Concerning methodology: (01)
> In a frame system, a slot simply means there's a relation that
> may be provided between an instance of the class on which it is
> defined, and its filler. In a first order logic system, the
> relation means exactly what is specified by its associated axioms.
> If you want to do the
> axioms first, that renders the Protege modelling step irrelevant. (02)
If one wants to first use Protege only to define a tentative
class hierarchy, that would be OK as a first step. But as soon
as we start to add properties and relations, I think it is
important to define the relations carefully. Axioms as
used in SUMO are fine. We just have to agree on which
ones to use. I think that the axioms should be included
as soon as a relation is asserted between classes (or
instances of classes).
A macro predicate feature is not **needed** to define the
axiomatic meanings of predicates (neither is Protege or
the SUMO browser). It is **convenient** and perspicuous for
cases where similar predicates are used to specify the meanings
of multiple relations. I think that anything that simplifies the
tasks of creating and understanding a complex ontology should be
given careful consideration. The SUMO browser is valuable
for that reason, not because it is needed.
I am not fully familiar with SUMO, but I do not recall seeing
a mechanism for specifying probabilistic relations. How are they
represented? (03)
I will be out of contact now for a week. (04)
Pat (05)
=============================================
Patrick Cassidy (06)
MICRA, Inc. || (908) 561-3416
735 Belvidere Ave. || (908) 668-5252 (if no answer)
Plainfield, NJ 07062-2054 || (908) 668-5904 (fax) (07)
internet: cassidy@xxxxxxxxx
============================================= (08)
============================================= (09)
Adam Pease wrote:
> Pat,
> I'm not really sure what you're asking, nor am I clear on why Cyc's
> macro features are relevant. They're certainly not needed for a precise
> axiomatic definition of terms.
> In a frame system, a slot simply means there's a relation that may be
> provided between an instance of the class on which it is defined, and
> its filler. In a first order logic system, the relation means exactly
> what is specified by its associated axioms. If you want to do the
> axioms first, that renders the Protege modelling step irrelevant.
> I should also mention that the precise semantics of the general notion
> of a Relation is already carefully and axiomatically defined in SUMO.
> Look at
>
><http://ontology.teknowledge.com:8080/rsigma/SKB.jsp?req=SC&name=Relation&skb=SUMO>
>
>
>
> Adam
>
> At 10:17 PM 4/17/2003 -0400, Patrick Cassidy wrote:
>
>> I have a suggestion about what I think needs to be done
>> even before we get to Adam's step 1, creating an
>> ontology in protege. Specifically, we need to
>> decide how to specify what the relations between
>> the classes (slots in Protege, predicates in SUMO)
>> are intended to mean. The meaning of the predicate,
>> for example (hasPart Automobile Engine) would need
>> to be specified by axioms unless there is a default
>> interpretation of such predicates.
>> Cyc has one mechanism to simplify the applications
>> of axiomatic rules, the RuleMacroPredicate. For
>> the "part" predicate, one might use the RuleMacroPredicate
>> "relationAllExists", and apply it thus:
>> (relationAllExists hasPart Automobile Engine)
>> This would mean that for every instance of an Automobile
>> there has to be at least one object of class Engine.
>> There would have to be additional constraints, such as
>> that the Part must be smaller than the whole object.
>> We also have to decide whether, e.g. an automobile is still
>> an automobile if the engine has been removed for repair --
>> i.e. can we say we have an 'Automobile" if it is
>> disassembled? We also need to decide how to indicate
>> that some objects have optional parts (chrome trim?),
>> and I would like to have a mechanism for indicating
>> probabilities of relations (this gets into encyclopedic
>> knowledge, but we at least need the mechanism even if it
>> is not often used in the earliest stages).
>> I interpret Adam's suggested methodology to mean that
>> we can get into such details later, in stage 2, but
>> I think that they should be tackled at the earliest stage,
>> since the relations are central to the interpretation of
>> he meanings of the classes. We don't need to get into
>> philosophical dialogues, but we do need some firm
>> criteria for deciding whether we do or don't have an
>> automobile in our garage at any given time.
>> I will be away for the next week and will check
>> back when I return.
>>
>> Pat
>> ========================================
>>
>> (010)
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