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Re: Definitions and provenance and invariance

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Mon, 20 Jun 2011 08:39:15 +0100
Message-ID: <EMEW3|ff6e0a5df792b1612d98ac07a78eedcen5J8dK08L.Moreau|ecs.soton.ac.uk|4DFEF923.3010203@ecs.soton.ac.uk>
To: public-prov-wg@w3.org
Hi Simon and Graham,

I added a response to Graham's comment on invariant property and identity.
See http://www.w3.org/2011/prov/wiki/ConceptInvariantViewOnThing#Comments

Cheers,
Luc

On 06/19/2011 12:18 PM, Simon Miles wrote:
> Graham,
>
> OK, thanks for the clarification. I agree with your point, and am also
> sympathetic to your discomfort with everything invariant being
> "integral to identity".
>
> Thanks,
> Simon
>
>
> On 17 June 2011 23:00, Graham Klyne<GK@ninebynine.org>  wrote:
>    
>> Simon Miles wrote:
>>      
>>> Graham, Stian, all,
>>>
>>> I might be confused, but this seems a more complex model than the one
>>> proposed by Jim and Luc.  Why do we need to both a Dynamic Resource
>>> and a View Resource?  I can't see any meaningful difference between
>>> them either in Graham's definition or Stian's (helpful) concrete
>>> example.  What is the point of saying anything about a mutable
>>> property, e.g. "content of DynamicResource i0", when any assertion of
>>> a mutable property's value will not always hold anyway?
>>>        
>> Speaking for myself... I used the terms "Dynamic" and "View" as labels to
>> distinguish their roles in the structure given.  I would not choose to model
>> them as different types.
>>
>> My point, expressed in terms of Stian's example, is that the notion we have been
>> calling IVP is present in the viewOf relation rather than inherent in the
>> resources themselves.  This was my point, which I think is also at the heart of
>> the proposal by Jim and Luc.
>>
>> I happen to think that the definition as proposed in the wiki at
>> http://www.w3.org/2011/prov/wiki/ConceptInvariantViewOnThing#ACCEPTED_at_teleconference_2011-06-16
>> is over-specified (I've added some comments there).  But having expressed that
>> reservation, I'm content to let them stand pro tem for the purposes of discussion.
>>
>> #g
>> --
>>
>>
>>      
>>> On 16 June 2011 15:39, Stian Soiland-Reyes
>>> <soiland-reyes@cs.manchester.ac.uk>  wrote:
>>>        
>>>> On Tue, Jun 14, 2011 at 12:09, Graham Klyne<GK@ninebynine.org>  wrote:
>>>>
>>>>          
>>>>> Suppose that the "Dynamic resource has a number of different observable
>>>>> properties, some of which do not change over time, and others which do.
>>>>>   Then the View resource would be a resource for with a similar set of
>>>>> properties such that do not change over time, but correspond to the dynamic
>>>>> resource properties at a given time (including properties that do not change
>>>>> over time).  If the Dynamic resource does not change over time, then it may
>>>>> also serve as its own view resource:  the has view property can be
>>>>> reflexive.
>>>>>
>>>>> The provenance resource is an assertion about the properties of the view
>>>>> resource.  I believe the key requirement that we try to capture is that the
>>>>> properties about which the provenance resource makes assertions are
>>>>> invariant - there is no assertion in the provenance resource which is not
>>>>> always true of the view resource.
>>>>>            
>>>> This is a very beautifully simple model which I think we should keep
>>>> in mind before digging too much into the exciting discussions.
>>>>
>>>>
>>>>
>>>> "simplified" for the File example:
>>>>
>>>>
