🚀 go-pugleaf

In article <meskes.714916931@ulysses> meskes@ulysses.informatik.rwth-aachen.de (Michael Meskes) writes:
>All the answers are quite interesting 
	Thank you :-)
but the don't solve the problem.
	At least we've tried !
>As far as I know Prolog is turing-complete and the proofs I know don't use
>the Cut. So why isn't it possible to solve this problem im Prolog?

	Because "turing completeness" means that you can  emulate a TM
by a pure-prolog program after appropriate encoding.

so if you can express p(X) q(X) and r(X) in Pure Prolog, there is a 
TM which computes the same thing as IF p(X) THEN q(X) ELSE r(X),
(which is is computable by a Prolog+cut+... interpreter) and thus
there is a Pure Prolog program which computes the same results. 

But this existence theorem doesnt provide a way to turn
a Prolog+cut+... into a pure prolog program by high-level
source-to-source program transformations, in other words
you desperately need to know the text of p(X), q(X) and s.o.

I think (not really sure of that) there is the same kind of problems
if you want to express the exception mechanism in purely functional
languages. 

>If you still think I want you to do my homework try not to answer. 

?- not(toAnswer).
yes :-)

Michel
-- 
Michel BILLAUD                 :  billaud@geocub.greco-prog.fr
Departement d'Informatique     :  phone W: 56.84.57.92  // 56.84.69.22
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