Re: Storing data and code in a Db with LISP-like interface

"Neo" <neo55592_at_hotmail.com> wrote in message news:1145746437.660905.240120_at_g10g2000cwb.googlegroups.com...

>
> Ok, I see. Suppose we start with the following:
>
> subtype(doctor, human).
> subtype(engineer, human).
> named_instance(john, doctor).
> named_instance(mary, doctor).
>
> And now comes along an alien named bob, who has all the major
> characteristics of a doctor, but he is not a human. How do I handle
> this situation?
>

If this is true, then an alien can be a doctor and Bob can be an alien. Therefore, we can no longer say, for certain, that 'just because john is a doctor, therefore he is human,' because there are now alien doctors. The ruleset change is small.

subtype(doctor, alien).
subtype(doctor, human).
subtype(engineer, human).
named_instance(john, doctor).

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