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Re: [ontolog-forum] Terminologies and Ontologies

To: "'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Rich Cooper" <rich@xxxxxxxxxxxxxxxxxxxxxx>
Date: Wed, 4 May 2011 13:39:00 -0700
Message-id: <20110504203912.90BC8138CD2@xxxxxxxxxxxxxxxxx>

Hi John and Gary,


Comments below:



Rich Cooper


Rich AT EnglishLogicKernel DOT com

9 4 9 \ 5 2 5 - 5 7 1 2


John F. Sowa wrote:


Rich and Gary,


Rich's note on the new thread of Quality is related to Gary's

comment about quality in this thread.  So I'll discuss them

both in this thread.


No, there is a small but significant difference - Gary is concerned with philosophical quality of the representation and terminology, while I am concerned with the functional quality of the implementation of some representation.  


The number of instances is a QUANTITATIVE measure of the implementation that can be calculated, fed back to the ontologizer, and used to tune for higher quality over iterative development of an ontological configuration.  But the number of relations, and the total number of columns as distributed among these relations, also measure the complexity of the relational model, which IMHO id another aspect of quality, if _X is correct.  



> I found this quote on a SEMWEB list:


> “(_X) tells me that empirical evidence suggests that using a

> larger number of relationships correlates to poorer ontologies.”


> Note that _X reportedly used the descriptive word “relationship”,

> not the usual suspect “relation”, so the total number of

> tuples/rows/records in each relation that involves the ontology,

> summed over all such relations, would seem to capture the intuitive

> meaning of that phrase.


The word 'relationship' usually refers to instances rather than types.

For example, a person with a thousand Facebook "friends" has a thousand

relationships of the same type.


I suspect that _X was counting instances rather than types.  Perhaps

_X meant that a better ontology might choose relation types that

could represent the same information with fewer instances.


For example, the verb 'buy' could be defined by two instances of 'give':


    X buys Y from Z for W amount of money:


    X gives W to Z in order to cause Z to give W to X.


If your ontology does not have the concept type Buy, it would have

more instances of the simpler relations.  Perhaps that is _X's

measure of quality.  But you might ask _X.


_X has his own problems right now, so I will offer my own view.  The number of signatures which a verb can take on in well formed sentences is limited to quite a small number, a la the “verb alternations” work (what was her name?).  It’s the huge range of designations for subject, object, auxiliary, adverb, etc that makes sentences so complex.  Therefore the verb signature class, with its various type subclasses, and various component parts, should be deduced with more easily than a fully parsed sentence if one jettisons aspects of grammar in the signatures, and simply implements the expected grammatical effect in the interpreter, where it is most flexibly evaluated - at interpretation time.  


In a Q&A system, often only a fragment of a sentence in the database may be needed and relevant to an answer for a given question.  A signature case base for most English verbs, with their alternations as subclasses of each signature class, would therefore seem to be the most effective way to relate stored sentence data to the concepts detected in questions.  


So for that example, _X’s suggested “relationship” quality metric would combine the total number of relations, plus the total number of instances in each relation, plus the total number of columns used in the set of all relations.  Of course, it might be better to treat those subordinate measures orthogonally and multiply by a weighting vector that reflects the conformity of each with principles of compression, speed or other performance measure.  





> John’s example was the cutting up of some water domain into various

> categories (rivers, steams etc.) that often come to have a term

> associated with it. We might have an application dealing with floods

> in which these distinctions are important. To start on a quality

> ontology for such an application it should be able to make meaningful

> statements about what exists in its focused domain.


I agree that if a term is significant for a particular domain a good

ontology should provide some way to express it.  Sometimes, the formal

definitions have a very direct mapping to the informal terms, but

sometimes a different choice of formal relations might be more useful.


For the example about floods, you might represent the basic idea

of water flowing in a channel at a certain rate (say cubic meters

per second).  The common terms, such as creek, stream, and river

might be less useful, since a flooded creek might have a greater

flow than a river during a dry spell.


You might also choose to represent the maximum desired channel

depth and define a flood by the distance above that depth.



> The hydrological concepts are more basic and underlie the real world

> phenomena at the river-stream level. For many applications they will

> therefore organized things.


That depends on your application.  If you happen to be a landscape

designer, you might consider the common terms as useful ways to

characterize the visual features in your design.



> ... for IT applications we need to formalize these axioms in a language

> that on the one hand faithfully reflects this conceptualization and

> on the other can be processed by applications.


Yes, but I would emphasize the word 'application'.  The quality of

an ontology depends critically on the way its used in an application.

Even for the same basic phenomena, different ontologies might be better

suited to one purpose or another.






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