RE: ssn: value add of dul and whther the O&M alignment should be normative

The topic discussed  as agenda item 2 in the meeting today was "O&M alignment "normative" or "non-normative"" .
https://www.w3.org/2015/spatial/wiki/Meetings:SSN-Telecon20170124

I don't understand why it was derailed into all this old ground about dul yet again.

However, on the very specific  question of whether or not the dul alignment should be normative or not in our spec, I have said many times (and sorry to repeat it again here, but to be fair I don't think the question has strictly been raised  for discussion before, so this may be new to some),  that in my own personal opinion the dul alignment need not be normative in the spec. I can't think of any reason why it should be normative, and I prefer the message that being non-normative perhaps sends, that is that the alignment is not necessary in order  to use ssn according to the  standard. That is, it makes the alignment  "optional", I think.
But if this implies to some that it should not appear in the spec, then I reserve the right to change my opinion on this matter.

On the question of any formal contradiction with any O&M alignment that we might or might not  want to make --- personally I don't care. Nobody will want to use both at the same time. We have no such use case.

However, as the OGC O&M standard is a UML model and textual descriptions of the meaning of the terms,   I see no possibility of a formal contradiction anyway.

If, however, we follow the path of adopting some O&M alignment as an ontology  fragment then I would make exactly the same argument that such an alignment should not be "normative" . That is, that it should not be normative because it should be "optional" - it is a service to our users to provide it.
OTOH if it is text-based as I expect (like our mapping table on the wiki) AFAIAC it may as well be normative (I think) because I can't think of a way that, even if it is normative, it forces a standards-compliant user to do something with  it. But maybe that is just my lack of imagination.

So for me, the answer to the real question that was on the agenda is - it depends. Let's wait and see what Simon proposes with ACTION-255.

-Kerry


From: Krzysztof Janowicz [mailto:janowicz@ucsb.edu]
Sent: Wednesday, 25 January 2017 11:10 AM
To: Kerry Taylor <kerry.taylor@anu.edu.au>; SDW WG Public List <public-sdw-wg@w3.org>
Subject: Re: ssn: value add of dul

Hi Kerry,

I would feel really, really uncomfortable to invite Aldo to question him about the user base and stability of DUL. We took the decision to uncouple (new) SSN from DUL a long, long time ago and now we are discussing whether the 'alignment' should be normative or non-normative and what exactly we mean by 'alignment'. This matters because it may impact our alignment with O&M. If we mean an alignment in terms of OWL subclassing and so forth, then there is not such thing as an 'informal' or 'optional' alignment as all axioms in OWL are born equal. Also, please note that O&M is an international standard developed by the OGC on the topic at hand, namely observations and so on, while DUL is a foundational ontology. Btw, this is not a statement about the quality of DUL and Aldo's work (for which I have the highest respect). Finally, if we have a normative DUL alignment and it is in a new namespace and so is SSN, do we have to provide implementation details for each part of the alignment? I recall that this is an argument that you tend to use in other cases.

Best,
Krzysztof

On 01/24/2017 03:49 PM, Kerry Taylor wrote:
Dear SDW,
I don't know why, but today in the ssn meeting the question of whether ssn should be aligned to dul or not was brought up again.  I think it was covering old, well-resolved ground that is reflected in our current published WD, but this seems not to be agreed.

Therefore I propose we invite the author of dul (actually DOLCE+DnS Ultralite) Aldo Gangemi to an ssn meeting to present on the virtues/stability/value/users/use etc of dul in association with ssn.

Kerry





--

Krzysztof Janowicz



Geography Department, University of California, Santa Barbara

4830 Ellison Hall, Santa Barbara, CA 93106-4060



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