>>>> :i0 a :DynamicResource ;
>>>>   :name "/home/towns.txt" ;
>>>>   :content [ :bytes "" ] ;
>>>>   :creator :Alice .
>>>>
>>>>
>>>> :i0View a :ViewResource ;
>>>>    :viewOf :i0 ;
>>>>    :name "/home/towns.txt" ;
>>>>    :creator :Alice .
>>>>
>>>>
>>>> # Metadata stored in filesystem
>>>> :i0Provenance a :ProvenanceResource ;
>>>>    :provenanceOf :i0View ;
>>>>    :account :FileSystem ;
>>>>    :processes (
>>>>       [  :agent :Alice ;
>>>>          :location :server1 ;
>>>>          :process :fileCreation ;
>>>>          :time "2011-06-15 18:00:01 UTC"  ]
>>>>     ) .
>>>>
>>>> # however the log file claims the file was created on her workstation
>>>> (not server), and 1 second later (clocks out of sync?)
>>>>
>>>> :i0Provenance2 a :ProvenanceResource ;
>>>>    :provenanceOf :i0View ;
>>>>    :account :ServerLogFile ;
>>>>    :processes (
>>>>       [  :agent :Alice ;
>>>>          :location :AliceWorkstation;
>>>>          :process :fileCreation ;
>>>>          :time "2011-06-15 18:00:02 UTC"  ]
>>>>     ) .
>>>>
>>>>
>>>>
>>>> ### New graph - Content changed
>>>>
>>>> :i0 a :DynamicResource ;
>>>>   :content [ :bytes "New York\nLos Angeles\n"  ] ;
>>>>   :name "/home/towns.txt" ;
>>>>   :creator :Alice ;
>>>>   :readBy (:Alice :Bob :Charles :David)
>>>>
>>>>
>>>> :i2 a :ViewResource ;
>>>>   :viewOf :i0 ;
>>>>   :name "/home/towns.txt" ;
>>>>   :creator :Alice ;
>>>>   :content [ :bytes "New York\nLos Angeles\n"  ] .
>>>>
>>>> :i2Provenance a :ProvenanceResource ;
>>>>   :provenanceOf :i2 ;
>>>>    :account :FileSystem ;
>>>>    :processes (
>>>>       [  :agent :Alice ;
>>>>          :location :server1 ;
>>>>          :process :fileCreation ;
>>>>          :time "2011-06-15 18:00:03 UTC"  ]
>>>> # Lost as :FileSystem metadata only keeps last-modified
>>>> #     [   :agent :Alice ;
>>>> #         :location :server1 ;
>>>> #         :process :fileWrite ;
>>>> #         :time "2011-06-15 18:00:03 UTC"  ]
>>>>      [
>>>>          #  :agent :Bob;  - not recorded as only owner/creator is kept
>>>>          :location :server1 ;
>>>>          :process :fileWrite ;
>>>>          :time "2011-06-15 18:14:12 UTC"  ]
>>>>     ) .
>>>>
>>>>
>>>> So say there are additional mutable properties such as :readBy above -
>>>> would you consider those propagating into the view as mutable
>>>> properties? There could be another view over :i2 for the file before
>>>> it was read by Charles, where :readBy is an immutable property.
>>>>
>>>> The example graph above does not distinguish between mutable and
>>>> immutable properties - perhaps we shouldn't as they could be difficult
>>>> to find, identify and measure.
>>>>
>>>> Here :readBy is not kept by neither the log file or file system and is
>>>> a kind of conceptual property - it could be discovered by simply
>>>> asking everyone who could have read it, or inferred from traced file
>>>> usage, like if its sent in an email.
>>>>
>>>> --
>>>> Stian Soiland-Reyes, myGrid team
>>>> School of Computer Science
>>>> The University of Manchester
>>>>
>>>>
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>>>>
>>>>          
>>>
>>>
>>>        
>>
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>>      
>
>
>    

-- 
Professor Luc Moreau
Electronics and Computer Science   tel:   +44 23 8059 4487
University of Southampton          fax:   +44 23 8059 2865
Southampton SO17 1BJ               email: l.moreau@ecs.soton.ac.uk
United Kingdom                     http://www.ecs.soton.ac.uk/~lavm
Received on Monday, 20 June 2011 07:39:48 GMT

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