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Re: [ontolog-forum] Context, at last!

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Nicolas F Rouquette <nicolas.rouquette@xxxxxxxxxxxx>
Date: Mon, 20 Jun 2005 09:42:22 -0700
Message-id: <42B6F1EE.3000107@xxxxxxxxxxxx>
Chris Menzel wrote:    (01)

>>Also - an important consideration of context is perceiver.  
>Yes, that can be important.  That is one reason there is a lot of active
>research on formal theories of context at the moment.
>>To you and I, a coffee table is a solid item, to a neutrino, it is a
>>lot of open space interspersed with a few bits of solid matter...
>True enough, so a neutrino's ontology of your front room will probably
>look a lot different than your front room ontology!  Note, though, that
>the notion of context is often just assumed in the background of an
>ontology -- we often create ontologies *from the perspective of a given
>perceiver or set of perceivers*, e.g., domain experts in a mfg shop
>floor.  For these cases, the notion of context needn't play an explicit
>role.  More and more, though, we have a need to represent multiple
>ontologies arising out of different contexts within a *single*
>framework, and this requires explicit mechanisms that enable us to group
>pieces of information according to context -- and that's exactly what
>formal theories of context are attempting to provide.
Thanks again for taking great patience in explaining basic notions.
What does it mean to use a *single* framework for representing multiple 
according to different contexts or some other criteria? What is the role 
of the framework in this case?    (02)

Earlier, you mentioned that there's a lot of formal theory work in the 
field of "intensional logics".
Your (edited) explains this very clearly (at least to me).    (03)

Modal logic is a prime example of an intensional logic. Notably, 
"it is necessary that" is a non-truth-functional operator, that is, 
the truth value of a sentence of the form "It is necessary that p" 
is *not* a determinate function of the truth value of p 
(unlike, say "It is not the case that p").      (04)

Consider cases where p is, for example, "2+3=5" and "George Bush is president",
respecitvely.  Both propositions are true.  But in the one case "It is
necessary that p" is true and in the other it isn't.  So the necessity
operator is not truth-functional.
----------------    (05)

Now, suppose we wanted a single framework with which we can represent
multiple ontologies according to different contexts / perceivers.    (06)

Streching Duane's examples a bit, we might have:    (07)

- two ontologies about the same subject matter, i.e., the concept of a living 
 - neutrino ontology ( a bunch of empty space....)
 - couch potato ontology (somewhere to put a glass & a bowl of popcorn on top 
of)    (08)

What does having a single framework mean here?    (09)

We don't have a lot of insight into people's relationships with neutrinos;
therefore, the significance of a single framework for both ontologies
isn't obvious nor intuitive.     (010)

Let's pick two ontologies with intuitive connections between them, e.g.:    (011)

- two ontologies about the same subject matter, i.e., the concept of a living 
 - furniture store ontology (features - strength, texture, look, cleaning -, 
prices, building materials - wood, metal, cloth, ... -)
 - couch potato ontology (somewhere to put a glass & a bowl of popcorn on top 
of, stretch the feet on and kick the bowl in a moment of excitement)    (012)

Ok, so spills can happen, someone's going to be upset if the table gets a stain 
from the drink or the popcorn that won't go away
or if the heavy feet will break the table. These kinds of properties use both 
ontologies but in order to do so, it is necessary
to establish correspondences between their concepts & individuals.     (013)

What isn't clear to me is the following:    (014)

a) defining a precise semantics for terms used to talk about ontologies of 
something, e.g.
(i.e., classes & object properties in OWL)    (015)

- descriptions
- situations
- subject 
- point of view
- context
- frame of reference
- perspective
- framework
- representation
...    (016)

b) using different logics for reasoning about and computing with the properties 
and property values of indidividuals and concepts in the ontology
(i.e., data properties in OWL)    (017)

- logic of time (e.g., are all contexts defined w.r.t. the same clock or can we 
have 2 contexts defined w.r.t. 2 separate clocks)
- logic of space (e.g., something like newtonian physics - glass, popcorn, 
table, ... - vs. something like quantum physics - neutrino & other exotic 
particles -)    (018)

-- Nicolas.    (019)

>Chris Menzel
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>To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx
>    (020)

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