Question answering system: A survey

Question answering (QA) is new research domain in the field of Information Science comes into focus in last few decades. Question answering systems are pretty much different from web based search engines which works on the principal of Information Retrieval (IR), however QA systems works on the concept of Information Retrieval (IR) as well as Information Extraction (IE). Web based search engines takes user´s query in natural language and responds the same with references and URLs of related documents and websites, but they failed when a user wants precise answer for their query. By considering these limitations of search engines people finds that there is a need for such a system which answer the user´s query rather responds with references or URLs of related documents. User should be provided with the precise answer to their question. They are one step ahead of web search engines which provides relevant documents against users query however QA system provides precise answer. A QA system comprises of three core components question classification, information retrieval and answer extraction module. Answer extraction module distinguishes QA system from web search engines. Question classification module plays an important role in QA since it identifies the type of information user have asked for. Similarly information retrieval is also important, because if none of the retrieved document contains answer sets no further processing can be done.