W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > December 2002

Re: Should rdf:value have a semantics??

From: Jos De_Roo <jos.deroo.jd@belgium.agfa.com>
Date: Thu, 5 Dec 2002 10:07:43 +0100
To: "pat hayes <phayes" <phayes@ai.uwf.edu>
Cc: "Patrick Stickler" <patrick.stickler@nokia.com>, w3c-rdfcore-wg@w3.org
Message-ID: <OF70D788A5.DD9084D1-ONC1256C86.0031F7E9-C1256C86.003226DE@agfa.be>


> Heres a rewrite of the section which hopefully will overcome the
> objections. Feel free to suggest modifications (including, delete it
> altogether :-)
>
> Pat
> ----------
> The intended use for rdf:value is to indicate that some entity is
> associated with a particular value, usually indicated by a literal,
> from some predefined range of possible values. Examples of this kind
> of use are given in [RDF-PRIMER]. It can used, for example, to
> associate some quantity with a literal representing the 'amount' of
> the quantity, such as a weight in kilograms or a length in yards;
> associating a textual object with a Dewey Decimal code; or for
> indicating a part or model number in some contextual range. In all
> these cases the subject of the triple will typically be a blank node
> denoting the quantity or object in question, and whose other
> properties indicate the context in which the value is to be
> understood. For example:
>
> <ex:thing> <ex:weight> _:x .
> _:x rdf:value "12.36"^^xsd:float .
> _:x <ex:weightUnit> <ex:kilogram> .
>
> <ex:doc> <dc:subject> _:x .
> _:x rdf:value "020-Library Science" .
> _:x <ex:classification> "DeweyDecimalCode" .
>
> <ex:thing> <ex:assembly> _:x .
> _:x rdf:value "1234" .
> _:x <ex:scope> "Model2001-super"
>
> Since the subject of the relevant triple can be any quantity, and the
> object can either be a plain literal indicating a textual
> representation of the amount or a typed literal denoting the
> numerical value of the amount, there is no way to give a formal
> specification of this intended usage.
>
> Users are cautioned that any such usage will be context-dependent and
> is liable to be misunderstood if removed from its context. A single
> triple involving rdf:value has no particular meaning in isolation.
> The use of rdf:value in this way can often be replaced by the use of
> more complex RDF constructions or more explicit user-defined
> vocabulary in order to avoid such ambiguities.
>
> -----
>
> Also at the end of 4.3 (datatype entailments: informative) Ive added
> this, but it can be deleted if people think it doesnt belong (I've
> already had queries as to why this form wasnt mentioned in the MT,
> though.)
>
> ------
> The informal meaning for rdf:value outlined in section 2.3.4 suggests
> the following equivalence, which we mention here for completeness as
> it represents a style of existing usage. We emphasize however that it
> is not strictly valid since rdf:value has no formal semantics, and
> that in any case the three-triple graph below does not have exactly
> the same meaning as the first triple since it does not uniquely
> associate the plain literal with the datatype:
>
> aaa ppp "sss"^^ddd .
>
> <-->
>
> aaa ppp _:x .
> _:x rdf:value "sss" .
> _:x rdf:type ddd .

??? would that also apply for ppp being rdf:value
e.g. for above example

  _:x rdf:value "12.36"^^xsd:float .
=>
  _:y rdf:value _z .
  _:z rdf:value "12.36" .
  _:z rdf:type xsd:float .

I haven't seen an appealing case for rdf:value so far...

>
> -------
> --
> ---------------------------------------------------------------------
> IHMC                                                   (850)434 8903
home
> 40 South Alcaniz St.                              (850)202 4416   office
> Pensacola                                              (850)202 4440
fax
> FL 32501                                                    (850)291 0667
cell
> phayes@ai.uwf.edu                 http://www.coginst.uwf.edu/~phayes
> s.pam@ai.uwf.edu   for spam

-- ,
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Thursday, 5 December 2002 04:08:19 EST

This archive was generated by hypermail pre-2.1.9 : Wednesday, 3 September 2003 09:54:48 EDT