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PROV-ISSUE-203: Proposal to amend definition and usage of Plan in PROV-DM [prov-dm]

From: Provenance Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Thu, 15 Dec 2011 19:52:04 +0000
To: public-prov-wg@w3.org
Message-Id: <E1RbHLY-0002DE-Qr@tibor.w3.org>

PROV-ISSUE-203: Proposal to amend definition and usage of Plan in PROV-DM [prov-dm]

http://www.w3.org/2011/prov/track/issues/203

Raised by: Stephan Zednik
On product: prov-dm

Dear all,

I would like to suggest an amended definition and usage for plan in PROV-DM.

CONTEXT:

1. The concept of plan is currently related to activity via a plan link, which is a specialization of an activity association record; as a consequence all plans are agents.

http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#record-planLink

2. This means that according to the definition of agent at http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#section-entity-activity-agent, plans 1) take an active role in an activity and 2) can be assigned some degree of responsibility for the activity taking place.

3. The relation between agents and the plan that guides their actions is not explicit in PROV-DM.  We could infer that all agents involved in an activity act according to the activity's linked plan, but this prevents us from describing an activity were multiple agents act guided by different plans.

PROPOSAL 1: Amend the definition of plan in PROV-DM to:

"In the context of PROV-DM, a plan should be understood as the description of a set of actions or steps intended by one or more agents to achieve some goal."

PROPOSAL 2: Amend plan link record such that it is not a specialization of an activity association record.

Comment: I do not think we should define all plans as agents.  By our existing definition a plan is a "set of actions or steps ... to achieve some goal."  It is a description (usually in the form of a document) of the action or actions an agent should take to achieve a desired goal.

As a description of the actions an agent should take, it does not make sense for a plan to have responsibility.  The responsible party for a plan (e.g. owner, creator) could have some responsibility for the outcome of the activity, but the description of the "set of actions or steps intended to achieve some goal" would not.

A plan without an agent is (generally) inert.  Something must follow/execute the plan for there to be action.  A recipe is inert - bread is made by the baker.  Driving directions are inert, a driver must control the vehicle from the trip's point of origin to its destination.  If driving directions are incorrect, it would be the source of the driving directions (e.g. Google Maps) that would bear responsibility for the failure of the activity to result in the desired objective.

Software and especially workflows are a fuzzy area; you can reasonably define any software as a document of steps that a microprocessor is capable of executing.  

To allow users to record provenance in a way that is natural to them I suggest we not define plans and agents as disjoint, but I do not think we should define all plans as agents.

PROPOSAL 3: Amend plan link record such that it can express which agents in the activity are following the plan.

PROPOSAL 4: We should define a relation to describe the responsible party for a plan.

--Stephan
Received on Thursday, 15 December 2011 19:52:06 UTC

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