Why "is-a" is not an instance of "instance-of"? Confused?

Copyright © 2002 Robert Barta

The Topic Map standard contains two predefined association types, class-instance and superclass-subclass which should be used in a consistent manner to build a proper type system (taxonomy) for any authored map. This short article suggests a best current practice using these association types to allow merging and reasoning by a Topic Map processor.

1. Why is not an instance of ? Confused?