PPT Slide
Since development of these abstractions is the first thing we do when
developing a software system, we should be careful to derive
the best possible set of abstractions for our purpose. How
will we know when we have a good set of abstractions? (An
abstraction is itself an entity so can be described in terms
of attributes and behaviors.)
Abstraction is an iterative process. We apply abstraction
(and composition) to obtain a domain definition. We then
evaluate the abstractions by these criteria and iterate until