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Re: Formal semantics draft

From: James Cheney <jcheney@inf.ed.ac.uk>
Date: Mon, 9 Jan 2012 12:06:43 +0000
Cc: public-prov-wg@w3.org
Message-Id: <414189D8-FCCE-4B94-8407-4E6ADDFFE25D@inf.ed.ac.uk>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Hi,

Sorry to have let this slide.  Comments interspersed below.

On Dec 22, 2011, at 4:40 PM, Luc Moreau wrote:

> Hi James,
> 
> Thanks for drafting the semantics, it will help us pin down issues in
> the data model.
> 
> I have a few general questions first, about the alignment of the
> semantics and the data model.
> 
> As agreed in the call, I am sharing them by email.
> 
> 1. PROV-DM identifies three levels
>    1. things in the world
>    2. entities, which are characterized things
>    3. entity records, which are the records we create as part of a provenance record
> 
>   It seems that things are not mentioned in your document. I believe they are
>   important to define specialization/alternates
> 

As discussed on the 22nd, I agree that this is a potential mismatch.  Graham and Stian suggested one way to resolve it, namely taking the "things in the world" to be those entities that are not views of other entities.  Or we could make this distinction explicit by defining separate sets of Things and Entities.

I have added a subsection summarizing the problem to the draft:

http://www.w3.org/2011/prov/wiki/FormalSemanticsStrawman#Objects_vs._Things_vs._entities

and I will try to draft the two alternatives so that we can compare them soon.

> 2. PROV-DM tends to talk about events, whereas your semantics focuses on time.
>   PROV-DM assumes the existence of a mapping from events to time.  Is it possible
>   to align both?
> 

Currently, events are explicit in the semantics, and there is a function mapping events to time instants.  

http://www.w3.org/2011/prov/wiki/FormalSemanticsStrawman#Events

andevents are mentioned in Use,Generation, Start, End records.  So I'm not sure how this could be improved to align better with PROV-DM (i.e., I thought what I had already done was aligning with PROV-DM).  Can you localize the comment to a specific part of the draft?

> 3. Used or Generated don't seem to have activities. It seems
>   counter-intuitive.  Can you clarify?
> 

I'm also not sure I understand this question.  There was a typo in the discussion of generation

http://www.w3.org/2011/prov/wiki/FormalSemanticsStrawman#Generation

which I have fixed, but both Generation and Use sections discuss the activity parameter to the relationship.  If you still see the problem, can you localize it?

--James 
-- 
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Received on Monday, 9 January 2012 12:08:59 UTC

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