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Re: RDFCore WG: Datatyping documents

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 05 Feb 2002 10:32:19 -0500
To: patrick.stickler@nokia.com
Cc: www-rdf-logic@w3.org
Message-Id: <20020205103219Z.pfps@research.bell-labs.com>
From: Patrick Stickler <patrick.stickler@nokia.com>
Subject: Re: RDFCore WG: Datatyping documents
Date: Mon, 04 Feb 2002 23:19:27 +0200


[...]

> > Right now the document says that the meaning of
> > Unicode nodes are pairs consisting of Unicode strings and data values.
> > Without quick, clear, and forceful statements to the contrary, TDL will be
> > inextricably associated with this meaning,.
> 
> Fair enough.
> 
> Perhaps you would like to offer the underpinnings of an MT that
> you feel more precisely captures the fundamental intent of the
> TDL pairing model. It would be welcome, I'm sure.

I believe that all of the proposals that I have floated have this
intent.  The various proposals have differing details, based on how they
deal with the issues raised by things like XML Schema union datatypes and
xsi:type attributes.

[...]

> Cheers,
> 
> Patrick


The following is taken from one of my proposals for a Web Ontology
Language.


A datatyping scheme is a collection of datatypes, DT.
For each datatype d in DT there are four components:
	U(d), URI for the datatype;
	L(d), the lexical space for the datatype;
	V(d), the value space for the datatype; and
	LV(d) : L(d) -> V(d), the lexical-to-value mapping for the datatype.
Given a datatyping scheme, let L = union over d in DT of L(d), lexical values
			       V = union over d in DT of V(d), data values
			       LV = union over d in DT of LV(d)

An [...] interpretation, I, over a datatyping scheme DT 
[consists] of R, nonempty 		the domain of resources [...]
	      P <= R, nonempty		properties
	      C <= R, nonempty		classes	      
	      EXT : P -> 2^(Rx(RuV))	property extensions
	      CEXT : C -> 2^(RuV)	class extensions
	      S : N -> R		mapping from names to denotation

D1  DT <= C
D2  S(Ud) = d   for d in DT
D3  S(swol:Datatype)    in   C\DT
D4  CEXT(S(swol:Datatype)) = DT
D5  for d in DT    CEXT(d) = Vd

[The interpretation of a literal node with label TEXT is constrained to be
an element of LV(text).]


Now this does have some problems with datatyping schemes that have
``rogue'' datatypes that cause LV to be too loose.  These problems can be
alleviated by taking XML Schema local or schema typing information from XML
documents, and using that to uniquely determine the datatype mapping (much
in the way that Pat is suggesting with dtype).

The important thing to note here is that the denotation of a literal node
is in the value space of a datatype.

peter
Received on Tuesday, 5 February 2002 10:33:37 GMT

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