W3C home > Mailing lists > Public > semantic-web@w3.org > July 2010

Re: Subjects as Literals, [was Re: The Ordered List Ontology]

From: Nathan <nathan@webr3.org>
Date: Fri, 02 Jul 2010 06:46:20 +0100
Message-ID: <4C2D7D2C.1050309@webr3.org>
To: Pat Hayes <phayes@ihmc.us>
CC: Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
Pat Hayes wrote:
> On Jul 2, 2010, at 12:07 AM, Nathan wrote:
>> Pat Hayes wrote:
>>> On Jul 1, 2010, at 11:49 PM, Nathan wrote:
>>>> Pat Hayes wrote:
>>>>> On Jul 1, 2010, at 11:18 AM, Yves Raimond wrote:
>>>>>> "A literal may be the object of an RDF statement, but not the subject
>>>>>> or the predicate."
>>>>> Just to clarify, this is a purely syntactic restriction. Allowing 
>>>>> literals in subject position would require **no change at all** to 
>>>>> the RDF semantics. (The non-normative inference rules for RDF and 
>>>>> RDFS and D-entailment given in the semantics document would need 
>>>>> revision, but they would then be simplified.)
>>>> I have to wonder then, what can one all place in the s,p,o slots 
>>>> without changing the RDF semantics? literal and bnode predicates for 
>>>> instance? variables or formulae as in n3?
>>>> read as: if a new serialization/syntax was defined for RDF what are 
>>>> the limitations for the values of node/object and relationship 
>>>> specified by the RDF Semantics?
>>> None at all. The semantics as stated works fine with triples which 
>>> have any kind of syntactic node in any position in any combination. 
>>> The same basic semantic construction is used in ISO Common Logic, 
>>> which allows complete syntactic freedom, so that the the same name 
>>> can denote an individual, a property, a function and a proposition 
>>> all at the same time.
>>> Pat
>>> PS. Its not a dumb question :-)
>> thus is N3 valid RDF? (I read yes, but want/need to hear that's right!)
> Well, no. It depends what you mean by 'valid RDF'. N3 obviously has a 
> lot of syntax that goes way beyond what is legal in RDF, so its not 
> valid RDF. But if you mean, the basic RDF semantics can be extended to 
> cover all the constructs in N3 (without completely breaking) then yes, 
> it can. In fact, N3 is a subset of Common Logic, and the same basic 
> semantic construction of RDF works for all of CL.  But it would be a 
> real extension, in that all the 'extra' syntax of N3 (notably, the graph 
> literals idea) would need to have its semantics specified explicitly. It 
> wouldn't come for free.
> Hope I've answered your question (?)

perfectly, thanks!
Received on Friday, 2 July 2010 05:47:34 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 19:48:11 UTC