Randall, Mitch, and Ian, (01)
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. (02)
During the development of the Common Logic standard,
Lenat had been asking for the kinds of extensions to CL
that were added to IKRIS. In conceptual graphs, those
features are called 'contexts', which have been an
integral feature of CGs since the 1984 book. 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. (03)
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. (04)
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. (05)
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. (06)
My recommendation is to adopt a single, very general
semantic representation and to relate the multiple
specialized languages to the common semantics. Right
now, the best candidate is CL or the IKRIS superset. (07)
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. (08)
John (09)
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