Re: formal semantics strawman

James,

Thanks.  This help to clarify for me some things that weren't clear to me in the 
model document.

You say at 
http://www.w3.org/2011/prov/wiki/FormalSemanticsStrawman#Interpreting_an_entity_assertion:
[[
Note that there is a design choice here: do we require that the entity 
associated with id be the same throughout the interval or not? I have chosen to 
require this, since otherwise the entity assertion doesn't seem to be about a 
"single entity across a time interval". Of course, if we require that the 
mapping from URIs to entities be time-invariant then this problem goes away.
]]

As far as I can tell from a quick skim, everything else works as intended (at 
least in sections 1.3, 1.4) if the URI->Entity mapping is invariant.  Which I 
think leads to a model in which the distinction between resource and entity 
(which I find to be unhelpful) becomes less significant.

#g
--

On 25/08/2011 18:13, James Cheney wrote:
> Hi,
>
> I've been promising for a while now to write down a short formal semantics strawman to illustrate what I have in mind.  I've put something onto the wiki here:
>
> http://www.w3.org/2011/prov/wiki/FormalSemanticsStrawman
>
> It's definitely not a finished product but I've made an effort to cover entity assertions, ivp/complement, process execution, and events (but NOT derivation :)
>
> One thing that's become apparent already is that there is a large potential for confusion since we are talking about assertions about things that may change over time.  The assertions may explicitly mention time points/intervals and they may also implicitly have "assertion time" or "time intended to be valid"  associated with them. Some of the assertions in the Conceptual Model document also have explicit times associated with them (e.g. use, generation and process execution assertions.)  Others such as entity assertions do not have explicit time arguments, but the discussion surrounding them refers to time points or intervals during which the entity being described exists.
>
> So for each kind of assertion p(x,y,z,...), it would be helpful to clarify whether:
> 1.  p(x,y,z,...) is something that either always holds or never holds; or
> 2.  p(x,y,z,...) can hold or not at a specific point in time t (there may be a convention that we can make this explicit by adding an argument, e.g. p(x,y,z,...,t)); or
> 3.  p(x,y,z,...) can hold or not during an interval [t1,t2] (again there may be a convention where we add 2 arguments).
>
> Currently, there seem to be a mix of conventions.
>
> Comments are welcome.  I'm not pretending to have read all the relevant background / mailing list discussion carefully and so I may be using terminology incorrectly.  As the name suggests, I expect this to be easy to knock down, but hope that we'll learn something in doing so anyway.
>
> --James

Received on Thursday, 25 August 2011 18:02:00 UTC