general and for semantic search engines in particular.Index Terms-Semantic web, semantic search engine, requirement space pyramid.
I. INTRODUCTIONSemantic Web [1], the future of web, promises to provide content that will be understandable to computer. Search is the most important and popular applications of the web. Semantic search [2] is one of the most significant applications of semantic web. Recently a number of semantic search engines have been introduced. Semantic Search engine is a tool that produces precise results to user queries by retrieving data semantically [3]. The purpose of this paper is to compare semantic search engines along with their salient characteristic approaches. This paper focuses mainly on five semantic search engines including Hakia, Sensebot, Powerset, Lexxe and Cognition. There are many benchmarks and standards used in every field and computer science is not an exception. Google and other search engines have revolutionized the world with their services but with the idea of semantic search, the rise of semantic search engines has changed the requirements and issues related with search engines. A pyramid scheme has been used as model for discussion to present the requirements, issues and challenges for semantic search engines. The remaining paper has been formatted as follows that related work have discussed in section II. Comparative evaluation of the semantic search engines on the basis of the pyramid has been described in Manuscript received November 8, 2012; revised January 28, 2013 section III. The semantic search engines along with their GUI's have been discussed in section IV while finally the concluding remarks include the issues and challenges of semantic search engines.
II. RELATED WORKSSemantic search engine is new field and realtively less work has been done in this domain. Hakia has been compared with google, yahoo and msn in [4] and that of Hakia with dogpile. A relation-based page rank algorithm has been proposed to be used as semantic web search engine. In this work, relevance is measured as probability of finding con...