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Linking Across Provenance Bundles - comments

From: Graham Klyne <GK@ninebynine.org>
Date: Thu, 29 Nov 2012 18:15:15 +0000
Message-ID: <50B7A633.6020508@ninebynine.org>
To: W3C provenance WG <public-prov-wg@w3.org>
http://dvcs.w3.org/hg/prov/raw-file/default/links/prov-links.html

My comments are focused on Section 2, Conceptual Definition of Mention

[[
An entity e1 may be mentioned in a bundle b, which contains some descriptions 
about this entity e1: how e1 was generated and used, which activities e1 is 
involved with, the agents e1 is attributed to, etc. Other bundles may contain 
other descriptions about the same entity e1. Some applications may want to 
augment the descriptions of entity e1 found in bundle b with other information. 
To this end, PROV allows a new entity e2 to be created and defined as a 
specialization of the preceding entity e1, and which presents at least an 
additional aspect: the bundle b containing some descriptions of e1. With this 
relation, applications that process e2 can know that the attributes of e2 may 
have been computed according to the descriptions of e1 in b.
]]

"Some applications may want to augment the descriptions of entity e1 found in 
bundle b with other information" appears to be in conflict with the earlier 
statement "Other bundles may contain other descriptions about the *same* entity" 
(my emphasis).

[[
The mention ◊ of an entity in a bundle (containing a description of this entity) 
is another entity that is a specialization of the former and that presents the 
bundle as a further additional aspect.

An entity is interpreted with respect to a bundle's description in a domain 
specific manner. The mention of this entity with respect to this bundle offers 
the opportunity to specialize it according to some domain-specific interpretation.
A mention of an entity in a bundle results in a specialization of this entity 
with extra fixed aspects, including the bundle that it is described in.
]]

I have two concerns here:

This definition leans heavily on the notion of "fixed aspects", but this term is 
not actually defined anywhere.

Philosophically, I have difficulties with the implication that simply by being 
mentioned in a bundle somehow changes the entity itself.  Suppose you are 
looking at an elephant, and writing down a description of that elephant.  Then I 
come along and look at the elephant from a different perspective, and write down 
a description of what I see.  We may put down different descriptions, but we are 
describing the *same* elephant. The fact of me doing that doesn't change the 
elephant in any way, nor does it affect the validity of your description 
concerning the elephant.  Yet the idea that an observation is a new "fixed 
aspect" seems to suggest that this is act of observation makes it a different 
elephant.  (Not allowing Heisenberg/observer effects here.)

What I think is missing from your description is some notion of the perspective 
("observation context") from which the descriptions in a bundle are derived.

So here's my attempt to try and capture something of this:

[[
Statements about an entity are based on information available from some 
perspective, and the extent of information available may be affected by the 
context of an observer that records it.  The mention construct provides a way to 
make additional statements about the entity from the same context or perspective 
as other statements in a bundle.  For example, one bundle may contain statements 
about a web page accessed from a network connection in USA which is presented 
containing comments authored by Americans, and another may contain statements 
about the same page accessed at the same time from China, which may contain a 
different set of comments.  Deducible provenance about the contributors to this 
page may thus vary based on where it is accessed from.

The mention construct provides a way to associate this additional contextual 
information with an entity, such as the location from which it has been accessed 
when making some provenance assertions.
]]

#g
--
Received on Thursday, 29 November 2012 18:16:17 GMT

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