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[ALL,OEP] Review of "Time Ontology in OWL" and "Time Zone Resource in OWL"

From: Libby Miller <libby@asemantics.com>
Date: Fri, 14 Oct 2005 09:18:36 -0700 (PDT)
To: public-swbp-wg@w3.org
cc: hobbs@isi.edu, pan@isi.edu
Message-ID: <20051014090259.M79014@skutsje.san.webweaving.org>


This message provides my comments on the editor's draft of the Note
"Time Ontology in OWL"[1] and "Time Zone Resource in OWL"[2]

I'm sorry this is rather later than I'd hoped - I hope it's still useful.

I am not an expert on time ontologies but I have worked for a long time
on the Semantic Web Interest group's taskforce on Calendaring, which has
been converting RFC 2445(iCalendar) to RDF/OWL.[3],[4]

In my opinion it would be good to try and get Pat Hayes to review these
documents if he has time - I know he put valuable input into the DAML
Time ontology[5]. Dan Connolly would also be a very useful reviewer if he
has time - he has worked extensively on the SWIG calendaring taskforce and
has implementation experience there.

--

"Time Ontology in OWL"

Overall

This is a huge and difficult subject and I appreciate the authors' work
in scoping the issues to a manageable subset.

I think it's very important to provide usecases as the authors have,
although I think the document requires several more to be compelling. It
would help in particular to emphasise the benefits of an ontology over,
for example, an xml schema; or at least clarify the circumstances where
advantages would occur. It would also be useful to show some examples
which illustrate this ontology mapped to iCalendar, if only for the
reason that iCalendar is very commonly used in PIM applications.

I like the distinction made between Topological Temporal Relations, and
Duration Description and Calendar-Clock Description, distinguishing (I
think) between the ontological constructs and the descriptions we give
to them (e.g. in calendars).

Minor nits:
It would be better for sections to be numbered to allow easier
referencing.
Typos: "meeing"
References need filling in.

Details

Topological Temporal Relations

"Allen's temporal interval calculus" - I'm not familiar with this - I
think a bit more explanation would be useful here, especially as the
reference is not online.

Time Zones

Language is a bit vague: "Probably seconds are not relative to the time
zone."

Use Cases for Time in OWL-S

More would be good (and more general, non-OWL-S usecases, unless the
ontology is specific to that area).

[[
In this example Instant, a subclass of TemporalEntity, would be a better
class to use than TemporalEntity to describe CreditCardExpirationDate,
because the expiration date is actually an instant -- the midnight, of
the day the credit card expires. (This was already changed in the later
release of OWL-S.)
]]

The example should be updated to reflect this.

-------


"Time Zone Resource in OWL"

Overall

It would be good for the authors to take a look at "Working with Time
Zones"[6] which is a very clear description of the issues developers
commonly run into here.

"GMT" should probably be replaced with "UTC" throughout:
[[
Greenwich Mean Time is a widely used historical term, but one that has
been used in several ways. Because of the ambiguity, its use is no
longer recommended in technical contexts.
]][7]

The authors might want to consider having a last updated property or
similar to mitigate cases where daylight savings policies change.

Minor nits:
It would be better for sections to be numbered to allow easier
referencing.


Libby

[1]http://www.isi.edu/~pan/SWBP/time-ontology-note/time-ontology-note.html
[2]http://www.isi.edu/~pan/SWBP/time-zone-note/time-zone-note.html
[3]http://www.w3.org/2002/12/cal/
[4]http://www.w3.org/TR/rdfcal/
[5]http://www.daml.org/listarchive/daml-time/0031.html
[6]http://www.w3.org/TR/2005/NOTE-timezone-20051013/
[7]http://aa.usno.navy.mil/faq/docs/UT.html
Received on Friday, 14 October 2005 16:19:41 GMT

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