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From: u-reddy@utah-cs.UUCP (Uday U-reddy)
Newsgroups: net.lang.prolog
Subject: Re: Cut, var, nonvar, and Goebel's stardom
Message-ID: <3830@utah-cs.UUCP>
Date: Tue, 24-Jun-86 21:45:12 EDT
Article-I.D.: utah-cs.3830
Posted: Tue Jun 24 21:45:12 1986
Date-Received: Fri, 27-Jun-86 04:06:10 EDT
References: <6500005@uicsl> <29700028@uiucdcs> <270@ubc-cs.UUCP>
Reply-To: u-reddy@utah-cs.UUCP (Uday U-reddy)
Organization: University of Utah CS Dept
Lines: 24

In article <270@ubc-cs.UUCP> andrews@ubc-cs.UUCP (Jamie Andrews) writes:
>     Well, as far as cut is concerned:  it's fairly easy to explain it
>"logically", though not as a predicate or a goal, which is what I assume
>you meant.
>
>     Var and nonvar are essentially the read and write annotations of
>Parlog and similar languages.  Again it's difficult to explain them as
>predicates, but not as control primitives.
>
>--Jamie.

Sorry Jamie, I fail to understand this completely.  We had lengthy
discussions, in Prolog digest last year, on what is logical and what isn't.
But, to cut (!) the long story short, something is logical if it has a
logical value, like "true", or "false", or even nonstandard logical values
like "neither true nor false" or "both true and false" or whatever. 
Further, the logical value of any logical thing should be preserved under
instantiation.

Now, I am not sure if what you are saying has anything to do with the
logical-ness of these constructs.

Uday Reddy
reddy@uiuc.arpa  uiucdcs!reddy