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From: fgm@icdoc.UUCP (Frank McCabe)
Newsgroups: net.lang.prolog
Subject: Re: prolog questions
Message-ID: <240@ivax.icdoc.UUCP>
Date: Mon, 2-Sep-85 13:17:49 EDT
Article-I.D.: ivax.240
Posted: Mon Sep  2 13:17:49 1985
Date-Received: Wed, 4-Sep-85 06:53:03 EDT
References: <496@cadre.ARPA>
Reply-To: fgm@icdoc.UUCP (Frank McCabe)
Organization: Dept. of Computing, Imperial College, London, UK.
Lines: 22
Xpath: icdoc ivax

Reference to can PROLOG do x? (where x is a universally quantified variable)

There isn't anything that you can't do in PROLOG.

In particular in micro-PROLOG there is a hook in the system which invokes 
a user fdefined PROLOG program whenever an error trap occurs.  One of the 
available errors is "No definition for...". It is quite simple to modifiy
the error handler program so that whenever such an error occurrs, the
user is given the opportunity of a) answering the question, b) defining 
the program on the spot or c) something completely different.

In fact this is the default mode on the expoert system package APES.

Uncertainty is handled in two aspects: 1) extra parameters are added to your
program to encode the probabilities and their computations (i.e. you 
reason exactly about uncertainties) and 2) all these extra parameters can
be hidden from the programmer by the proper use of grammars and front ends
which take the  'uncertain' rules and convert into regular PROLOG rules.

This too has been done as an experiment at IC.

Frank McCabe.