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RE: Please review OWL-Time document

From: <Simon.Cox@csiro.au>
Date: Mon, 20 Feb 2017 02:45:32 +0000
To: <L.Svensson@dnb.de>
CC: <public-sdw-wg@w3.org>
Message-ID: <d7cb27a677d844738312fba13dd47ba0@exch1-mel.nexus.csiro.au>
Regarding ISSUE-125 and ISSUE-126

I have followed Lars suggestion and added :inXSDDateTimeStamp to complement :inXSDDateTime and have annotated the latter owl:deprecated="true"
This should improve computability while protecting legacy instances. 

If I hear no objections by the end of the week, I'll close these two issues. 


-----Original Message-----
From: Svensson, Lars [mailto:L.Svensson@dnb.de] 
Sent: Thursday, 12 January, 2017 19:34
To: Cox, Simon (L&W, Clayton) <Simon.Cox@csiro.au>
Cc: public-sdw-wg@w3.org
Subject: RE: Please review OWL-Time document

Hello Simon,

On Wednesday, January 11, 2017 10:39 PM, Simon.Cox@csiro.au [mailto:Simon.Cox@csiro.au] wrote:

> 1) Actually there is no domain or range for time:after, just the 
> inverseOf relationship to time:before which does have them.
> Of course the domain and range is implied by the inverseOf relationship.
> But I'm not sure what the current recommended style is - in 2006 I 
> guess domain and range were omitted if an inverseOf relationship was declared.
> But it requires a reasoner to understand this. Is there a general 
> assumption that reasoning shall always be assumed?

Perhaps we can always assume reasoning, but not always OWL reasoning (although it's named OWL Time wo perhaps we _can_ assume that...). If I remember the discussion about SSN and SOSA correctly, we wanted to keep the option open to perform RDFS reasoning only (and thus added rdfs:Class and rdfs:Property at the appropriate places) and people more knowledgeable than me can probably tell if that makes sense here, too.
> I had not intended to change this (though I had mistakenly added a 
> domain and range for time:after in the ttl file, which I have now reverted).
> If the group thinks a change is merited, then I am happy to insert 
> domains and ranges all round where they are already implied by inverseOf relationships.

Yes, an OWL reasoner can of course infer the correct domain and range from the owl:inverseOf relation, but an RDFS reasoner can't. I guess it boils down to the question if it makes sense to use OWL Time without OWL.

> 2) Processed.


> 3)   Regarding ISSUE-125 - I agree that xsd:dateTimeStamp is preferable, but the
> problem is backward compatibility.
> If the rdfs:range of inXSDDateTime is changed from xsd:dateTime (which 
> is still part of OWL2 btw) to xsd:dateTimeStamp, then what are the 
> implications for existing data in which the timezone is omitted?
> Does it become 'invalid' in some way?

Ah, now I understand: it's about existing instance data. Could it be a solution to mark time:inXSDDateTime as deprecated and add a new property time:inXSDDateTimeStamp with range xsd:dateTimeStamp and domain time:Instant? That way existing data would still be valid while we communicate that it's not good practice to use time:inXSDDateTime anymore.



> -----Original Message-----
> From: Svensson, Lars [mailto:L.Svensson@dnb.de]
> Sent: Thursday, 12 January, 2017 07:43
> To: Cox, Simon (L&W, Clayton) <Simon.Cox@csiro.au>; 
> public-sdw-wg@w3.org
> Subject: RE: Please review OWL-Time document
> Simon, all,
> On Thursday, December 22, 2016 6:37 AM, Simon.Cox@csiro.au 
> [mailto:Simon.Cox@csiro.au] wrote:
> > The Editors draft of the OWL-Time specification can be considered 
> > for release as a second public working draft.
> > http://w3c.github.io/sdw/time/
> I use the time after today's super-short meeting to make some very 
> minor comments on this very concise and informative document: cudos to the editors!
> 1)	time:before has domain and range time:TemporalEntity which time:after
> doesn't. I guess that time:after should have domain and range, too.
> 2)	There is a typo in the URI given in the OWL-2 reference [1]. The text is ok, but
> the href says http://www.w3.org/TR/turtle/owl2-quick-reference/#Built-in_Datatypes .
> I think that should be 
> http://www.w3.org/TR/owl2-quick-reference/#Built-in_Datatypes
> 3)	Regarding ISSUE-125 and backward compatibility with OWL-1, there was a mail
> from Antoine Zimmermann where he said: "The standard Web Ontology 
> Language is now OWL 2. Let us forget about OWL 1" [2]. So I think it 
> should be safe to update the spec to use xsd:dateTimeStamp.
> [1] https://w3c.github.io/sdw/time/#OWL-2
> [2] 
> https://lists.w3.org/Archives/Public/public-sdw-wg/2016Nov/0069.html
> Best,
> Lars
Received on Monday, 20 February 2017 02:46:45 UTC

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