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Re: [ontolog-forum] Architectural considerations in Ontology Development

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "doug foxvog" <doug@xxxxxxxxxx>
Date: Tue, 19 Feb 2013 16:33:36 -0500
Message-id: <56c022a2404afbaa0b38897e036111ca.squirrel@xxxxxxxxxxxxxxxxx>
On Sat, February 16, 2013 17:44, Matthew West wrote:
> John Sowa wrote:
> ...
>> MW
>> > CYC is not an integrating ontology - granted it is very large, but it
>> > has an entirely different purpose.
>>
>> I agree that Cyc was primarily designed to be a descriptive ontology,
>> but it
>> can also support microtheories of normative concepts for any purpose
>> anyone might need to specify.    (01)

>> For example, Cyc can give underspecified definitions for time and space
>> that avoid any commitment to a 4D or a 3+1 D ontology.  Then different
>> microtheories could add axioms that complete the spec in one way or the
>> other.    (02)

> MW: Yes, but can it translate between them?    (03)

Yes.  Cyc includes both models & can translate between them.    (04)

> MW: Unless you have the means to
> bring different ways of describing the same thing into a single
> representation, you cannot bring together data from different sources.    (05)

Agreed.    (06)

> MW: On the contrary, for an integrating ontology, you only want one way to
> say something, but you want it to be the most expressive way of saying it,
> so that any other way can be expressed that way.    (07)

If the integrating ontology has only one way to say something, then how
could it translate from a way it can't express to a way that it can?  This
statement and the previous one seem to be in contradiction.    (08)

And is there a need for defining "the most expressive way"?  Are we now
back to the philosophical arguments that have been going on for millennia?
For normal applications, is 4D more or less expressive than 3D+1?  Is
quantized time/space more or less expressive than continuous?    (09)

>> JFS
>> >> Avoid making detailed commitments in the top levels.  Push any
>> >> complex details or distinctions into the middle and lower levels.    (010)

>> I believe that it is possible to
>> communicate between systems that use different and even inconsistent
>> ontologies or no explicit ontology of any kind.
>
> MW: Of course it is POSSIBLE, but it is also UNNECESSARILY
> EXPENSIVE unless
> you only have 2 or 3 ontologies to ingtegrate, or you use an integrating
> ontology to mediate between them.    (011)

Isn't the discussion about an integrating ontology?
Isn't it unnecessarily expensive, if you have a large number of ontologies
to integrate to not use an integrating ontology?    (012)

>> An underspecified descriptive ontology could be used for general
>> communication.  You could define your ontology as a stand-alone
>> normative
>> ontology.  But for broader communication, a copy of it could be inserted
>> as a microtheory underneath a descriptive ontology.    (013)

> MW: That does not help.    (014)

Why not?  It enables communication.    (015)

>> Communications between the systems are possible if the messages
>> do not require any of the details that cause conflicts.    (016)

> MW: That is even worse. You have to be able to translate between
> conflicting representations,
> and bring the results into one environment, or you have not
> actually managed to integrate anything.    (017)

Stating that the messages "do not require" certain details does not mean
that they "do not allow" certain details.  So long as they are allowed and
are stated in the source system, then the messages encoded in the
integrating ontology can encode and translate them.    (018)

So you get your integration.    (019)

>> ...
>> I agree that an ontology used *only* for normative purposes
>> can put design decisions (such as a 4D vs 3+1 D ontology)
>> at the highest levels.    (020)

Agreed.  But i would want to see what specification requirements
made such a decision normative.  As an ontological architect, i
might take up such a decision with the specification writers if
it actually existed.  If the decision did not affect the system using
the ontology, i would recommend against it as an extraneous
constraint.  If it were a decision used at the implementation
level or the application level, i would push that decision down to
the set of systems that required it.    (021)

>>  But to support communication with outside systems
>> (and interoperability depends critically on communication),
>> it is necessary to use a very underspecified upper level.    (022)

> MW: It should not be underspecified.    (023)

The reference is to underspecification at the upper level.    (024)

> To under specify would risk poor mapping into the ontology,
> the rules you define would prevent this. Poor
> data quality would result.    (025)

Underspecification of terms in the ONTOLOGY does NOT mean
underspecification of messages ENCODED in the ontology.  If
the MESSAGES are underspecified, then poor data quality results.    (026)

A big issue with poor data quality is that most data is contextual,
and the full context may not be communicated in messages that relay
some of the data.  The context usually includes a time, but sometimes
a time period.  The context may include a specific organization (employee
or customer list), geographic area limitation, set of accounts, etc.  For
technical data, the context might include type of measuring device used,
conditions under which the measurement was made, various uncertainty
parameters, etc.  For many tables, the context includes the units of
measurement.    (027)

If the context includes that time is discrete, or a physical object is
a space-time worm, that could be another context item encoded and
transmitted.  But i find it hard to visualize what kind of system would
care about such context parameters.  One that did, but used the opposite
choice from that of the sending system, could, AFAIK, select the other
choice with no impairment of the data.    (028)

If someone can demonstrate that this would be a problem, please
provide an example data statement in which such a translation
would yield data that would be unacceptable to a system that had
made the other choice.    (029)

> As I said before, it should be correctly
> specified with axioms appearing at the right level, neither higher nor
> lower than they properly belong.    (030)

Agreed.    (031)

>> In summary, your normative ontology could be used with a descriptive
>> ontology such as Cyc by defining it as a Cyc microtheory in which the
>> underspecified terms in the upper level would become fully specified
>> in the way that your ontology requires.    (032)

> MW: No. What you would need is a mapping between Cyc and your
> integrating ontology so that different microtheories that covered
> the same area of the integrating ontology were mapped to the same
> place in the integrating ontology.    (033)

Somehow, i can't understand what you mean here.    (034)

What is a "place in the integrating ontology"?    (035)

I have understood that the "mapping" that we have been discussing
to include two things:
* the mapping of terms of one ontology to terms of the other ontology
* the mapping of statements in one ontology to statements in the other
   ontology, which mapping is informed by the inter-term mapping    (036)

John was stating that a normative ontology which selected some
metaphysical positions could inherit from agnostic ontologies (e.g.,
encoded in Cyc microtheories) and have those metaphysical positions
as additional axioms.  This could be done by having microtheories for
the various metaphysical positions and have the normative ontology
inherit from the selected metaphysical microtheory as well as the
agnostic one.  There would be no need to explicitly state the
metaphysical rules in the domain microtheory -- they would be stated
once in their own microtheory and those microtheories which chose
to commit to them could merely inherit the metaphysical microtheory.    (037)

The mapping among agnostic Cyc domain ontologies, ontologies for
various metaphysical positions, and domain ontologies with metaphysical
positions would be that such domain ontologies would inherit
from the agnostic domain ontologies and the generic metaphysical
ontologies.  In Cyc terms the inter-ontology relationship would be #$genlMt
(after term conversion).    (038)

> This would bring all the ground facts in Cyc into a form
> where they could be compared, and integrated with
> those from different sources.    (039)

It seems that that is what the Cyc microtheory system already provides.    (040)

Regards,
  doug foxvog    (041)

> Regards
>
> Matthew West
> Information  Junction
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