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Building Expert Systems using PCPLUS from TI

The Agricultural Engineering department has developed several expert system applications using Texas Instruments' Personal Consultant Plus Development Tools on PCs. PCPLUS is a set of integrated software utilities that allow developers to effectively capture and utilize expert knowledge. With Personal Consultant Plus, you can solve large difficult problems yet still take advantage of the affordable environment of today's advanced personal computers.

Expert systems are software programs that help you solve complex reasoning tasks that normally require an expert. This type of software offers:

• High performance in specialized areas (or domains)
• High degree of flexibility
• Emphasis on knowledge processing
• Natural dialogue interaction with users

PC+ is a rule-based expert system which consists of a knowledge base and an inference engine.

The knowledge base contains information, consisting of facts and rules, about a specific domain. A domain is a particular area or sphere of interest or activity that an expert system addresses.

Rules describe the logical relationships among elements of information within the domain.

The inference engine is the program that processes the rules and information and makes inferences (judgments) to arrive at specific conclusions.

Personal Consultant Plus is designed for developers who:

• Want to develop sophisticated commercial expert system applications for delivery on personal computers
• Need to quickly prototype an initial concept or problem solution
• Are technically proficient in microcomputers and computer languages
• Want to provide an easy-to-use application
• Need flexibility to solve a broad range of problems

Personal Consultant Plus uses an interactive menu and window oriented interface for building and running knowledge bases. This interface allows you to build knowledge bases by answering prompts for the operations you want to perform. After the knowledge base is built, the client uses similar menus and windows to run the expert system. This menu and window combination makes it easy to work with Personal Consultant Plus.

Personal Consultant Plus also offers powerful control structures for knowledge engineers who want more sophisticated control in their expert systems. Such advanced features are:

• Meta-rules....For controlling rules.
• Access methods....For triggering actions, such as reading instruments or updating displays.
• User-defined functions....For accessing data from an external source, printing graphics, or other uses. You can program any high-level Lisp functions and add them to your knowledge base as user-defined functions.

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