Re: N3 rules: literals as subject and object in built-in functions

Rules are necessary an extension to RDF.
It is not possible to define rules within the semantics of RDF alone.
It is possible to consider blank nodes as variables though,
but only as local variables.
But of course things like @forAll and @forSome are extensions.
Formulas are supported however and they can be translated to RDF using lists and reifications. 
Furthermore, all builtins are extensions to RDF.

Guido Naudts





----- Original Message ----
From: Jeff Thompson <jeff@thefirst.org>
To: jos.deroo@agfa.com
Cc: public-cwm-talk@w3.org
Sent: Monday, May 28, 2007 6:45:58 PM
Subject: Re: N3 rules: literals as subject and object in built-in functions


jos.deroo@agfa.com wrote:
> Jeff Thompson wrote:
>  > To clarify my question, in RDF syntax:
>  > http://www.w3.org/TR/rdf-syntax-grammar/#section-Syntax-intro
>  > it says "RDF literals, which can only be object nodes, become either XML
>  > element text content or XML attribute values."
>  > So, is the restriction that only object nodes can be literals merely
>  > a limitation of the XML representation? (If so, a good reason to get
>  > away from XML....)
> 
> In http://www.w3.org/DesignIssues/Notation3.html
> Appendix: N3 Subsets
> you can find that in the following N3 subsets
> 1/ N3 RDF
> 2/ N3 Rules
> 3/ N3
> literal subj is allowed
> e.g. 7 a n:prime.

Thanks.  I saw this and it added to my confusion.  I know that N3 introduces
things that are not represented in valid RDF.  For example formulas, and
even variables like ?x.  The fact that "literal subj" has to be explicitly
listed makes me wonder if it is another non-RDF addition.  Furthermore,
Turtle is "another subset, for only expressing RDF", but it doesn't allow
literal subj.  However it easily could, which makes me wonder whether it is
left out because it is not valid RDF.

- Jeff








       
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Received on Wednesday, 30 May 2007 12:19:51 UTC