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Re: datatypes and MT

From: Dan Connolly <connolly@w3.org>
Date: Fri, 02 Nov 2001 09:09:00 -0600
Message-ID: <3BE2B70C.C5E881E4@w3.org>
To: Pat Hayes <phayes@ai.uwf.edu>
CC: w3c-rdfcore-wg@w3.org, pfps@research.bell-labs.com
Pat Hayes wrote:
[...]
> Let me try to first summarize the MT changes that I managed to
> extract from the pfps/ph interchange

I object to this proposal entirely.

> For example, the following graph written in bnode-style:
> 
> aaa bbb _:1 .
> _:1 rdf:value "345" .
> _:1 rdf:type xsd:integer .
> 
> would be boiled down into:
> 
> aaa bbb _:1:"345" .
> _:1 rdf:type xsd:integer .

Let's not muck up the model theory like this. Let's
keep it simple: abstract syntax:
	terms:
		constants (URIs w/fragids)
		string literals
		bnodes (existentially quantified variables)
	statement:
		term term term.
	formula:
		statement*
with the traditional interpretation structure
(with the IEXT() indirection trick).

That's it.

If we want to say "my shoe size is some
integer whose decimal representation is '10'", that's easy:

	:me :shoeSize _:x.
	_:x rdf:type :integer.
	_:x :decimalRep "10".

which can be written in RDF/xml 1.0 very easily:

	<rdf:Description rdf:about="#me">
	  <shoeSize>
            <integer decimalRep="10"/>
	  </shoeSize>
        </rdf:Description>

To fill in the details... let dt:
be the namespace of XML Schema primitive datatypes,
and let rdfs:str be a new property
that relates XML Schema datatype to strings;
it's unambiguous over each of the primitive datatypes;
in the case of dt:string, it's the identity relation.

	<rdf:Description rdf:about="#me">
	  <shoeSize>
            <dt:decimal rdfs:str="10"/>
	  </shoeSize>
        </rdf:Description>

I use rdfs:str rather than rdf:value because M&S 1.0
(and some dublin core documentation) suggest that
rdf:value is for some wierd sort of currying.
I'd be happy to revoke the crazy suggestion about
currying and say that rdf:value works ala
rdfs:str above... but note that some folks
in www-rdf-logic pointed out that rdf:value
sorta goes backwards: one would think
that the value of a numeral is a number,
but rdfs:str goes from numbers to numerals.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Friday, 2 November 2001 10:09:03 EST

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