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Re: PROV-ISSUE-462 (entity-definition-precision): Definition o entity may be too liberal [prov-dm]

From: Daniel Garijo <dgarijo@delicias.dia.fi.upm.es>
Date: Tue, 23 Oct 2012 12:54:10 +0200
Message-ID: <CAExK0De-0UBKXB8EkBtG42cNvToU5uSu4k9n16iPP3b0HUbXLw@mail.gmail.com>
To: Luc Moreau <l.moreau@ecs.soton.ac.uk>
Cc: Paul Groth <p.t.groth@vu.nl>, "public-prov-wg@w3.org" <public-prov-wg@w3.org>
I think that it would be appropriate to have some examples in the FAQ too.

In fact, a good example for "scruffy" provenance are the entities
described in DC (many of them would not comply to the prov constraints),
while for "proper" provenance we could the entities generated in a
scientific
workflow.

Just an idea though.

Best,
Daniel

2012/10/23 Luc Moreau <l.moreau@ecs.soton.ac.uk>

>  Hi Paul,
> The FAQ maybe?
> Luc
>
>
> On 10/22/2012 07:26 PM, Paul Groth wrote:
>
> Hi Luc,
>
>  This is quite a nice clarification. I wonder if there's somewhere we can
> use this without adding it to the document? I think the definitions stand
> on their own as they now stand.
>
>
>  ==Off topic==
> In general, there's a "philosophy" that's never been really stated
> somewhere that drops out of these clarifications that I think the working
> group shares but may not be articulated concisely in a single document. I
> think (some) of the key points of the philosophy are:
>
>  1) Scruffy ---> Proper
> 2) Identify the fixed bits your talking about
> 3) There's multiple kinds of provenance descriptions, we provide a
> substrate for all
> 4) PROV is extensible (it's a substrate)
>
>  Maybe this should go in the overview document?
>
>  cheers
> Paul
>
>
>
>
>
> On Mon, Oct 22, 2012 at 11:50 AM, Luc Moreau <l.moreau@ecs.soton.ac.uk>wrote:
>
>>  Dear all,
>>
>> I have drafted a response to the following issue. See
>>
>> http://www.w3.org/2011/prov/wiki/ResponsesToPublicComments#ISSUE-462_.28Definition_of_Entity.29
>>
>>  I will implement the changes once I have a confirmation
>> the group is happy with them, and they satisfactorily address the issue.
>>
>>
>>  ISSUE-462 (Definition of Entity)
>>
>>    - Original email:
>>    http://lists.w3.org/Archives/Public/public-prov-comments/2012Jul/0009.html
>>    - Tracker: http://www.w3.org/2011/prov/track/issues/462
>>    - Group Response:
>>       - The term 'entity' is intentionally defined in a liberal manner
>>       to avoid restricting users expressivity. Obviously, it shouldn't be too
>>       liberal, otherwise it would be all encompassing, without clear semantics.
>>       - The term 'entity' (and associated notions such as 'alternate',
>>       'specialization') have been the subject of intense debate by the Working
>>       Group, and the definition reflects the compromise reached by the Working
>>       Group.
>>       - The term 'aspect' is not used here with a technical meaning and
>>       should be understood with its dictionary meaning 'A particular part or
>>       feature of something'.
>>       - PROV-Constraints, in its rationale section, expands on the
>>       notion of entity.
>>       - While an object/thing may change over time, an entity fixes some
>>       aspects of that thing for a period of time (in between its generation and
>>       invalidation). As opposed to other models of provenance (such as OPM), an
>>       entity is not an absolute state snapshot. Instead, it is a kind of partial
>>       state, just fixing some aspects. The rationale for this design decision is
>>       that it is quite challenging to find absolute state snapshots that do not
>>       change: the location of a file on a cloud changes, the footer of this Web
>>       page changes (as more people access it), etc. Hence, by allowing *
>>       some* aspects (as opposed to all) to be fixed, the PROV concept of
>>       'entity' is easy to use.
>>       - We distinguish an 'aspect' from an 'attribute'. An
