 This is a small example on how to create a classification expert-system in
 TURBO-Prolog.

 Animals are classified in different categories which are further
 specified. One can come from one category to another if a number of
 conditions are fulfilled.

 Please understand this is an example not a finished expert system
 development tool.

 Note:  At the prompt to update, enter a ? and an example will be
        shown.

        "NOT" is a predicate.  The condition "not is a fast car" will
        fail if "is a fast car" has been asserted into the database.

