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From: lang@zeta.PRC.Unisys.COM (Francois-Michel Lang)
Newsgroups: comp.lang.prolog
Subject: Re: Determining order of argument unification
Message-ID: <8210@burdvax.PRC.Unisys.COM>
Date: 4 Nov 88 21:41:42 GMT
References: <8192@burdvax.PRC.Unisys.COM> <629@quintus.UUCP>
Sender: news@PRC.Unisys.COM
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In article <629@quintus.UUCP>, ok@quintus.uucp (Richard A. O'Keefe) writes:
> In article <8192@burdvax.PRC.Unisys.COM> lang@zeta.PRC.Unisys.COM (Francois-Michel Lang) writes:
> >Is it possible to determine (by writing a Prolog program)
> >which of these two orders is used for given a Prolog system,
> >and, if so, how?
...
> However, the answer is *no*.  The reason is that there are lots of other
> things a Prolog system could do.
...

I think my original question remains valid,
if we assume that the Prolog system one is running
(1) does indeed use left -> right or right -> left order,
(2) uses it consistently, and
(3) can't handle cyclic terms.
This last point is very easy to check.
----------------------------------------------------------------------------
Francois-Michel Lang
Paoli Research Center, Unisys Corporation lang@prc.unisys.com (215) 648-7256
Dept of Comp & Info Science, U of PA      lang@cis.upenn.edu  (215) 898-9511