Artificial Intelligence

Natural language is human language. Natural-language-processing programs use artificial intelligence to allow a user to communicate with a computer in the user's natural language. The computer can both understand and respond to commands given in a natural language.

Computer languages are artificial languages, invented for the sake of communicating instructions to computers and enabling them to communicate with each other. Most computer languages consist of a combination of symbols, numbers, and some words. These languages are complex and may take years to master. By programming computers (via computer languages) to respond to our natural languages, we make them easier to use.

However, there are many problems in trying to make a computer understand people. Four problems arise that can cause misunderstanding: (1) Ambiguity—confusion over what is meant due to multiple meanings of words and phrases. (2) Imprecision—thoughts are sometimes expressed in vague and inexact terms. (3) Incompleteness—the entire idea is not presented, and the listener is expected to "read between the lines." (4) Inaccuracy—spelling, punctuation, and grammar problems can obscure meaning. When we speak to one another, furthermore, we generally expect to be understood because our common language assumes all the meanings that we share as members of a specific cultural group. To a nonnative speaker, who shares fewer of our cultural background, our meaning may not always be clear. It is even more difficult for computers, which have no share at all in the real-world relationships that confer meaning upon information, to correctly interpret natural language.

To alleviate these problems, natural language processing programs seek to analyze syntax—the way words are put together in a sentence or phrase; semantics—the derived meaning of the phrase or sentence; and context—the meaning of distinct words within a sentence. But even this is not enough. The computer must also have access to a dictionary which contains definitions of every word and phrase it is likely to encounter, and may also use keyword analysis—a pattern-matching technique in which the program scans the text, looking for words that it has been programmed to recognize. If a keyword is found, the program responds by manipulating the text to form a reasonable response.

In its simplest form, a natural language processing program works like this: a sentence is typed in on the keyboard; if the program can derive meaning—that is, if it has a reference in its knowledge base for every word and phrase—it will respond, more or less appropriately. An example of a computer with a natural language processor is the computerized card catalog available in many public libraries. The main menu usually offers four choices for looking up information: search by author, search by title, search by subject, or search by keyword. If you want a list of books on a specific topic or subject you type in the appropriate phrase. You are asking the computer—in English—to tell you what is available on the topic. The computer usually responds in a very short time—in English—with a list of books along with call numbers so you can find what you need.