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From: bobd@zaphod.UUCP (Bob Dalgleish)
Newsgroups: net.lang.prolog
Subject: Re: "assert" considered harmful?
Message-ID: <561@zaphod.UUCP>
Date: Fri, 20-Jun-86 18:09:16 EDT
Article-I.D.: zaphod.561
Posted: Fri Jun 20 18:09:16 1986
Date-Received: Sun, 22-Jun-86 07:17:48 EDT
References: <1754@utai.UUCP> <269@ubc-cs.UUCP> <1245@lsuc.UUCP>
Reply-To: bobd@zaphod.UUCP (Bob Dalgleish)
Organization: Develcon Electronics, Saskatoon SK Canada
Lines: 26
Keywords: cache optimization production

In the suggested application, this is the way that I would use assert:

controls(T1, T2) :- known_controls(T1, T2).
controls(T1, T2) :- figure_out_controlling_interests(T1,T2),
		    assert(known_controls(T1,T2)).

You now have a "program" portion (controls), and a data caching portion
(known_controls) which are separated.  Certainly, we need to separate
the two issues of program purity (required to support compilation), and
academic purity (required to support ivory towers).

Tax-planning is a very good application for an expert system, and using
standard computational science methods to make the implementation viable
is in all of our best interests.

Adding time into the database should not be that difficult, since it is
expressed as:

known_controls(Time,Taxpayer1,Taxpayer2) ...

When the time is unknown or irrelevant for the period of interest,
express it as a construct that matches all time (i.e., a variable).
-- 
[Forgive me, Father, for I have signed ...]
Bob Dalgleish		...ihnp4!{alberta!}sask!zaphod!bobd
(My mother has disclaimed any knowledge of me)