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PROV-ISSUE-343 (account-objections): Objections regarding Account [prov-dm-constraints]

From: Provenance Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Wed, 11 Apr 2012 14:27:07 +0000
Message-Id: <E1SHyVn-0003J5-0r@tibor.w3.org>
To: public-prov-wg@w3.org
PROV-ISSUE-343 (account-objections): Objections regarding Account [prov-dm-constraints]


Raised by: Timothy Lebo
On product: prov-dm-constraints

This issue serves as a place holder for a variety of issues regarding the account section of dm-constraints.


The underlying cause for this group of issues is that Accounts would not be permitted to span the "specialization hierarchy" like other entities can, similar to the "Different users may take different perspectives on a resource with a URL" example. One should have the freedom to apply perspectives to what an Account is, and the current definitions prevent that.

The following adjustments would help to address some of my concerns:

"An account is as a container of provenance descriptions, hence its content MAY change over time."
"An account is a bundle of provenance descriptions whose content MAY change over time."

"If an account's set of descriptions changes over time, it increases monotonically with time."
"If an account's set of descriptions changes over time, it SHOULD increase monotonically with time."

I cannot agree to the following:

"A given description of e.g. an entity in a given account, in terms of its identifier and attribute-value pairs, does not change over time."

nor the Notes:

The last point is important. It indicates that within an account:

    It is always possible to add new provenance descriptions, e.g. stating that a given entity was used by an activity, or derived from another. This is very much an open world assumption.
    It is not permitted to add new attributes to a given entity (a form of closed world assumption from the attributes point of view), though it is always permitted to create a new description for an entity, which is a "copy" of the original description extended with novel attributes (cf Example merge-with-rename). 

Being forced to "write only once" about an entity is too restrictive. The account maintainer should be aware of the characterization interval and respect it and know when they are talking about the same entity or when it's a slightly different entity that warrants a truly distinct entity. If the _same_ entity had an additional fixed attribute that was simply unknown at "first write", the maintainer should not be required to duplicate the original entity just to update their description.
Received on Wednesday, 11 April 2012 14:27:09 UTC

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