a question on semantics prov-sem and soundness of constraints (issue-630)

Hi James,

Here is a prov instance that is valid, I believe.

entity(e)
activity(a1)
activity(a2)
wasGeneratedBy(gen1; e, a1, 2011-11-16T16:05:00)
wasGeneratedBy(gen2; e, a2, 2012-11-16T16:05:00) //different date


Indeed, prov-constraints now allows multiple generations for a given entity.

There is a requirement that:
gen1 <= gen2 and gen2 <= gen1

But there is no requirement that 2011-11-16T16:05:00 and 
2012-11-16T16:05:00 be equal.

However, formalism 29 of prov-sem seems to imply that
2011-11-16T16:05:00 ==  2012-11-16T16:05:00

The reason of this difference is that prov-sem maps all events to a time 
on a time line, and
compares time information, whereas prov-constraints does not.

If my reasoning is right, this would indicate that the constraints are 
not sound with respect
to this semantics. Thoughts?

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

Received on Thursday, 28 February 2013 11:36:10 UTC