PROV-ISSUE-8: defining generation in terms of `IVPT of'

Hi all,

A first attempt to define Generation in terms of IVPT ... OF A THING, as 
Jim mentioned
earlier, in a separate thread.

I think that process execution creates/modifies a THING ... and this 
results in a *new* IVPT of that thing.

Here it is:

/
Generation is the act by which a process execution creates or changes a 
thing, resulting in a new IVPT of that thing.

Generation is associated with a time (the time at which the new IVPT 
begins its existence), though statements about generation do not have to 
mention time./


Some comments:
- if a new thing is created, it is clear that we have a new IVPT of that 
thing
- if the thing is modified, then it is a requirement that a new view 
(IVPT) is generated ...
        otherwise, it would still be a view that existed before
- if the process execution was taking a long time to modify/create the 
thing, there is only one
    instant at which the (invariant!) IVPT appears
- I think this captures well a stateful objects, where processes can 
modify the object, resulting in
    different IVPTs corresponding to the various states

What do you think?

http://www.w3.org/2011/prov/wiki/ConceptGeneration#Definition_of_Generation_by_Luc

Cheers,
Luc