A Short Introduction to Prolog

Re:A Short Introduction to Prolog by JadeNB on Friday August 05, 2011 @10:34AM (#2850207)

Note that there's another flaw: `transitive` as defined only checks if there's one instance of transitivity that works. If you wanted to check (rather than assert) transitivity, you'd need something more like

    transitive(Functor) :-
        not(
            call(Functor,A,B),
            call(Functor,B,C),
            not(call(Functor,A,C))
        ).

(It's been a while since I've Prologged, so I may be forgetting something subtle about why you'd need to use the dribble `=..` to build something callable; but that's not the point, of course!)

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Re:A Short Introduction to Prolog by route66 on Friday August 05, 2011 @10:45AM (#2850251)

Right, I see this as the third way: stating transitivity which must not be asserted explicitly. The question arises what one would want to reach with a call to transitive(descendant).

(aside: the X =.. [F,A,B] is the prolog way of saying eval("F(A,B)"). and make it callable)

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