Using natural language to access databases on the Web

As the traditional relational databases and the new XML document repositories are being widely used on the Web as information storage, there is a great need for easy access to the information sources, particularly through natural language interactions. In this paper, we present the design and implementation of an intelligent system that interacts with users using a natural language, English, and retrieves information from sources, for the users. The system consists of four major parts: part of speech tagging, query knowledge base, query formation, and answer synthesis. In implementation, the system first uses QTAG, a Hidden Markov Model based speech part tagger, to tag each word in the input sentence. Then, important words in the main phrase axe identified. A thesaurus is applied to reduce the important words to basic keywords, which are used to query the database. The query is formed based on the query knowledge stored in the query knowledge base. Finally, the query result is synthesized into an English sentence, which is presented to the user as the answer. With an efficient part of speech tagger, intelligent subsystems for query formation and synthesis of query result, and user-friendly interface, the intelligent system can answer questions effectively