ABSTRACT
Natural languages are the primary mode of human communication. In their textual form they constitute the most widely used medium for storing human knowledge. Natural languages are also the most expressive knowledge representation languages that exist, far more expressive than any machine-processable formal language. While natural languages allow humans to deal with most aspects of everyday life, their expressive power can create problems for both humans and machines. Sometimes it is difficult for humans who have only limited knowledge of an official language that is used in a work environment to read and understand technical documents. It is also often difficult for machines to process full natural language for a given task because of its inherent ambiguity and complexity.
