Re: FOL, ZFC, NGB and Prolog

In article <1118163658.286358.92980@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
"Tom" <tkorna@xxxxx> wrote:

>Jim Spriggs wrote:
>> Tom wrote:
>> >
>> > .... Prolog is,
>> > merely, FOL in executable notation.
>>
>
>: No, Prolog is much more restrictive than FOL.
>
>I see. I thought that it is, as is FOL, Turing complete.

The issue here isn't about computational power but about expressiveness.
For example, there is no direct Prolog translation of this FOL:
Ax (P(x) v Q(x))

For another example, Prolog's negation-as-failure means that Prolog a model
of some domain relies on the "closed world assumption": if you can't prove
that something is true then it must be false. This is different from full
FOL.


>Kindest regards,
>Tom

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Relevant Pages

  • Re: predicate in a predicate
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  • Re: FOL, ZFC, NGB and Prolog
    ... >> Tom wrote: ... Prolog is much more restrictive than FOL. ... Prolog, like all reasonable programming languages, is Turing complete. ...
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  • Re: predicate in a predicate
    ... Prolog is somehow from Horn Clauses, they can have at most one ... how can I convert the FOL that have two positive ... With negation as failure you can go beyond horn clauses. ... positivity check is ok, so this amounts to prolog as: ...
    (sci.logic)
  • Re: FOL, ZFC, NGB and Prolog
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  • Re: FOL, ZFC, NGB and Prolog
    ... > Tom wrote: ... >> merely, FOL in executable notation. ... Prolog is much more restrictive than FOL. ...
    (sci.logic)
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