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RE: Proposals to vote on related to 'event': deadline Dec 14th midnight GMT

From: Myers, Jim <MYERSJ4@rpi.edu>
Date: Wed, 14 Dec 2011 14:03:13 +0000
To: "public-prov-wg@w3.org" <public-prov-wg@w3.org>
Message-ID: <3131E7DF4CD2D94287870F5A931EFC2302A18F29@EX14MB2.win.rpi.edu>
+1 for 1
+1 for 2
Suggest 'milestone' to replace event - I think one challenge we have with the current nomenclature (activities and events) and action is that we're choosing synonyms for process instance which is making us think that we have two type of process instances that we're documenting in the provenance. I think the case is really that we have one type of process instance (activity) and some 'artificial' boundaries within those activities (not another set of shorter activities we need to find a name for). "Milestone" has that sense of being an artificial boundary - a line that is crossed - rather than a really short/instantaneous happening, and so might be a useful alternative.


From: Paolo Missier [mailto:Paolo.Missier@ncl.ac.uk]
Sent: Wednesday, December 14, 2011 7:39 AM
To: public-prov-wg@w3.org
Subject: Re: Proposals to vote on related to 'event': deadline Dec 14th midnight GMT

consistent with previous internal discussions:

+1 for 1
+1 for 2
0 for 3


On 12/14/11 12:16 PM, Luc Moreau wrote:
Dear all,
Thanks to those who have already voted.
This email acts as a reminder.

On 12/09/2011 06:36 PM, Luc Moreau wrote:
Dear all,

Several of you, including Satya, Tim and Jim have raised various
concerns about events.  Here are some proposals to tackle these
concerns in prov-dm WD3. Can you express your support in the usual
way, we will confirm the outcome at the next teleconference.


1. The concept of event as defined in prov-dm is instantaneous. On the
   other hand, other ontologies define the concept of event, e.g. LODE
   [1], as not instantaneous. This causes confusion, and risks
   hampering adoption.

2. The prov-dm document (WD2) is defining 'generation' in a
   conflicting manner.  On the one hand, in [2], it states that
   generation is an event, so is instantaneous.  On the other hand, in
   [3], it states that completion of generation is the event.

In a generation, what we care about is the point at which the entity
becomes available for consumption by others.  Before that, it's not an
entity yet (or it is not this entity being generated).  So, calling
the whole of generation an event (forget the choice of word for now)
is not what was intended.  The event is the point at which generation
is complete.

This is actually nice reflected in Olaf and Jun's provenance
vocabulary [4], where they have a similar concept, called Data
Creation defined as:

    DataCreation is a class that represents the completed creation of a data item.

Note the choice of word *completed*.


We therefore propose to change the definition of Generation [2] as
- With proposals 1 and 2, resolve the conflicting definitions around generation (and use) in prov-dm.
- With proposal 3, adopt another name for event.

PROPOSAL 1. Adopt the following Definition for generation.
In PROV-DM, a generation record is a representation of a
world event, the completed creation of a new entity by an
activity. This entity did not exist before this event; this entity is
available for usage after this event.

Comment: With this, we are not saying that creation of an entity is
the event, it's the completed creation that is an event.  It's also
also fine, I believe, to regard this as instantaneous.  Also, if
somebody wants to model the actual creation, it is also fine, they can
use activities for that.

For usage, we would take a similar approach. In the provenance
vocabulary, they use the completed access to a data structure, but
this is not right for what we want. Instead:

PROPOSAL 2. Adopt the following Definition for usage.
In PROV-DM, a usage record is a representation of a world
event: the start of an entity consumption by an activity. Before this
event, this entity was not consumed or used in any form or shape by
the activity, totally or partially.

Comment: These definitions are now exactly in line with those in [3].

PROPOSAL 3. Replace the word event by action.

Comment: So, prov-dm would define four actions: entity
generation/entity usage/activity start/activity end, which are all
instantaneous.  These actions would have "effects" on the system in
the sense that they change the entities and activities it contains.

Assuming proposal 3 is adopted, obviously, the text of proposals 1 and
2 would use the word 'action'.

Can you express your support, or counter-proposals, by Wednesday midnight GMT.
Assuming there is support, we would incorporate all these changes before XMas.

Best regards,


[1] http://linkedevents.org/ontology/
[2] http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#dfn-Generation
[3] http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#types-of-events
[4] http://trdf.sourceforge.net/provenance/ns.html#sec-DataCreationClasses


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<http://www.ecs.soton.ac.uk/%7Elavm>


-----------  ~oo~  --------------

Paolo Missier - Paolo.Missier@newcastle.ac.uk<mailto:Paolo.Missier@newcastle.ac.uk>, pmissier@acm.org<mailto:pmissier@acm.org>

School of Computing Science, Newcastle University,  UK

Received on Wednesday, 14 December 2011 14:06:29 UTC

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