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Re: [ontolog-forum] Foundation ontology, CYC, and Mapping

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Fri, 26 Feb 2010 16:09:58 -0500
Message-id: <4B8838A6.40506@xxxxxxxxxxx>
Pat,    (01)

Just one point:    (02)

PC> I do question that users of an ontology will *want* the meanings
 > of their already-defined ontology elements to change as new elements
 > are added.    (03)

Chris Menzel commented on that point very clearly:    (04)

  1. Adding more axioms makes it possible to prove more statements.    (05)

  2. But those additions don't block any previous implications.    (06)

Therefore, the users can rest assured that all their previous
assumptions will remain correct.  However, if the users had
added new axioms of their own, it's possible that they might
contradict some of the new implications added by someone else.    (07)

Those principles are true for *every* method of definition,
formal or informal, mathematical or nonmathematical.    (08)

The solution to these issues is very simple:    (09)

  1. Adopt a hierarchy of theories in which the theories *never* change.    (010)

  2. Each modification of a theory by addition creates a new theory
     that is more specialized than the original.    (011)

  3, Each modification by deletion creates a new theory that is more
     general than the original.    (012)

  4. The URIs that point to the theories are always guaranteed to
     point to a version that *never* changes.  Each modified version
     must be a different theory in the hierarchy with its own URI.    (013)

This approach ensures that users can always rely on a given URI
to point to theory that never changes.    (014)

PC> That's why I think an FO project should strive to make the FO
 > (not the domain ontologies)  as complete as possible at the earliest
 > possible point, so that changes, if they are needed, will be rare.    (015)

I'll use the term POFO for Pat's Own Foundational Ontology.  I would
suggest that you store POFO in the hierarchy so that other people
could find it, refer to it, and show how their preferred ontologies
refer to it.    (016)

But if you ever decide to make any changes to POFO, you would have
to use a different URI for the new version of POFO to avoid conflicts
with anyone who might still be using POFO 1.0.    (017)

I don't see any reason for treating POFO as something special. But
if you what to give it a more honorable status with extra ribbons,
I really don't care.  What really matters is whether users find it
more useful for their applications.  The reviews by actual users
are the most important basis for evaluations and recommendations.    (018)

John    (019)

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