>>       attribute-value pair represents additional information about an entity (or
>>       activity, agent, usage, etc). In the case of an entity, attribute-value
>>       pairs provide descriptions of fixed aspects. So, the term 'aspect' refers
>>       to properties of the thing, whereas the term 'attribute' refers to its
>>       description in PROV.
>>       - PROV does *NOT* assume that all fixed aspects are described by
>>       attribute-value pairs. So, there may be some fixed aspects that have not
>>       been described. Obviously, without description, it's difficult to query or
>>       search over them.
>>       - According to PROV Constraint key-object (constraint 23), an
>>       entity has a set of attributes given by taking the union of all the
>>       attributes found in all descriptions of that entity. In other words, PROV
>>       does not allow for different attribute-value pairs to hold in different
>>       intervals for a given entity.
>>       - The attribute-value pairs of an entity provide information for
>>       some of the fixed aspects of an entity.
>>          - *This point may not have been clear, and requires text
>>          modification*. (see below)
>>        - A specific attribute of an entity is its identity. It is also
>>       assumed that it holds for the duration of the entity lifetime.
>>          - *This point may not have been clear, and requires text
>>          modification*. (see below)
>>
>>
>>    - References:
>>       - PROV constraints rationale:
>>       http://www.w3.org/TR/2012/WD-prov-constraints-20120911/#entities--activities-and-agents
>>       - entity/specialization/alternate definitions:
>>       http://www.w3.org/2011/prov/wiki/SpecializationAlternateDefinitions
>>       - Resolution on entity/specialization/alternate:
>>       http://www.w3.org/2011/prov/meeting/2012-05-03#resolution_2
>>       - Key Constraints definition:
>>       http://www.w3.org/TR/2012/WD-prov-constraints-20120911/#dfn-key-constraints
>>       - Key-Object constraint 23:
>>       http://www.w3.org/TR/2012/WD-prov-constraints-20120911/#key-object
>>     - Proposed Changes to the document:
>>       - http://www.w3.org/TR/prov-dm/#entity.attributes: instead of
>>       "representing additional information about this entity." write
>>       "representing additional information about the fixed aspects of this
>>       entity."
>>       - http://www.w3.org/TR/prov-dm/#term-identifier: add the
>>       following.
>>          - Entity, Activity, and Agent have a mandatory identifier. Two
>>          entities (resp. activities, agents) are equal if they have the same
>>          identifier.
>>          - Generation, Usage, Communication, Start, End, Invalidation,
>>          Derivation, Attribution, Association, Delegation, Influence have an
>>          optional identifier. Two generations (resp. usages, communications, etc.)
>>          are equal if they have the same identifier.
>>
>>
>>
>>
>> Luc
>>
>>
>> On 07/25/2012 08:16 AM, Provenance Working Group Issue Tracker wrote:
>>
>> PROV-ISSUE-462 (entity-definition-precision): Definition o entity may be too liberal [prov-dm]
>> http://www.w3.org/2011/prov/track/issues/462
>>
>> Raised by: Paul Groth
>> On product: prov-dm
>>
>> This is the issue for http://lists.w3.org/Archives/Public/public-prov-comments/2012Jul/0009.html
>>
>> from Jacco van Ossenbruggen
>>
>>
>>
>>
>>
>> --
>> 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
>>
>>
>
>
>  --
> --
> Dr. Paul Groth (p.t.groth@vu.nl)
> http://www.few.vu.nl/~pgroth/
> Assistant Professor
> - Knowledge Representation & Reasoning Group |
>   Artificial Intelligence Section | Department of Computer Science
> - The Network Institute
> VU University Amsterdam
>
>
> --
> 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 Tuesday, 23 October 2012 10:54:42 UTC

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