PC Repair Assistant
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First, let's specialize desk-top computers to x86-based desktop computers.
To further restrict the domain, the system diagnoses only hardware
problems, not software issues. Broken power supplies, loose video cards, and
faulty memory chips are typical of the class of problems that your program will
diagnose.
Finally, let's restrict the domain to include only computers that won't boot.
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* This is adapted from the example in chapter 12 "Writing the PC Repair Assistant" of the book "Jess In Action".