Path: utzoo!attcan!uunet!mcvax!prlb2!kulcs!bimbart
From: bimbart@kulcs.uucp (Bart Demoen)
Newsgroups: comp.lang.prolog
Subject: Re: Propositional Theorem Prover
Message-ID: <1663@kulcs.kulcs.uucp>
Date: 19 May 89 06:45:08 GMT
Reply-To: bimbart@kulcs.UUCP (Bart Demoen)
Organization: Katholieke Universiteit Leuven, Dept. Computer Science
Lines: 30

To my surprise, I have not yet seen any reply to the contribution of
Andre Vellino  <157@bnr-di.UUCP> (perhaps because American people do not
bother to distribute their contribution to Europe)

Let me quote Andre Vellino's conclusion:

> What this may illustrate is that while a procedural language like C 
> probably lends itself well to deterministic algorithms like set-of-
> support resolution, Prolog is better suited to non-deterministic 
> semantic techniques.

If 'better suited' means that you can't write a faster C program implementing
the same non-deterministic algorithm,  then this is wrong: I have a 60 line C
program without tricks that is 5 times faster than the Prolog program presented
by Andre Vellino. I must admit though that my knowledge of what the WAM does to
the Prolog program, helped me in writing the C version.

If 'better suited' just means that it is easier to program in Prolog than in C,
then the article was an overkill: to arrive at this conclusion, there was no
need to have a non-deterministic theoremprover in Prolog that could perform a
certain proof FASTER than deterministic theoremprover in C !

I think the conclusion should have been that deterministic algorithms perform
better on some problems and non-deterministic algorithms perform better on
other problems ... which isn't new either.

The Prolog program can be sped up by a factor of 2 easely by changing the
representation of the formulas and by a small folding exercise.

bimbart@kulcs