Re: Multi-layered Knowledge Representations for Healthcare (was RE: An argument for bridging information models and ontologies at the syntactic level)

Hi Samson,

We are getting closer.

1) In the reference you site..."A class is the descriptor for a set"...

2) Earlier, you stated that "semantics of a class as denoting a set of 
instances."

I believe these two statements represent the "apples" and "oranges" you 
referenced:

Statement 1) is the traditional "a class describes the attributes and 
associations for a concept that are common to a set of instances."
Statement 2) is better described by your population example.

I wasn't objecting to 1) . I was objecting to your seeming to confusie 
the 2) with 1).

However, if you claim that "denote" means the same thing as "describe," 
then I would agree with you instead of objecting to your assertion.

To be a little clearer....The definitions in a set of dictionaries all 
"describe" the meaning of the word "farmer." However, the word "farmer" 
in a dictionary does not "denote" the set of instances of farmers in the 
world. Same with a UML class titled "farmer."

Dan



Samson Tu wrote:

> Dan,
>
> We are talking apples and oranges.
>
> I am talking about the semantics of "class", of which the Observation 
> class is an example. [1], for example, says, "A class is the 
> descriptor for a set of objects with similar structure, behavior, and 
> relationships." (p. 50)
>
> You are talking about aggregations, like an instance of Population is 
> an aggregation of Person instances. The Population class still denotes 
> a set of instances, each of which is an aggregation of Person 
> instances  (e.g., the population of subjects enrolled in trial X).
>
> The idea of a class as denoting a set of individuals is common to UML, 
> frame representation, and OWL. I would like to view, in any of these 
> formalisms, the Observation class as denoting a set of individual 
> observations, and the WhiteBloodCellCountObservation class as denoting 
> a subset of the observations whose code is the LOINC code for white 
> blood cell count.
>
> Samson
>
> [1] Rumbaugh, Jacobson, & Booch, The Unified Modeling Language 
> Reference Manual, 2nd edition.
>
> -- 
> Samson Tu                                                     email: 
> swt@stanford.edu <mailto:swt@stanford.edu>
> Senior Research Scientist                               web: 
> www.stanford.edu/~swt/ <http://www.stanford.edu/%7Eswt/>
> Center for Biomedical Informatics Research  phone: 1-650-725-3391
> Stanford University                                          fax: 
> 1-650-725-7944
>
>
>
>
>
> On Jul 23, 2008, at 8:02 PM, Dan Russler wrote:
>
>> Hi Samson,
>>
>> Sorry for my older-style jargon...
>>
>> Here is the Wikipedia entry on collection/aggregation. We often 
>> called these classes "collectors" in jargon:
>>
>>
>>