[206]                               home                           [209]

 

Friday, November 18, 2005

 

 The BCNGroup Beadgames

National Project à 

Challenge Problem  à

 Center of Excellence Proposal à

 

 

 

 

Discussion at ONTAC forum

 

 

Communication from John Sowa and Rick

 

 

 

 

 

Rick

 

Regarding the hub approach:

In our first meeting John Sowa suggested that we tried this before and we better have something new and different. The technical and philosophical principles of the world wide web answer John's question and the issue at hand is how ontology and taxonomy co-ordination informs ontology and taxonomy design, not how design restricts co-ordination.

The more interesting of these principles include tolerance, decentralization, test of independent invention, principle of least power, free extension, language mixing, and partial understanding.

See

http://www.w3.org/DesignIssues/Principles.html  and

http://www.w3.org/DesignIssues/Evolution.html

Where these principles apply, information flows through channels based on observable regularities. A channel provides an infomorphism across classifications at its source and destination based on an interpretation that meets conditions that can preserve structure or semantics. The expressiveness of a language restricts the logic used in classifications.  

Our team at GSA is currently working through a use case based on this approach using MDA and Semantic Web technologies.

Regarding FEA-RMO:

TopQuadrant's report calls out a design pattern called an Axiom Bridge which links the PRM and the BRM. So where TQ has already shown how to "connect" two FEA-RMO ontologies, what's different about other connections? Other options also include Marco Schorlemmer's IF-Maps methodology referenced here

http://www.aktors.org/technologies/ifmap/

So, I think it's in the context of information flow that will give us the new and different we need here ...

 

 

John Sowa: 

 

That's a very important point:

 

When two people (or programs) interoperate successfully, the primary requirement is *not* that they have identical worldviews on every detail.  The major constraint is that they agree on just that subset of categories that are relevant to the information flow between them.

 

Mathew West made an important point, which I modified by changing the word "unfortunately" to "inevitably", changing "several" to "untold numbers", and adding the phrase "for the purpose at hand":

 

MW as modified by John Sowa

 

[Inevitably], even with one universe  

it is theoretically possible to come up with an infinite  

number of ontologies - almost certainly none of them truly

correct, but possibly [untold numbers] of them being  

accurate enough to be useful [for the purpose at hand].

 

The professor of industrial engineering George Box made a related point in a pithy and widely quoted observation:

 

    All models are wrong; some models are useful.

 

A formal ontology is an axiomatization of a model of some domain, which may be as large as the entire universe, but more likely is a much smaller model of some domain of interacting applications.  Furthermore, the information that flows among any set of people (or programs) is usually much smaller than the union of what all of them know.

 

Matthew also added the following point:

 

MW> Merging ontologies will only be possible where the  

same choices have been made for these (and perhaps other)  

things. Between ontologies that have made different  

choices, the ontologies can be expected to differ in  

their account of the same real world phenomena in a  

way that cannot be simply merged.

 

That may be true, but we should ask the next question: If we want Program A to interoperate with Program B, why should we merge every aspect of the ontology that was used by the developers of Program A with every aspect of the ontology used by the developers of Program B?

 

One term I like is "task-oriented interoperability":  if you try to merge two ontologies, you have to look at the *union* of all the categories in both.  But if you want to enable two programs to interoperate, you only need to look at the subsets that are relevant to the task.

 

Merging two small ontologies is much, much easier.  And more importantly, if you are only looking at a specific task, it is very likely that the subsets appropriate to the task will have similar perspectives.

 

Recommendation:  Shift attention from the unsolvable problem of building, merging, and coordinating global world views to the task of developing an open-ended collection of modules that can be selected, assembled, and tailored for particular tasks or collections of tasks.

 

John Sowa