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Re: comment: http://www.w3.org/TR/swbp-n-aryRelations/

From: Natasha Noy <noy@SMI.Stanford.EDU>
Date: Mon, 16 Aug 2004 11:40:49 -0700
Message-Id: <CB5B5F4E-EFB3-11D8-929A-000A958B5C28@smi.stanford.edu>
Cc: public-swbp-wg@w3.org
To: Samson Tu <tu@SMI.Stanford.EDU>


> However, there is a possible semantic distinction between the two that 
> should be modeled explicitly. "Christine has breast tumor" uniquely 
> determines "high probablity." If you think of 
> diagnostic-relation/person/disease/probability as a relation, then the 
> first 3 forms a key.

All the more reason to replace this example. Indeed -- and this has 
come up before -- there is a question of what we are modeling here. 
Does Christine have the tumor or does she just have the high (or low) 
probability of having it (that is, we are not saying anything about her 
actually having this tumor). You can validly say either one of those 
things (and it was the latter that we had in mind for the example), 
but, perhaps, to avoid confusion we should just change the example?

> A use case "At 2004/07/31 10:00, Christine's temperature is 39 
> degrees" illustrates the the distinction better than the "Steve" use 
> case. In the temperature/person/value/time-stamp relation, 
> temperature/person/value triplet does not determine the time stamp. In 
> that sense, the "value/time-stamp" pair is the real "value" of the 
> binary temperature relation.

You nailed the issue here (better than we have!) The idea of two 
different use cases was that in one we wanted to have some additional 
information that is ancillary to the relation and in the other we want 
to have all the components to form a "key". Something like severity of 
a particular symptom can be a better example for the former. I would 
like to avoid getting into timestamps though as this another one of 
those issues that people have strong opinions about and will only cloud 
the problem we are discussing in this note.

Received on Monday, 16 August 2004 18:40:49 UTC

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