On Feb 18, 2009, at 11:11 PM, John F. Sowa wrote: (01)
> Randall, Mitch, and Ian,
>
> In 1984, Cyc started with a simple frame-like notation,
> which was comparable in expressive power to OWL. But
> over the years, they found the need to keep expanding
> that language until it became CycL. Since the 1990s,
> CycL has supported full FOL, quantification over relations,
> and metalevel statements about the representation.
>
> During the development of the Common Logic standard,
> Lenat had been asking for the kinds of extensions to CL
> that were added to IKRIS. (02)
Actually the pressure came mostly from the Stanford IKL laboratory,
who were completely sold on the idea of context logics, influenced by
John McCarthy. The Cyc participants in IKRIS were quite happy to
translate their contexts into classical FOL if necessary. (03)
> In conceptual graphs, those
> features are called 'contexts', which have been an
> integral feature of CGs since the 1984 book. (04)
IKL (the IKRIS extension) doesn't add contexts to the logic, but
rather adds proposition names. These can then be used to emulate
context reasoning in a non-contextual logic. (05)
> Finally,
> in 2006, several participants from Cyc worked with us
> to develop the IKRIS extensions to CL. Those features
> support both CycL and the CG contexts.
>
> OWL was designed to have a very limited expressivity.
> It doesn't support if-then rules, it doesn't support
> full FOL, it doesn't support contexts, it doesn't
> support metalanguage, etc, etc. (06)
BUt its reasoners can run very fast and are guaranteed to be
decideable, which is the reason for accepting the limitations. That at
any rate is the official line. (This all refers to OWL-DL, not OWL-
Full.)
>
> The design goal for Common Logic, conceptual graphs,
> IKRIS, and other rich logics was to define a highly
> expressive language, which could be subsetted for
> special purposes. The advantage of this approach is
> that a single semantics (model theory) can be used
> for the entire family, and every member of the family
> is guaranteed to be compatible with every other.
>
> The W3C adopted the opposite strategy of developing
> a collection of multiple independent representations,
> such as RDF, RDFS, OWL 1 and 2, SPARQL, various rule
> languages, etc. But they raise the question of how
> each of those languages is related to the others and
> to a wide variety of other kinds of logic.
>
> My recommendation is to adopt a single, very general
> semantic representation and to relate the multiple
> specialized languages to the common semantics. (07)
I agree. But this is not a popular strategy. (08)
> Right
> now, the best candidate is CL or the IKRIS superset. (09)
Which is called IKL and is described here, for those who are interested: (010)
http://www.ihmc.us/users/phayes/IKL/GUIDE/GUIDE.html (011)
Pat (012)
>
> People can continue to use specialized languages,
> such as OWL, if they prefer. But they can't use that
> subset to support the full ontology. They'll have
> to move to other languages in the W3C collection or
> to invent their own.
>
> John
>
>
> _________________________________________________________________
> Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
> Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
> Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
> Shared Files: http://ontolog.cim3.net/file/
> Community Wiki: http://ontolog.cim3.net/wiki/
> To join: http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J
> To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx
>
>
> (013)
------------------------------------------------------------
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
Pensacola (850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes (014)
_________________________________________________________________
Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/
To join: http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx (015)
|