RE: URIS for Literals (was: Re: referendum on httpRange-14 (was RE: "information resource"))

And it would be valid for any sw agent to infer 

   VAL_URI owl:sameAs RDF_LITERAL

for any given val: URI 'VAL_URI' where 'RDF_LITERAL' corresponds 
to the RDF literal value identified by 'VAL_URI'.

e.g. given either the URI <val:(integer)10> and/or the RDF literal
"10"^^xsd:integer, a sw agent can validly infer, based on the
definition of the val: URI scheme itself, that

   <val:(integer)10> owl:sameAs "10"^^xsd:integer .

etc.

Patrick


> -----Original Message-----
> From: www-tag-request@w3.org 
> [mailto:www-tag-request@w3.org]On Behalf Of
> ext 
> Sent: 01 November, 2004 09:20
> To: chris@w3.org; noah_mendelsohn@us.ibm.com
> Cc: GK@ninebynine.org; joshuaa@microsoft.com; skw@hp.com; 
> timbl@w3.org;
> www-tag@w3.org
> Subject: RE: URIS for Literals (was: Re: referendum on 
> httpRange-14 (was
> RE: "information resource"))
> 
> 
> 
> 
> 
> > -----Original Message-----
> > From: www-tag-request@w3.org 
> > [mailto:www-tag-request@w3.org]On Behalf Of
> > ext Chris Lilley
> > Sent: 29 October, 2004 23:32
> > To: noah_mendelsohn@us.ibm.com
> > Cc: Graham Klyne; Joshua Allen; Stuart Williams; Tim Berners-Lee;
> > www-tag@w3.org
> > Subject: Re: URIS for Literals (was: Re: referendum on 
> > httpRange-14 (was
> > RE: "information resource"))
> > 
> > 
> > 
> > On Friday, October 29, 2004, 6:41:02 PM, noah wrote:
> > 
> > nuic> Chris Lilley writes:
> > 
> > >> With the proviso that I would prefer
> > >> 
> > nuic> 
> > data:text/plain;charset="utf-8",some%20percent%20escaped%20lit
> > eral%20value
> > 
> > nuic> I think the above is a plausable way of carrying a 
> > literal which is a
> > nuic> sequence of unicode chars.
> > 
> > Yes - that is exactly what I thought it was good for, 
> string literals.
> > 
> > 
> > nuic>  I wonder whether there is any need to have a
> > nuic> URI that represents the member of the type xsd:integer 
> > that has the
> > nuic> numeric value 10, for example?
> > 
> > It might be useful (and I agree that the above form would not be
> > suitable)
> > 
> > 
> > 
> > nuic>   http://www.w3.org/2004/SchemaSimpleTypes/Integer/value/12
> > 
> > nuic>   http://www.w3.org/2004/SchemaSimpleTypes/Integer/lexical/012
> > 
> > nuic>   http://www.w3.org/2004/SchemaSimpleTypes/Integer/12
> > 
> > I agree those forms are much preferable, 
> 
> Why would they be preferable to any other form of URI? 
> Despite the fact
> that humans might recognize that they seem to pertain to 
> literal values,
> the principle of URI opacity would preclude any agent (or human) from
> concluding that they actually do identify literal values, 
> since the http:
> URI scheme says nothing about such interpretations.
> 
> > I think it is. Further, other types can be created that were not in
> > W3C XML Schema, a benefit of using URIs for them.
> 
> Exactly.
> 
> What is needed is a dedicated URI scheme which provides for reliable
> interpretation of URIs as identifying particular literal 
> values (plain,
> language tagged, or typed). I proposed such a URI scheme quite some
> time ago, but it was eclipsed at that time by the work on 
> typed literals
> in RDF. 
> 
> E.g.
> 
> --
> 
> val: - Literal Value URI Scheme
> 
> VAL_URI          = "val:" PLAIN_LITERAL
> VAL_URI          = "val:" LANGTAG_LITERAL
> VAL_URI          = "val:" TYPED_LITERAL
> PLAIN_LITERAL    = LEXICAL_FORM
> LANGTAG_LITERAL  = LEXICAL_FORM "(" LANGTAG ")"
> TYPED_LITERAL    = "(" DATATYPE ")" LEXICAL_FORM
> LEXICAL_FORM     = {URL encoded lexical form}
> DATATYPE         = {URL encoded datatype URI}
> LANGTAG          = {a valid xml:lang value}
> 
> --
> 
> Thus, allowing literals to be expressed unambiguously by URI e.g.:
> 
>    val:some%20plain%20literal
>    val:some%20language%20tagged%20literal(en)
>    val:(http%3A%2F%2Fwww%2Ew3%2Eorg%2F2001%2FXMLSchema%23integer)12
>    val:(http%3A%2F%2Fwww%2Ew3%2Eorg%2F2001%2FXMLSchema%23boolean)true
>    val:(http%3A%2F%2Fwww%2Ew3%2Eorg%2F2001%2FXMLSchema%23lang)fi
>    
> val:(http%3A%2F%2Fwww%2Ew3%2Eorg%2F2001%2FXMLSchema%23string)y
> ada%20yada%20yada
>    val:(http%3A%2F%2Fexample%2E.com%2Fblargh)booga
> 
> which correspond to the following RDF literals (using 
> N-Triples notation):
> 
>    "some plain literal"
>    "some language tagged literal"@en
>    "12"^^<http://www.w3.org/2001/XMLSchema#integer>
>    "true"^^<http://www.w3.org/2001/XMLSchema#boolean>
>    "fi"^^<http://www.w3.org/2001/XMLSchema#lang>
>    "booga"^^<http://example.com/blargh>
> 
> The val: URI scheme could give explicit support to the 
> pre-defined XML Schema
> datatypes, allowing the datatype component to correspond 
> solely to the localname
> portion of the XML Schema datatype, e.g. adding the following 
> to the above grammar:
> 
> DATATYPE         = {XML Schema pre-defined datatype localname}
> 
> resulting in support for abbreviated forms such as
> 
>    val:(integer)12
>    val:(boolean)true
>    val:(lang)fi
>    etc...
> 
> yet any arbitrary datatype still remains fully supported.
> 
> Because the interpretation of all URIs based on the val: URI 
> scheme would be
> defined by the URI scheme itself, agents (and humans) are 
> then free to conclude
> which literal values those particular URIs identify -- 
> insofar as e.g. any
> datatype in question is recognized (since e.g. if you don't know
> what datatype <http://example.com/blargh> is, you can't know 
> which value
> the lexical form "booga" corresponds to in any case).
> 
> Ideally, literals could be used as subjects in RDF 
> statements, but until
> such usage is legal, a dedicated literal value URI scheme 
> such as defined
> above could provide a great deal of utility, without violating the
> principle of URI opacity.
> 
> Cheers,
> 
> Patrick
> 
> --
> 
> Patrick Stickler
> Nokia, Finland
> patrick.stickler@nokia.com
>  
> 
> 
>

Received on Monday, 1 November 2004 08:10:01 UTC