Re: SUO: OpenCyc Motion Open for Discussions
Hi Randall,
On Thu, 10 Apr 2003, Randall R Schulz wrote:
> >The Cyc microtheories are organized into a partial ordering via
> >implies, which is how you were describing the lattice of theories in
> >your message to Radu.
>
> "Implies?" Do you mean material implication? What exactly does this
> mean? That (#$genlMt #$lower #$upper) says that the conjunction of the
> formulas in #$lower implies the conjunction of those in #$upper? That
> the conjunction of the formulas in #$lower implies the disjunction of
> those in #$upper (as if #$genlMt was a sequent: #$lower |- #$upper)?
> One of these in the opposite direction, from #$upper to #$lower? None
> of these seems sensible to me.
>
> I really don't get how #$genlMt is associated with implication. Could
> you explain?
If (genltMt SPEC GENL), then from SPEC Cyc can see (i.e. know about,
use in inference) all of the assertions in GENL, *as well as* whatever
assertions are explicitly made in SPEC. It is as though the assertions in
GENL (both those made explicitly and those which it in turn inherits from
its genlMts) Are virtually asserted in SPEC, thus making it true in some
(yes, maybe virtual) sense that SPEC implies GENL but not vice versa.
> (Maybe if we iterate this process enough, I'll get my answer to "what
> are the semantics of CycL?" question.)
This question was actually discussed some last year if I recall. Bill
Anderson pointed out then that crafting a formal semantics for CycL is
non-trivial given that the inference engine implements resource
constraints (e.g. number of backchains, time-cutoffs etc.) These have
recently become even more sophisticated due to a new inference harness.
If one wants to ascertain the semantics of any given constant, however,
one looks at the #$comment (often quite extensive for core constants), and
the rules asserted on it. And also *uses* it, and sees what it can do.
Regards,
Cathy.
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Cathy Legg, Phd Cycorp, Inc.
Ontologist 3721 Executive Center Dr., ste 100
www.cyc.com Austin, TX 78731-1615
download OpenCyc at http://www.opencyc.org
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