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From: avg@diablo.UUCP
Newsgroups: net.lang.prolog
Subject: Re: Standard behavior?
Message-ID: <157@diablo.ARPA>
Date: Tue, 24-Jun-86 22:30:57 EDT
Article-I.D.: diablo.157
Posted: Tue Jun 24 22:30:57 1986
Date-Received: Fri, 27-Jun-86 07:06:57 EDT
References: <6500005@uicsl> <29700028@uiucdcs> <768@aimmi.UUCP> <498@cheops.OZ>
Reply-To: avg@diablo.UUCP (Allen VanGelder)
Organization: Stanford University
Lines: 15

| In article <29700028@uiucdcs> reddy@uiucdcs.UUCP writes:
| | To rggoebel@watdragon:
| | You can try explaining cut, var and nonvar logically.  If you do it
| | successfully, you could become a star of the logic programming community.
| 
| In all humility, and with a strong chance of getting it all wrong here I
| go:
|	....
Then alan@cheops.OZ (Alan Tonisson) shoots down the attempt.

A simple way to convince yourself that these are non-logical is to remember
that AND and OR are commutative and associative.  Thus a clause has the
same logical meaning under all permutations of its literals.
But clearly, clauses with cut, var, and nonvar do not have this property,
in general -- the order of subgoals DOES matter.  QED