It is concerned with the concepts and methods of symbolic inference, or reasoning, by a computer, and how the knowledge used to make those inferences will be represented inside the machine. Often, the term expert systems is reserved for programs whose knowledge base contains the knowledge used by human experts, in contrast to knowledge gathered from textbooks or non-experts. Taken together, they represent the most widespread type of AI application. The area of human intellectual endeavor to be captured in an expert system is called the task domain . Domain refers to the area within which the task is being performed.
Typical tasks are diagnosis, planning, scheduling, configuration and design.
An example of a task domain is aircraft crew scheduling, discussed in Chapter 2 . Building an expert system is known as knowledge engineering and its practitioners are called knowledge engineers . The knowledge engineer must make sure that the computer has all the knowledge needed to solve a problem. He must also ensure that the computer can use the knowledge efficiently by selecting from a handful of reasoning methods . The practice of knowledge engineering is described later.