On Wed, November 10, 2010 15:29, Alan Ruttenberg said:
> ... (01)
> *Any* semantic framework (including OWL) supports an unlimited number
> of alternative languages (by language I assume you mean concrete
> syntax). However, the effect of not privileging any particular syntax
> is that unless there are reliable translators between the different
> syntaxes there is an (uninteresting, but very real) barrier to
> integration. I haven't checked on CL, but IMO, it should have a
> normative syntax that is considered the one that projects should make
> sure they can produce, so as to remove the aforementioned barrier. (02)
> The main difference between OWL(DL) and CL (correct me if I am wrong)
> is that CL lets you say anything in FOL, while OWL let's you only say
> some things in FOL, and (at least one thing - property transitivity)
> that is in SOL. (03)
Note that transitivity can be expressed by a first order rule. (04)
> The main practical issue with using unrestricted CL is that there are
> few systems that can reason (in a predictable way) over it. (05)
Where is the problem here? An interlingua must be at least as powerful
as the languages between which it is used to translate. Although
knowledge bases which it is used to translate may not exercise all the
capabilities of the interlingua, the interlingua could use higher order
expressions. The systems which translate to and from the interlingua
would be designed to do just that, and not act as generic theorem
provers. (06)
If one system stores data that can not be expressed by a second system,
then the second system would not be able to request it, so that data
would not be available to it. If the queried system were less powerful
than the querying system, it might not be able to translate a query into
its internal language. If so, it could not answer the question. (07)
> One might
> consider it for communicating OWL, but then only some part of CL would
> be able to be used, and I don't know that authoring systems are such
> that they can helpful for users who want to do that. (08)
No authoring systems exist for OWL?!? (09)
> I'm also not sure
> what would be done about transitivity, which is SOL. (010)
Use a rule, e.g.
hasAncestor(?person1,?person2) ∧ hasAncestor(?person2,?person3)
⇒
hasAncestor(?person1,?person3) (011)
> In any case, at
> least for OWL, it would be a "nice to have", as we *do* have a
> normative syntax (RDF/XML) which one can and should depend on, as the
> lowest common denominator. (012)
> A problem I see with all the normative languages is that they don't
> support much in the way of syntactic abstraction - macros. (013)
An advantage of rule macro predicates is that the inference engine can
be designed to handle them efficiently in code. (014)
One language that DOES have these features is one that has not been used
for the Semantic Web because its native syntax is not RDF: CycL. CycL
not only could be used to express mappings among different ontologies,
but since it has its own massive ontology, hundreds of thousands of the
ontology terms would already be expressed in the language. (015)
The full Cyc inference engine would not be needed for this purpose,
countering the problem of slow logic computation. (016)
-- doug f (017)
> They would
> be much friendlier if they did, as then the formats themselves could
> carry around the necessary machinery to translate from alternative
> syntaxes to common syntax. I tried to advocate for that to be included
> in the OWL spec, but didn't succeed.
>
> Best,
> Alan (018)
=============================================================
doug foxvog doug@xxxxxxxxxx http://ProgressiveAustin.org (019)
"I speak as an American to the leaders of my own nation. The great
initiative in this war is ours. The initiative to stop it must be ours."
- Dr. Martin Luther King Jr.
============================================================= (020)
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