Re: SUO: ontology as science
Pierre,
I'll just focus on the central point of your note:
PG> ... It has also been said that Cyc is using only one
> upper-level ontology.
Yes, there are no options in the topmost level. I believe
that even that level should have options.
In an earlier note, I sent some slides that I used to
report on the Cyc review meeting last week. Following are
some slides from the end of that list, in which I make some
comments about the need for options at a higher level.
This single example is by no means a definitive analysis
of the issue, but it illustrates the general direction,
about which I'll have more to say later.
John
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SUPPORTING MULTIPLE ONTOLOGIES
* Cyc supports microtheories, which are subontologies that
may be inconsistent with one another.
* Example: microtheories about vampires or Greek mythology.
* Cyc currently has 6,000 microtheories.
* Cyc can create new microtheories dynamically to represent
modalities or some agent's knowledge and belief.
* But there is a need for different microtheories even at the
upper levels of the ontology.
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EXAMPLE FROM CYC
A sample story used by the Cyc ontologists:
Jim, a car dealer, saw a tornado approaching the lot where
all his cars were located. Shortly thereafter, the tornado
swept through the lot and destroyed all his cars.
Implications of the Cyc ontology:
* If a tornado approaches, it is an object.
* If a tornado destroys something, it is an event.
* But objects and events are disjoint.
* Therefore, there must be two distinct entities:
TornadoAsObject and TornadoAsEvent.
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PRECISION AND VAGUENESS
Precision is sometimes bad:
* Essential for computability and logical deduction.
* But highly inflexible: an advantage in some cases, but
a disadvantage in other cases.
* A precise ontology may force undesirable choices.
Vagueness is sometimes good:
* Inevitable starting point for planning, design, research,
and any kind of sincere negotiation.
* Some things -- such as tornadoes, glaciers, and clouds --
may be both objects and events.
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CYC INTERMEDIATE LANGUAGE (I-CYCL)
* I-CycL uses the same syntax and logical operators as CycL.
* But I-CycL uses concept types that map directly to the words
of natural languages.
* The concept type Tornado, for example, could be used in I-CycL.
* But in the mapping from I-CycL to CycL, the constraints
imposed by the Cyc ontology would replace Tornado with
either TornadoAsObject or TornadoAsEvent.
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MAPPING LANGUAGE TO LOGIC
The I-CycL approach has also been used with other logic-based
languages, including conceptual graphs:
1. The first stage of mapping language to logic uses labels taken
from lexical resources, such as WordNet and FrameNet.
2. Usually, there is a one-to-many mapping from the lexical labels
to the names of the concept types and relations in the ontology.
3. The selection of specific concept types and relations depends
on constraints derived from axioms and definitions in the ontology.