[net.lang.prolog] Cut, var, nonvar, and Goebel's

reddy@uiucdcs.CS.UIUC.EDU (07/08/86)

/* Written 12:03 pm  Jul  2, 1986 by rb@cci632.UUCP in uiucdcs:net.lang.prolog */

Now I'm a little confused.  Aren't any goals which refer to uninstantiated
variables, which are later instantiated, potentially both true and false?
...
	Rex B.
/* End of text from uiucdcs:net.lang.prolog */

They are.  But, if p(X) succeeds without instantiating X, it means that p(X)
is true for ALL instantiations of X.  A goal p(c) where c is a constant
should not then turn out to be false.

reddy@uiucdcs.CS.UIUC.EDU (07/09/86)

/* Written 12:03 pm  Jul  2, 1986 by rb@cci632.UUCP in uiucdcs:net.lang.prolog */
I normally think of a cut symbol as an uninstantiated variable that gets
instantiated to false.
	Rex B.
/* End of text from uiucdcs:net.lang.prolog */

Can you elaborate on this?  I can't see how you can think of cut as a
variable.