The reference mechanism has some merit, but very limited. It's useful
if the referenced concepts are very well and unambiguously defined, and
those who use it read and understand the documentation properly. (01)
But:
(1) Two different ontologists may mean exactly the same thing and
point to two different URI's - which may or may not be
intended to mean the same thing -- but the relation of the
two concept will be indeterminate.
(2) two different ontologists may interpret a URI differently and
point to it
though they mean different things -- this can easily happen with
the
very poor documentation typical of on-line knowledge
classifications
(3) in an ontology, there may be a pointer to a URI in some online
ontology for
concept A, and a pointer to a URI in another ontology for concept
B,
and in the referring ontology, concept B may be defined as a
subclass of
concept A, though in reality the original B and A may have little
in common. (02)
The act of referring to some URI will only be as useful as the
definition
attached to that URI is unambiguous. Ambiguity abounds, and
indeterminacy of
the relations of concepts in different ontologies is very high. When
we think that concepts are clear, it may just be because we are
disambiguating in context in a way that no machine can do with
existing programs. (03)
A common foundation ontology ('upper ontology' is a misleading
metaphor,
causing much misconception and grief) is the easiest way to achieve the
interoperability
we all think is desirable. But . . . (04)
Winston Churchill once remarked that "You can always count on
Americans to do the
right thing -- after they have tried all the alternatives." (05)
Alas, it seems that ontologists are proving him right once again. (06)
Pat (07)
-----Original Message-----
From: cuo-wg-bounces@xxxxxxxxxxxxxx
[mailto:cuo-wg-bounces@xxxxxxxxxxxxxx] On Behalf Of Schoening, James R
C-E LCMC CIO/G6
Sent: Monday, February 05, 2007 7:23 AM
To: cuo-wg@xxxxxxxxxxxxxx
Subject: [cuo-wg] The next key question (08)
CDSI WG, (09)
Given Pat Hayes' description (below) of what Jim Hendler refers
to as "URI-based reference mechanism
coupled with the standard for KR and other aspects is
aimed exactly at scalability.": (010)
The key question now is: Could the above referenced technology
(when it matures) be used to achieve semantic interoperability across
large numbers of domains (with independently developed ontologies)?
Any takers? (011)
Jim Schoening (012)
Pat Hayes wrote:
>
> OK, here's my take on that.
>
> First, "standard for KR". I think all that Jim means is, the SWeb is
> intended to use whatever is the best available KR mechanism that can
> be adopted as a 'standard', ie which a wide enough spectrum of users
> can be persuaded to agree to use. No such choice will be free from
> controversy. OWL wasn't and isn't free from controversy, and nobody
> even knows if a large enough community can ever be brought to
> consensus on an acceptable Rule language. But assuming that some WG
> can get its job completed, and produces a useful notation, then that
> can be used on the SWeb. There are plenty of potential candidates
> which are way more expressive than OWL readily available. So it would (013)
> be a mistake to identify the SWeb vision with OWL or DL technology in (014)
> particular. OWL-DL is just the first in what one hopes will be an
> evolving series of KR standards which will provide the infrastructure (015)
> of the SWeb. Perhaps the next one will be more like
> Python+Prolog on steroids. Or it may be a
> breakthrough in CL reasoners using the guarded fragment, who knows?
> The decision is as much political as technical, or even subject to
> whims of intellectual fashion.
>
> "URI-based reference mechanism" is more interesting. This is one of
> the few things that really is new and different about the SWeb: it is (016)
> part of the Web, and subject to Web conventions and protocols. It
> isn't *just* applied ontology engineering. So, every SWeb ontology is (017)
> required to use names drawn from a (literally) global set of names.
> The scope of these names is the entire Web. There are no 'locally
> scoped' or 'private'
> names on the Sweb. So if your ontology uses a name for a concept, my
> ontology can use it too.
> Anyone can 'say' anything about everyone else's concepts, on the
Sweb.
> This is a whole new game, which nobody has played before. A can
> introduce a concept called A:thingie1 and B can introduce B:thingie2, (018)
> and C can then, entirely independently and without asking for A or
B's
> permission, assert that (say) A:thingie1 is the same as B:thingie2. A (019)
> and B may disagree: tough tittie, they can't stop C from making the
> assertion. C can say things about A's ontology, in fact, such as
> assert that it is all BS. The globality of the namespace has a whole
> range of consequences which we are only beginning to explore. And
> being URIs (actually IRIs these
> days) , these names can also be used as identifiers which *access*
> things on the Web.
> Whether these accessed things should be the referents of the names is (020)
> currently controversial (I think not, in general), but that they
> access
> *something* is not even remotely at issue. So SWeb concept names have (021)
> a whole new dimensionality to them, which is (or at any rate can be)
> orthogonal to their use as referring names. In particular, it allows
> ontologies to "address" other ontologies (a pale version of which is
> the OWL:imports primitive, but one can do a lot more than this),
which
> obviously has many potential applications relevant to scaling.
>
> Hope this helps.
>
> BTW, I entirely agree with Jim's optimism. I think people are way too (022)
> scared of inconsistencies. Lets wait and see what problems actually
> crop up before trying to solve or avoid ones that we only worry about (023)
> rather than actually find.
>
> Pat
> (024)
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