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Datatyping Summary V4

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Mon, 04 Feb 2002 13:00:50 +0000
Message-Id: <5.1.0.14.0.20020204112006.02e0a428@0-mail-1.hpl.hp.com>
To: RDF Core <w3c-rdfcore-wg@w3.org>
An updated summary of the datatyping issues, as I currently understand them.

Changes:

   B1  now disputed
   B7  status changed to agreed
   B9  withdrawn
   B10 added "say what you mean"

Issue B1:
=========

status: disputed by Sergey.  Sergey you owe us an explanation of why.

In S, if one wants to use both idiom A and idiom B, e.g.

<mary> <age> "10" .
<age> <rdfs:range> <xsd:integer.lex> .

and

<mary> <ageD> _:a .
_:a <xsd:integer.map> "10" .

two properties have to be used, <age> and <ageD>, in this example.

I believe there is a agreement that this is a difference between the
two proposals. Indeed, it may be said that the main aim of TDL is
to avoid requiring different properties for these different idioms.

Can't Live With: PatrickS


Issue B2: Multiple Lexical Representations of a data value
==========================================================

status: agreed that S-A allows this and TDL does not.

S, idiom A, permits multiple lexical representations of a data value:

_:i <xsd:double> "10.1" .
_:i <xsd:double.de> "10,1" .


Issue B3: the self entailment issue
===================================
status: Withdrawn in favour of B4:

From:

http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jan/0410.html

[[I accept the reasoning above; it doesn't address my objection;
it' just shows that my example wasn't very good. Sergey's
example makes the point better:]]

B9 also added in response to Graham's request.


Issue B4 - TDL breaks existing code
===================================

status: facts agreed; significance disputed.

This is similar to B3. I've changed the example slightly from Sergey's.

Under TDL, consider the graph:

_:f <rdf:type> <film> .
_:f <dc:Title> (_, "10") .
<mary> <age> (_, "10").

Does not entail:

_:x <dc:Title> _:y .
_:z <age> _:y .

Can't Live With: DanC


Issue B5: Storage Requirements
===============================

status: disputed.

TDL requires significantly more storage to implement.


Issue B6: S requires 4 URI's be registered for each data type
=============================================================
S requires that for each datatype 4 URI's be registered
datatype
datatype.lex
datatype.val
datatype.map

Sergey: Do you agree this is the case? If not, how many URI's are required 
to implement ALL the idioms of S and coexist in the same model.


Issue B7: Complexity
====================

status: agreed

S has several ways of expressing the same thing. An RDF processor has to be 
aware of them all. Supported by Jeremy's error cases message

http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jan/0397.html

and a message from Andy Seaborne to rdf comments:

http://lists.w3.org/Archives/Public/www-rdf-comments/2002JanMar/0058.html


Issue B8: S-B encourages logically (sic) errors in the
application type processing.
=======================================================

status: ?

Given:

_:f <rdf:type> <film> .
_:f <dc:Title> "10" .
<mary> <age> "10" .

an application 'knows' that the range of <age> is an integer so it 'knows' 
that mary has <age> 10. Under S-B, running a query:

?x <dc:Title> ?y .
?z <age> ?y .

will return ?x = _:f and ?z = <mary>, and knowing that the age of <mary> is 
10, may conclude that the title of the film is also 10.

Can't Live With: Jeremy


Issue B9: In TDL a document does not entail itself
==================================================

status: Withdrawn.

Under TDL, does:

<foo> <dc:Title> "W3C" .

entail

<foo> <dc:Title> "W3C" .

yes.


Issue B10: Say what you mean
============================

status: ?

The concern here is that in TDL, a literal denotes a pair consisting of a 
value and a lexical representation of that value.  The problem is then that 
the german representation of floating point number, e.g. "10,5" is 
different from the english representation, e.g. "10.5".

Thus under TDL a german 10 and a half is a different thing from an english 
10 and a half.


More formally, under TDL:

   <foo>      <eg:size>   _:s1 .
   _:s1       <rdf:value> "10,5" .
   _:s1       <rdf:type>  <xsd:double-de> .

   <bar>      <eg:size>   _:s2 .
   _:s2       <rdf:value> "10.5" .
   _:s2       <rdf:type>  <xsd:double> .

does not entail:

   <foo> <eg:size> _:s .
   <bar> <eg:size> _:s .

Does anyone dispute the facts, or that this is a significant issue?
Received on Monday, 4 February 2002 08:01:58 EST

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