Cambridge O Level Computer Science · Syllabus 2210 · Automated and Emerging Technologies
Knowledge Base
What is Knowledge Base?
The component of an expert system that stores the facts and domain-specific expert knowledge about one narrow subject area, gathered from human experts.
This definition is part of the Automated and Emerging Technologies chapter in Cambridge O Level Computer Science.
Knowledge Base in context
An expert system is an AI system that reproduces the decision-making of a human expert within one narrow domain. The syllabus specifies exactly four components: a knowledge base, a rule base, an inference engine and an interface. The knowledge base stores facts about the domain; the rule base stores the rules that say what follows from those facts; the inference engine applies the rules to the information supplied and reasons towards a conclusion; and the interface is how the user and the system communicate. Learn all four names and one sentence for each — the syllabus names exactly these four.
Common mistakes with Knowledge Base
- M18. “AI output is always correct, and always unbiased.” Why wrong An expert system is limited by its knowledge, its rules and what the user typed. A machine-learning model reproduces whatever is in its training data, including its errors and its bias. Say instead “The conclusion is a recommendation for a person to check, and its quality depends on the completeness of the knowledge base and the accuracy of the answers supplied.”
- M20. “The knowledge base and the rule base are the same component — and the inference engine stores the knowledge.” Why wrong Three separate components are being merged. The knowledge base holds facts; the rule base holds the rules that draw conclusions from facts; the inference engine holds neither — it is the reasoning process that consults both. Say instead “The inference engine searches the rule base for rules whose conditions the supplied facts satisfy, and applies them using knowledge from the knowledge base.”
Questions students ask about Knowledge Base
What is the difference between the knowledge base and the rule base?
The knowledge base holds the facts and expert knowledge about the domain — what is true. The rule base holds the rules, commonly written as IF … THEN, that say what conclusion follows from a combination of facts — what may be concluded. They are listed separately in the syllabus, so merging them in an answer cannot earn both marks.