Knowledge Representation and Question Answering

Consider an intelligence analyst who has a large body of documents of various kinds. He would like answers to some of his questions based on the information in these documents, general knowledge available in compilations such as fact books, and commonsense. A search engine or a typical information retrieval (IR) system like Google does not go far enough as it takes keywords and only gives a ranked list of documents which may contain those keywords. Often this list is very long and the analyst still has to read the documents in the list. Other reasons behind the unsuitability of an IR system (for an analyst) are that the nuances of a question in a natural language can not be adequately expressed through keywords, most IR systems ignore synonyms, and most IR systems cannot reason. What the intelligence analyst would like is a system that can take the documents and the analyst's question as input, that can access the data in fact books, and that can do commonsense reasoning based on them to provide answers to questions. Such a system is referred to as a question answering system or a QA system. Systems of this type are useful in many domains besides intelligence analysis. Examples include a Biologist who needs answers to his questions, say about a particular set of genes and what is known about their functions and interactions, based on the published literature; a lawyer looking for answers from a body of past law cases; and a patent attorney looking for answers from a patent database. A precursor to question answering is database querying where one queries a database using a database query language. Question Answering takes this to a whole other dimension where the system has increasing body of documents (in natural languages, possibly including multimedia objects and possibly situated in the web and described in a web language) and it is asked a query in natural language. It is expected to give an answer to the question, not only using the documents, but also using appropriate commonsense knowl