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Re: Comments of PROV-DM document (Section 2.1 and 3)

From: Satya Sahoo <satya.sahoo@case.edu>
Date: Tue, 11 Oct 2011 18:39:14 -0400
Message-ID: <CAOMwk6y5cRBKkf=KNUDDKLUVyS3C93C-AWb92k-_RA2DWhxS6A@mail.gmail.com>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Cc: Provenance Working Group WG <public-prov-wg@w3.org>, Paolo Missier <Paolo.Missier@ncl.ac.uk>
Hi Luc,
Thank you for your response! My comments are inline:

>   > Section 2.1 ===== 1. A characterized thing fixes some aspects of a
>   > thing and its situation in the world, so that it becomes possible to
>   > express its provenance, and what causes these specific aspects to be
>   > as such. An alternative characterized thing may fix other aspects, and
>   > its provenance may be entirely different.
>   >
>   > Issue: A "thing" may be characterized differently, that is viewed in
>   > distinct ways, but they are still the same thing. Does the above
>   > statement refer to the "same" thing characterized differently or
>   > distinct things? If the above statement is referring to different
>   > characterization of the same thing, how can their provenance be
>   > "entirely different"?
> The example in section 2.1 illustrates multiple perspectives about a same
> resource with a URL. The provenance is different.
> Ok. I assume "a same resource with a URL" is an instance of an Entity.

> Removed word 'entirely'.
>   >
>   > 2. The provenance of these three characterized things will differ, and
>   > may be along the follow lines: a) the provenance of a report available
>   > at URL may include: the act of publishing it and making it available
>   > at a given location, possibly under some license and access control;
>   > b) the provenance of the version of the report available there today
>   > may include: the authorship of the specific content, and reference to
>   > imported content; c) the provenance of the report independent of where
>   > it is hosted over time may include: the motivation for writing the
>   > report, the overall methodology for producing it, and the broad team
>   > involved in it.
>   >
>   > Issue: Not sure about the issue that is being illustrated/described
>   > here - the three "characterized" things may be the same or
>   > different. In case they are the same thing - Report A (version 1.0,
>   > only one version was ever published) located at URL
>   > www.xyz.com/ReportA_V1.0 can be referred to differently by individual
>   > applications according to their requirements: simply as Report A, or
>   > as version 1.0 of Report A, or www.xyz.com/ReportA_v1.0 - in this case
>   > provenance of the three different characterization will be same.
> The point is not that a same thing is referred to differently by
> applications. It is that we take different perspectives on it.
> An egg vs a set of molecules.
> The way an Entity is referred to/characterized is a perspective. Hence, if
we refer to an instance of an entity as "egg" or "specific set of molecules"
the provenance assertions *may* be exactly the same. The following point
below is an expansion of this point.

>   > Further, we can associate the provenance information for (b) with (a)
>   > also, for example reference to imported content? Similarly for (c) and
>   > (b), (a), for example the motivation to write the report or broad team
>   > involved. I am confused regarding the criteria used to state the
>   > particular provenance information can be associated with (a), (b), or
>   > (c).
> I don't understand this point.
>   > In case they are referring to different things (different reports
>   > located at same URL, different version of same report etc.), the
>   > provenance will be different.
> But that's not the same, we refer to the same report.
> I did not understand this - a specific URL can host multiple versions of
Report A and for some provenance applications their associated provenance
may be different.

>   >
>   > 3. This specification assumes that a partial order exists between
>   > events.
>   >
>   > Issue: Are we excluding overlapping events or events that are
>   > "contained" in other events?
> Events are instantaneous. Hence, there is no overlap and
> containment. Two events occurs at the same instant or not.
> We briefly discussed the issue of ordering of events during the PROV-O/M
call yesterday and the example we discussed may be relevant - an event
"issuance of a traffic ticket to X" can be viewed as instantaneous (total of
traffic tickets issued per year in City A) or stated to have a duration
(10mins). Further, the event may contain events as "ran the stop sign",
"handed over license", "signed the ticket" etc.

We should be able to model all the above set of events in PROV.

>   >
>   > 4. In our conceptualization of the world, punctual events, or events
>   > for short, happen in the world, which mark changes in the world, in
>   > its activities, and in its things.
>   >
>   > Issue: This definition of event seems to be a specialization of a PE?
>   > What are the distinguishing features (if any) of an event vis-a-vis
>   > PE?
> I don't see why they seem to be a specialization. Is it because event
> duration=0?
> We have four types of events, two of which are start and end of PE.
> So, to me they are very distinct from PE.
> Maybe. For example "issuance of a traffic ticket" may be viewed as an
instantaneous event or a event with duration depending on the requirement of
the provenance application.

>   >
>   > Section 3 ===== 1. The wasComplementOf relationship is used to denote
>   > that two entities complement each other, in the sense that they each
>   > represent a partial, but mutually compatible characterization of the
>   > same thing.
>   >
>   > Issue: What does "entity" in the above statement refer to? How can two
>   > entities refer to the same thing - assuming that entity is the term we
>   > agreed to use for "thing"?
> Entity is introduced in previous sentence.
> An entity (expression here!) does not refer to a thing, but represents a
> characterized thing.
> Entity is not defined here as thing (in this version of the document).
> Ok.

>   >
>   > 2. Qualifiers can be associated to relations, namely use and
>   > wasGeneratedBy, in order to further characterise their nature. Role is
>   > a standard qualifier.
>   >
>   > Issue: Are qualifiers associated with relations only - they can be
>   > associated with entities also to further "characterize" it (and
>   > thereby create specialized entities)? What do we mean by "standard
>   > qualifier"?
> Qualifiers are for relations.
> Entities have attributes (characterizing them) (and also annotations)
> standard replaced by pre-defined
>   >
>   > 2. Attributes, qualifiers, and annotation are the main extensibility
>   > points in the model: individual interest groups are expected to extend
>   > PROV-DM by introducing new sets of attributes, qualifiers, and
>   > annotations as needed to address applications-specific provenance
>   > modelling requirements.
>   >
>   > Issue: Since annotation have no prescribed meaning, how can they be
>   > used to extend the model? What is the difference between attributes
>   > and qualifiers? Qualifiers are standard mechanism for specialization
>   > (either entities or relations) - new attributes may or may not be used
>   > to define specialized entities or relations. For example, a new
>   > attribute stating that a Toyota Corolla car hasMileage 100miles does
>   > not necessarily extend the entity Toyota Corolla car?
> I am responding to preceding two points together:

> Annotations: we have given example of use of annotation, where application
> specific annotations give instructions on how to render provenance.
> Ok.

> Attributes are for entities and PEs
> Qualifiers are for relations
> I am not sure I understand - are we just labeling them as different or is
there some "quantified" (by definition) difference between the two? In other
words, are we just saying they are different or is there a reason for
stating that they are different? What happens if an application uses
qualifiers with Entity (e.g. if person X official resides in the White
House, the person is the president of US). Similarly, if the temperature
attribute of a PE has value > 100C, it is a "melting PE".

> There is no concept of "specialized entity" in the model. What do you mean?
> Entity expressions can be complement of other entity expressions
> Not specialized entity - I meant specialization of entity, that is, to
create sub-classes (Agent-> Entity) or sub-properties.



Assistant Professor
Division of Medical Informatics, School of Medicine
& EECS Department, School of Engineering
Case Western Reserve University
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Received on Tuesday, 11 October 2011 22:39:46 UTC

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