Page "Knowledge representation and reasoning" Paragraph 67

Using frames for expert systems is an application of object-oriented programming, with inheritance of features described by the " is-a " link.

However, there has been no small amount of inconsistency in the usage of the " is-a " link: Ronald J. Brachman wrote a paper titled " What IS-A is and isn't ", wherein 29 different semantics were found in projects whose knowledge representation schemes involved an " is-a " link.

Other links include the " part-of " link.