Re: Workflow Example in Formal Model HTML document

Hi Satya,

I missed the beginning and end of the teleconference Monday, but I wanted to say that my interpretation of provenance containers (and accounts etc., which seem related) has been that entities are intended to denote "things in the world", while provenance containers (and accounts) are syntactic things that don't necessarily denote real-world things, need not be changeable over time, but instead are used in the syntax of the model to organize data.  By analogy, in mathematics we can talk about "the set of all people whose first initial is Z" without there necessarily being a real-world thing corresponding to this set.

I haven't tried making this explicit in the formal semantics yet since I wanted to get the basic stuff right first.

One could certainly (if one wanted to) *introduce* an entity that stands for a particular provenance container, say a physical envelope that contains pieces of paper with provenance assertions written on them, and use annotations (or some other way) to relate the entity with the container and relate  the pieces of paper to other entities and to their corresponding data model instances.  Or, one could introduce a subclass of Entity called ContainerEntity, that represents real-world things that can contain things (including things that carry provenance information).  This would be a separate concept from how I understood ProvenanceContainer.

Your suggestion that any ProvenanceContainer is an Entity seems to me to impose an unnecessary level of meta-ness - I think we need to distinguish between syntax and semantics carefully here.

--James

On Sep 29, 2011, at 3:10 AM, Satya Sahoo wrote:

> Hi Luc,
> We were not able to reach an agreement on how ProvenanceContainer is not a specialized type of Entity during our ontology call on Monday due to time constraints. 
> 
> To help better understand the differences and similarities, I copied the two definition from PROV-DM to two documents and tried to compare them side-by-side. The following are the two definitions:
> 
> ===Entity====
> In PROV-DM, an entity expression is a representation of an identifiable characterized thing.
> 
> ===ProvenanceContainer===
> A provenance container is a house-keeping construct of PROV-DM, also capable of bundling PROV-DM expressions. A provenance container is not an expression, but can be exploited to return all the provenance assertions in response to a request for the provenance of something ([PROV-PAQ]).
> 
> According to the two definitions, a provenance container can be an "identifiable characterized thing" (not being an expression is not a conceptual constraint). Also, the ability to return all provenance assertions in response can be applied to an Agent also - similar to a software agent returning the current stock market quotes. 
> 
> Further, if an Entity "contains" provenance assertions it can still be an "identifiable characterized thing" thereby satisfying our current definition of Entity.
> 
> During our ontology telcon today Paolo explained that the primary difference between Entity and Provenance Container is that Provenance Container can "contain" provenance assertions while Entity are assumed not to contain assertions. But, this seems to be an application-specific requirement.
> 
> For example, for a person writing a 3-page letter the three pages will be instances of Entity and the envelope containing the three pages will be a container. But for the postal service personnel, who deal with thousands of envelopes per day, the envelope is an Entity (and a sack for transporting the envelopes will be a container).
> 
> Hence, I believe the difference between what thing is a ProvenanceContainer or an Entity is an application-specific perspective/requirement and there is no fundamental difference between the two terms - except that Provenance terms seems to be a specialized form an Entity in the sense that Provenance Container contains provenance assertions, while an Entity may or may not contain provenance assertions.
> 
> Paolo suggested that we should bring up this issue to the WG mailing list - hence I am cc'ing the mailing list also.
> 
> Thanks.
> 
> Best,
> Satya
> 
> 
> On Wed, Sep 28, 2011 at 3:58 AM, Luc Moreau <L.Moreau@ecs.soton.ac.uk> wrote:
> Hi,
> I thought we had already discussed this, but I see location as subtype of entity.
> Same issue as with provenance container.  This is not a subtype of entity.
> 
> 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  
> United Kingdom                     http://www.ecs.soton.ac.uk/~lavm
>