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

Re: Clarifying what datatype entailment support means (Re: xsd:float and xsd:decimal)

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Wed, 4 Dec 2002 12:33:09 +0200
Message-ID: <005101c29b80$8a7d45a0$a09216ac@NOE.Nokia.com>
To: "ext pat hayes" <phayes@ai.uwf.edu>
Cc: <w3c-rdfcore-wg@w3.org>

[Patrick Stickler, Nokia/Finland, (+358 40) 801 9690, patrick.stickler@nokia.com]

> I'd suggest the following levels, or distinctions, which correspond 
> roughly to yours.
> 1. Local intra-type information: for each datatype d, all true 
> equations of the form
> Lit-1^^d = Lit-2^^d
> 2. Local inter-type information: As 1, but in addition all true 
> equations of the form
> Lit-1^^d1 = Lit-2^^d2 for d1, d2 in the set of datatypes
> 3. Global inter-type information: As 2., but in addition all subset 
> relationships between value spaces of distinct datatypes in the set.

Hmmm... OK, but this misses one key element, that of whether a given
application has knowledge sufficient for #2 and #3 for all datatypes
for which it provides #1. I.e. the set of datatypes for which it
can provide #3 may be a subset of those for which it can provide #2
which may be a subset of those for which it can provide #1.

Thus, what the three "levels" above are really defining are three
sets of datatype classes.

Of course, the level of support provided can be explicitly captured
by having system-specific assertions, using either classes or 
collection property values.

But it's important that the level of support required by an entailment
test be clear.

> In addition, any of these can also supply RDF properties and 
> undertake to provide extensions for those properties in the form of 
> truthvalues for (some or all) triples of the form
> Lit-1^^d1  <property>  Lit-2^^d2

Right. I would define the three levels of support in this way,
noting simply that the operations provided are defined by the
datatypes in question, but that at the very least, equality is

Received on Wednesday, 4 December 2002 05:34:03 UTC

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