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RE: OW-Time - "hasDuration max 1" restriction on TemporalEntity?

From: <Simon.Cox@csiro.au>
Date: Mon, 30 Jan 2017 20:55:23 +0000
To: <fd@w3.org>, <chris.little@metoffice.gov.uk>
CC: <public-sdw-wg@w3.org>
Message-ID: <6fb1599c7e004db49af7769f954a463c@exch1-mel.nexus.csiro.au>
Thanks for careful reading Francois. 

1. "An interval can have multiple duration descriptions, but can only have one duration". - this text was copied over verbatim from the 2006 version https://www.w3.org/TR/2006/WD-owl-time-20060927/#duration However, OWL-Time 2006 did not have the class :Duration or the predicate :hasDuration, so the comment was conceptual and had no effect on the implementation. 

We introduced the class :Duration which allows for a (simpler) numeric description of duration using one of the Temporal Units. But this still does not make it unique, since 90 mins = 1.5 hours etc. so it is not desirable to limit the cardinality of the :hasDuration property on Intervals. 

Probably what we need is to modify the language to make it clear what is meant. How about 

"The extent of an interval can be given using multiple duration descriptions or individual durations, but these should all describe the same amount." 

2. "the spec uses `only`, `exactly`, `max` and `value` a lot in these "subclass of" sections" - this is Manchester syntax, as indicated in the introductory sentence to Chapter 4. If you missed that, then probably others will too. Do you have a suggestion how to make this more prominent? 

Simon 

-----Original Message-----
From: Francois Daoust [mailto:fd@w3.org] 
Sent: Tuesday, 31 January, 2017 04:07
To: Cox, Simon (L&W, Clayton) <Simon.Cox@csiro.au>; 'Chris Little' <chris.little@metoffice.gov.uk>
Cc: public-sdw-wg@w3.org
Subject: OW-Time - "hasDuration max 1" restriction on TemporalEntity?

Hello again,

Still looking at the Time Ontology, the Duration section [1] says that "An interval can have multiple duration descriptions, but can only have one duration".

I was expecting to see this "can have only one duration" restriction appear somewhere in the ontology but that does not seem to be the case. Doesn't this translate into a "time:hasDuration max 1" subclass of row in the definition of "time:TemporalEntity" [2]?

Also, a side "rookie" question: the spec uses `only`, `exactly`, `max` and `value` a lot in these "subclass of" sections. I initially thought I would find a definition of these terms somewhere (in OWL, RDFS, Turtle, SHACL, or elsewhere), but that does not seem to be the case. I see how they get translated into an "owl:Restriction" construct in the Turtle file that describes the ontology, which all makes sense to me, but is this pseudo-language defined somewhere?

Thanks,
Francois.

[1] http://w3c.github.io/sdw/time/#duration

[2] http://w3c.github.io/sdw/time/#time:TemporalEntity



Received on Monday, 30 January 2017 20:56:06 UTC

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