RE: feedback sought on ISSUE-529, ISSUE-524, ISSUE5-519, ISSUE-523

+1

________________________________
From: Luc Moreau [l.moreau@ecs.soton.ac.uk]
Sent: 09 October 2012 12:02
To: public-prov-wg@w3.org
Subject: feedback sought on ISSUE-529, ISSUE-524, ISSUE5-519, ISSUE-523


Dear all,

I drafted a response to ISSUE-529, ISSUE-524, ISSUE5-519, ISSUE-523.
It can be found at
http://www.w3.org/2011/prov/wiki/ResponsesToPublicComments#PROV-DM_issues_involving_inheritance,
and is copied below for information.

Feedback welcome!
Cheers,
Luc


--
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<mailto:l.moreau@ecs.soton.ac.uk>
United Kingdom                     http://www.ecs.soton.ac.uk/~lavm




PROV-DM issues involving inheritance
[edit<http://www.w3.org/2011/prov/wiki/index.php?title=ResponsesToPublicComments&action=edit&section=34>]ISSUE-529 (Empty Collection)

 *   Original email: http://lists.w3.org/Archives/Public/public-prov-wg/2012Sep/0119.html
 *   Tracker: http://www.w3.org/2011/prov/track/issues/529
 *   Group Response:
    *   In an open world context, absence of the relation hadMember(c,e) does not imply that a collection c is empty. Hence, the group introduced a class EmptyCollection to indicate when a collection is empty.
    *   Figure 11, like UML diagrams, is informative. It shows that Collection and EmptyCollection are linked with Entity, by means of a Generalization association. Therefore, a Collection and EmptyCollection are also entities with an id and attributes.
    *   Concretely, prov-dm (prov-n) sees all the sub-types (e.g. prov:type='prov:Collection' ) as type information is expressed by the prov:type attribute.
    *   The handling of these subtypes is consistent with other subtypes in the model, e.g. revision, softwareAgent, etc
    *   Prov-dm, as a conceptual model, leaves the implementation of these inherited types to concrete serializations.
 *   References:
 *   Implemented changes:
    *   Changed the text to indicate that PROV defines no collection specific attributes.
    *   http://dvcs.w3.org/hg/prov/diff/9fb92e012cec/model/prov-dm.html
 *   Original author's acknowledgement:

[edit<http://www.w3.org/2011/prov/wiki/index.php?title=ResponsesToPublicComments&action=edit&section=35>]ISSUE-524 (Bundle/Collection)

 *   Original email: http://lists.w3.org/Archives/Public/public-prov-wg/2012Sep/0114.html
 *   Tracker: http://www.w3.org/2011/prov/track/issues/524
 *   Group Response:
    *   The group has already addressed ISSUE-504, explaining that Bundles are not Collections.
 *   References:
    *   ISSUE-504: http://www.w3.org/2011/prov/wiki/ResponsesToPublicComments#ISSUE-504_.28collection.2Fbundle.29
 *   References:
 *   Proposed changes:
    *   Changed the text to indicate that PROV defines no collection/bundle specific attributes.
    *   http://dvcs.w3.org/hg/prov/diff/9fb92e012cec/model/prov-dm.html
 *   Original author's acknowledgement:

[edit<http://www.w3.org/2011/prov/wiki/index.php?title=ResponsesToPublicComments&action=edit&section=36>]ISSUE-519 and ISSUE-523 (Influence Inheritance)

 *   Original email: http://lists.w3.org/Archives/Public/public-prov-wg/2012Sep/0109.html
 *   Original email: http://lists.w3.org/Archives/Public/public-prov-wg/2012Sep/0113.html
 *   Tracker: http://www.w3.org/2011/prov/track/issues/519
 *   Tracker: http://www.w3.org/2011/prov/track/issues/523
 *   Group Response:
    *   First, a reminder that UML diagrams are informative.
    *   The prov-constraints document provides normative information about Influence. See Inference 15.
    *   For instance, the following inference is permitted, allowing to infer a wasInfluencedBy statement from a wasGeneratedBy statement.

IF wasGeneratedBy(id; e,a,_t,attrs) THEN wasInfluencedBy(id; e, a, attrs).


 *
    *   Whatever appears as id/attributes in wasGeneratedBy becomes also id/attributes in wasInfluencedBy
    *   Whatever appears as entity (e) in wasGeneratedBy becomes influencee in wasInfluencedBy
    *   Whatever appears as activity (a) in wasGeneratedBy becomes influencer in wasInfluencedBy
    *   Given this, prov-dm should define the minimalist characteristics for wasInfluencedBy in a technology agnostic way.
    *   Inheritance is a way of implementing Inference 15 of prov-constraints (and this approach was successfully followed by prov-o), but it does not have to be implemented that way. For instance, a rule based system could simply implement Inference 15 without requiring inheritance. The current prov-xml schema does not define WasGeneratedBy as an extension if Influence. A record based system may not rely on inheritance.
    *   As the author suggests, inheritance would imply that attributes are inherited by the children relation. It is not the case that wasGeneratedBy has influencer/influencee attributes, but instead, we want to show that they correspond to activity/entity in that case.
    *   Given this, the document should be changed as follows:
       *   The UML diagram in Figure 8 should not show a Generalization association between WasGeneratedBy (and others) and WasInfluencedBy.
       *   A table should be introduced showing which attributes in Generation/Usage/etc are influencer or influencee.
    *   With these changes, the issue raised by the author is no longer applicable: it is no longer the case that wasGeneratedBy etc can be used anywhere between agent/activity/entity.
    *   For the comment "The notion of influence is useful for the PROV model, but it is unclear whether this is intended to represent an extension point for adopters of the spec. How should it be implemented?", we have shown with prov-o, prov-n, and prov-xml various ways of implementing Influence. According to Section 6, Influence is not seen as an extensibility point of the model, instead, it is seen as a means to express influence in PROV without being specific about its nature. We note the following, quoted from the specification:
       *   It is recommended to adopt these more specific relations when writing provenance descriptions. It is anticipated that the Influence relation may be useful to express queries over provenance information.
 *   References:
    *   Inference 15: http://www.w3.org/TR/2012/WD-prov-constraints-20120911/#influence-inference
    *   Current xml schema: http://dvcs.w3.org/hg/prov/file/f0e8bc2ae457/xml/schema/prov.xsd
    *   Extensibility section: http://www.w3.org/TR/prov-dm/#extensibility-section
 *   Implemented changes:
    *   Changed figure 8, removing Generalization relation between WasGeneratedBy,etc and WasInfluencedBy
    *   Added table 7.
    *   http://dvcs.w3.org/hg/prov/diff/9fb92e012cec/model/prov-dm.html
 *   Original author's acknowledgement:

[edit<http://www.w3.org/2011/prov/wiki/index.php?title=ResponsesToPublicComments&action=edit&section=37>]