Re: domain questionnaire

JRStern wrote:
> On 22 Feb 2001 09:18:19 GMT, hidders_at_REMOVE.THIS.win.tue.nl (Jan
> Hidders) wrote:
> >Actually Codd has done that in the "second version" of the relational
> >model: RM/T. Date discusses it in his latest book. See:
> > http://www.aw.com/product/0,2627,0201547325,00.html
>
> Hmm, Amazon has just the main book at $72, wonder how a mere civilian
> orders the package offered here. Maybe the local university
> bookstore? Thanks for the pointer, I think I want the main book
> anyway.

Actually I just saw an article by Codd on RM/T on line:

  http://www.acm.org/pubs/citations/journals/tods/1979-4-4/p397-codd/

It begins with an introduction of the standard relational model, but after a couple of pages he starts explaining RM/T. Note that it is a pdf file and quite a big download.

> >But for "higher level" data models such as ORM there are also good
> >formal descriptions of their semantics plus a good philosophy
> >(inherited from NIAM) about why and how it models reality.
>
> Not sure I follow -- also in Date's book?

No, ORM can be roughly described as a dialect of entity-relationship models, but with a very good formal underpinning and an elaborate and well-defined set of notations for constraints.

> >> Which is to say, that the issue of whether a database should
> >> reflect an external ontology or not (and if so, how, and by what
> >> theory), I think maps directly to this issue of how object
> >> identity must be handled, ...
> >
> >I agree. I think it is reasonable to assume that if the database
> >reflects an external ontology then every object should be somehow
> >identifiable. (If you cannot identify the things you are talking about,
> >then how do you know what you are talking about?)
>
> Have you ever read the philosophical works of Ruth Garrett Millikan?

No, but the name sounds very familiar. Is her work similar to that of Quine?

> I'm not sure she ever heard of computers or database, she's about
> philosophy of language and/or philosophy of mind, or thereabouts. I'm
> ploughing through this book, and in several years of looking for
> relevant theory, this is by far the best! She makes quite an issue of
> identifying versus classifying, ... I'm not certain I can summarize it
> here or apply it to database theory, not yet, but soon!

Ok. I'll wait. :-)

> On Clear and Confused Ideas: An Essay about Substance Concepts
> Ruth Garrett Garrett Millikan
>
> http://shop.barnesandnoble.com/booksearch/isbnInquiry.asp?isbn=052162553X

Thanks for the pointer, but I won't make promises because I have this big stack of books that I still have to read first.

> >What is not so obvious is that this should neccessarily be done by
> >means of the attributes of the object. I think it is quite
> >acceptable to have objects that are identified by a combination of
> >some attributes and relationships.
>
> I'm not sure even relationship is a necessary attribute. Identity
> does not have to be a relational thing at all, the relations can come
> later, between entities, that have an identity property orthogonal to
> the values of attributes and tuples.

Well, I wonder if that is really meaningful. How can I tell if objects are different if I do not know any property or relationship that it has with other objects?

-- 
  Jan Hidders