RE: I've implemented the changes to xsd:dateTimeStamp

Hello,

 

Yes: there is just one value space, but date-time values in different time zones
are not identical. They are equal for the purposes of facets. Furthermore, a
date-time value with a time zone is neither equal nor identical to a date-time
value without a time zone. (I.e., the values with and without the time zone are
completely independent.)

 

Regards,

 

            Boris

 

  _____  

From: Alan Ruttenberg [mailto:alanruttenberg@gmail.com] 
Sent: 30 March 2009 14:22
To: Boris Motik
Cc: W3C OWL Working Group
Subject: Re: I've implemented the changes to xsd:dateTimeStamp

 

Hello Boris,

 

By my read, the situation regarding the value space of the
dateTime/dateTimeStamp is that there is a single value space, but that some
values are incomparable.

 

"Values from any one date/time datatype using the seven-component model (all
except  <http://www.w3.org/TR/xmlschema11-2/#duration> duration) are ordered the
same as their  <http://www.w3.org/TR/xmlschema11-2/#vp-dt-timeOnTimeline>
.timeOnTimeline. values, except that if one value's
<http://www.w3.org/TR/xmlschema11-2/#vp-dt-timezone> .timezoneOffset. is absent
and the other's is not, and using maximum and minimum
<http://www.w3.org/TR/xmlschema11-2/#vp-dt-timezone> .timezoneOffset. values for
the one whose  <http://www.w3.org/TR/xmlschema11-2/#vp-dt-timezone>
.timezoneOffset. is actually absentchanges the resulting (strict) inequality,
the original two values are incomparable."

 

 

Is that your understanding?

 

-Alan

 

http://www.w3.org/TR/xmlschema11-2/#theSevenPropertyModel

 

On Sat, Mar 28, 2009 at 11:15 AM, Boris Motik <boris.motik@comlab.ox.ac.uk>
wrote:

Hello,

I have just implemented the change to the semantics of xsd:dateTimeStamp. While
doing so, I took the liberty to clean up the datatype section a bit. The main
problem was that the section was written as if it were defining various
datatypes; for example, it said "The facets of xsd:string are such-and-such".
This is clearly wrong: the facets of xsd:string are as defined in the XML Schema
document, and there is nothing we can do to change this. Another problem was
with the tables with the semantics of facets which were superfluous.

To clarify all this, I have explicitly stated now that the sections defines only
owl:real and owl:rational, and that the specification merely reuses the
definitions of various datatypes. Hence, I've removed any attempts to (re)define
XML Schema datatypes and have just added a bunch of examples by means of which
we discuss certain consequences of their definition.

I have also added an example in the section for functional data properties where
we now discuss the difference between equality and identify.

The diff showing the changes in the Syntax document is here:
http://www.w3.org/2007/OWL/wiki/index.php?title=Syntax
<http://www.w3.org/2007/OWL/wiki/index.php?title=Syntax&diff=20865&oldid=20838>
&diff=20865&oldid=20838

No other document was changed in relation to this.


Finally, I would just like to point out that we should include xsd:dateTime into
our datatype map now. There is no good technical reason not to do so;
furthermore, most of the ontologies out there use xsd:dateTime rather than
xsd:dateTimeStamp so, according to our current solution, such ontologies are not
OWL 2 ontologies. I hope we can discuss and resolve this at the next teleconf.

Regards,

       Boris