imports and commitment - troubled by today's call...

Sorry I could stay to end of phone call today -- there were a couple 
of things being discussed I'd like to have followed up on -- one in 
particular is bothering me

It has to do with imports vs. commitment to what something claims. 
Tim said that he viewed owl:imports as more or less a "#include" 
mechanism, and I agree.  However, if referring to a URI on another 
page is also like a "#include" then I think we break the Semantic Web 
-- that is, the "imports closure" of a SW document could conceivably 
end up being a major portion of the whole semantic web if we are 
successful and end up with lots of things pointing at each other 
(which is certainly my vision of the SW, and I think also Tim's)

I don't have a solution in mind yet, but I really want to be able to 
tease apart a few different situations:

1 - I think the NCI ontology (17000 classes) is great, and I want to 
let people coming to my documents know that my document concurs with 
it
    this can be handled by my saying me document owl:import NCI 
(although that might cause me to have to read in a whole lot of 
classes)

2 - I look at the NCI ontology and examine a small portion of it.  I 
think that part is good (the part on oncogenes), but I'm not sure 
about the whole document (which contains stuff about lifestyles, 
about fast food restarants, and lots of other things) -- I might like 
my document to say that I use certain terms from that document, but 
am not willing to "commit" to the others (I don't say I disagree with 
the others, just that I'm not willing to buy in)
    I haven't seen any mechanism to do this, although at one point 
Bijan suggested a mechanism in which the owl:ontology statement could 
include a set of URIs from that or other documents and give them a 
name together.  This was roundly rejected by Peter and Ian, among 
others, but I still think it had merit (esp in light of the 
discussion on this list)

3 - I'm looking for a way to mark up some instance data, and I have a 
database of information about genetic loci - I see that the NCI 
ontology has a list of these loci (MYC, PVT, etc) so in my document I 
define some properties of the nci:locus class and assert my 
information -- this seems valuable to me because I figure other 
people will decide if they like the NCI ontology, and if they do 
maybe they'll find my data and properties useful.  (This is a real 
situation we're trying to encourage some large genetic DB providers 
to buy into) - the user also may find some other cancer ontologies 
and define some properties on the terms from that as well..
     Difference in this case from 2 is that this user is trying to add 
their own information to be used with some ontology, and doesn't 
really care what is in the parent ontology other than some particular 
class they want to use - perhaps the same mechanism could be used as 
in 2, but might be a lot of extra work over just using a URI 
reference   (This is my personal favorite for what a URI reference 
without an imports statement should do)


In essence, I like Tim's idea of a protocol, and that somehow it is 
between the user and the definer of the URI, but I'm worried that if 
it becomes transitive (i.e. protocol gets B to understand A, gets C 
to understand B, gets D to understand C, ...) we cannot distinguish 
the cases above, or worse, we end up with an everything imports 
everything type situation (I recently created a version of part of 
the NCI ontology that includes a reference to something in CYC and to 
something in WordNet -- my document contains about 20 lines, but if 
you have to bring in all those things to "understand" it, you get 
well over a million triples -- this strikes me as a problem)


-- 
Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  *** 240-277-3388 (Cell)
http://www.cs.umd.edu/users/hendler      *** NOTE CHANGED CELL NUMBER ***

Received on Friday, 26 September 2003 17:05:30 UTC