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Re: Definitions and provenance and invariance

From: Simon Miles <simon.miles@kcl.ac.uk>
Date: Sun, 19 Jun 2011 12:18:40 +0100
Message-ID: <BANLkTi=JmXXhiQr3eY8JyZE9CutADDsyyg@mail.gmail.com>
To: Provenance Working Group WG <public-prov-wg@w3.org>
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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-- 
Dr Simon Miles
Lecturer, Department of Informatics
Kings College London, WC2R 2LS, UK
+44 (0)20 7848 1166
Received on Sunday, 19 June 2011 11:19:10 GMT

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