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Re: formal semantics strawman

From: Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk>
Date: Mon, 26 Sep 2011 12:40:35 +0100
Message-ID: <CAPRnXtk4V9aJQFbbtkO0KiV=Psfsxu50LY6Pc-6XSwjCZx3t9Q@mail.gmail.com>
To: James Cheney <jcheney@inf.ed.ac.uk>
Cc: "Myers, Jim" <MYERSJ4@rpi.edu>, Graham Klyne <GK@ninebynine.org>, W3C provenance WG <public-prov-wg@w3.org>
On Fri, Sep 23, 2011 at 16:38, James Cheney <jcheney@inf.ed.ac.uk> wrote:

> Thanks Stian for your detailed comments.  You seem to agree with my view on most of the questions where I thought Jim and I might disagree (e.g. that entities are statements about "real things")  So I am a little surprised that Jim agrees - I am not sure whether your and Jim's comments reflect a different view than mine that means we need to change the strawman, or simply saying the same things in different ways.

I am glad we are coming to an agreement. Perhaps it is just a simple
matter of precision wording.


> Instead of discussing the rest point by point, can I ask whether the following statements are controversial:
>
> 1.  Entity assertions (when written down as instances of the data model) describe facts about things that are true (or at least the asserter believes to be true).

Right.


> 2.  Things have attributes that can change over time.

Yup. Or that *may* change over time.


> 3.  Entity assertions describe attribute values that are fixed (and may be construed as identifying the thing) during the associated time interval.

Yes, except that we might also want to include other (informational)
fixed attributes which are not meant to be identifying the thing. If
we need to distinguish these is the "characterizing attributes"
question.


It would not be very practical to assert attribute values which are
not (observed/interpreted as) fixed within the interval
observed/described by the asserter, so I think we can fairly ignore
those. If needed to assert that "at some point the entity had this
attribute value", they can be asserted on a narrower entity which
wasComplementOf the original entity.


> 4.  Entity assertions have identities that allow us to refer to / link different assertions within the data model, but may or may not be related to globally meaningful URIs.

I agree. And where they do relate to globally meaningful URIs, then
the attribute values given are not necessarily globally always as
stated - they are only asserted to be such for this asserter within
this provenance account.

(The same asserter might later produce a different provenance account
with different attribute values for same URIs)


> If we agree on the above things, then I think the formal semantics strawman and data model reflect this common viewpoint as-is, and just needs to be updated to reflect the current data model draft and include illustrating examples.  If not, please suggest alternative statements that you do agree with (or changes to the semantics).

No, this sounds good to me. Jim?




-- 
Stian Soiland-Reyes, myGrid team
School of Computer Science
The University of Manchester
Received on Monday, 26 September 2011 11:41:33 GMT

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