(30th-June-2020)
• Typically, you know more about a domain than a database of facts; you know general rules from which other facts can be derived. Which facts are explicitly given and which are derived is a choice to be made when designing and building a knowledge base.
• Primitive knowledge is knowledge that is defined explicitly by facts. Derived knowledge is knowledge that can be inferred from other knowledge. Derived knowledge is usually specified in terms of rules.
• The use of rules allows for a more compact representation of knowledge. Derived relations allow for conclusions to be drawn from observations of the domain. This is important because you do not directly observe everything about a domain. Much of what is known about a domain is inferred from the observations and more general knowledge.
• A standard way to use derived knowledge is to put individuals into classes. We give general properties to classes so that individuals inherit the properties of classes. The reason we group individuals into classes is because the members of a class have attributes in common, or they have common properties that make sense for them (see the box).
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