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VP-Expert offers high-end expert-system-shell features for a low-end price. Version 3.0, now a WordTech Systems software product (Paperback Software previously owned VP-Expert), introduces some refinements, but VP-Expert hasn't changed much in the past three years. Some of the old weaknesses we noticed in our last review still remain.
Still, for automatically creating simple expert systems and being able to edit them into more sophisticated applications, hardly a better product exists than VP-Expert.
We used the scoring criteria from our June 19, 1989, product comparison of expert system shells. Our test bed was a 25-MHz 386DX running DOS 5.0, with 4 megabytes of RAM, a VGA monitor, and 80-megabyte hard drive.
FEATURES
VP-Expert lets you quickly throw together an expert system. You can create a knowledge base in two basic ways: You can write your own rules (English if/then statements that have conditions and conclusions) in VP-Expert's editor (a version of Paperback Software's word processor).
Or, you can import a text table, database file, or a spreadsheet and have VP-Expert's inference engine automatically induce the rules for you into a basic expert system. In any case, you can always further edit the rules and refine them into a more sophisticated knowledge base. For instance, you may want to rewrite some of the prompts for clarity: You might want the system to ask "What is your income?" instead of "What is the value of income?"
VP-Expert now supports not only "and" but other operators such as "greater than" and "or." Programming is done in a simple, English-like language. VP-Expert also uses extended memory. You can create an unlimited number of knowledge bases, and you can recursively chain up to 20.
As you become more familiar with the program, you can use variables so that as your databases of information change, VP-Expert can update its knowledge base; it can "learn" about new situations so you don't have to constantly revamp the program manually. For instance, an expert system for a real estate business will need to be able to accommodate a continuous influx of new information about homes on the market.
VP-Expert comes with a collection of dynamic images that lets you add modifiable graphical objects to your system. These objects let you add hypertext capability, gauges...