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Re: Definitions and provenance and invariance

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Mon, 20 Jun 2011 16:06:20 +0100
Message-ID: <EMEW3|b7d0cff8024854575948c4617c244958n5JG6R08L.Moreau|ecs.soton.ac.uk|4DFF61EC.3060400@ecs.soton.ac.uk>
To: public-prov-wg@w3.org
Simon,
OK with this.  I was going to draft a further simplified definition 
taking this into account.
Luc

On 06/20/2011 01:45 PM, Simon Miles wrote:
> Luc,
>
> I agree with Graham here. I think it's just a matter of wording,
> nothing fundamental, but could lead to people misunderstanding the
> model.
>
> I think the example you give of "identity" is what most people (or at
> least I) would call a "distinguishing feature". Being integral to
> identity is, colloquially, a stronger requirement: it suggests that
> the property is important to understanding what that thing is, not
> merely one that distinguishes the thing from other things. You could
> argue that all distinguishing features are important from some
> perspective, but I suggest that is not how "identity" is commonly
> understood.
>
> As with Graham, I think we're more likely to get correct usage of the
> model if we say nothing at all. I don't see a case for separating
> distinguishing features from invariant properties in general.
>
> Thanks,
> Simon
>
> On 20 June 2011 12:52, Luc Moreau<L.Moreau@ecs.soton.ac.uk>  wrote:
>    
>> You may be right,  can you explain how you understand it?
>> Luc
>>
>> On 06/20/2011 11:22 AM, Graham Klyne wrote:
>>      
>>> It seems we understand the phrase "integral to identity" somewhat
>>> differently, so that's a different reason not use it as part of the
>>> definitions of "things" and "invariant views".  The more you say, the
>>> more room there is for disagreement ...
>>>
>>> #g
>>> --
>>>
>>> Luc Moreau wrote:
>>>        
>>>> 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
>>
>>
>>
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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 15:07:08 GMT

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