Content area
Full text
One of the clearest definitions of an expert system was written by Kenneth Quinn in 1990. He defined an expert system as
an interactive computer program that asks the same questions a human expert would ask, and from the information given to it by the user, provides the same answer the expert would provide.(1)
He goes on to say, that if a body of knowledge can be codified into a set of questions and answers, it can be incorporated into an expert system software program.
Conceptually, expert systems are a branch of artificial intelligence (AI). AI itself is the area of computer science that is concerned with making computers smarter. More specifically, AI is a collection of software techniques that enable a computer to emulate functions of the brain. Dan W. Patterson defined AI as a discipline that is concerned with the study and creation of computer systems that exhibit some form of intelligence. He defines intelligence as:
a system that can learn new concepts and tasks; reason and draw useful conclusions about the world around us; understand a natural language; and perceive and comprehend a visual scene.(2)
In order to implement AI, special programming languages have been developed, such as Prolog and LISP. In "conventional" programming languages such as Pascal, C, COBOL, or BASIC, programs are written that tell the computer specifically what to do and how to do it. The computer is given a step-by-step sequence called an algorithm that clearly defines the actions that must be taken to solve a problem. The programmer decides what the inputs are and what the desired outputs should be.
Using Prolog or Lisp on the other hand,(3) we can represent relationships between concepts and design programs that search declared facts and rules to confirm or deny a hypothesis. In Prolog or Lisp a knowledge base representing the domain (or area under study) is represented symbolically. A symbol can be words, letters, or numbers that can be used to represent objects, actions, and their relationships. These objects or actions can represent anything, including real-world concepts such as people, places, events, and ideas -- such as the concept "main entry." Various facts are stated about the objects, actions, and processes and how all of them are interrelated....